Neurotechnologies Plenary starts at 2:30 PM PT
Join live event
>
Conference 11665

Fiber Lasers XVIII: Technology and Systems

Digital Forum: On-demand now
All sponsors
Show conference sponsors + Hide conference sponsors
View Session ∨
  • Welcome and Introduction
  • LASE Plenary and Hot Topics I
  • LASE Plenary and Hot Topics II
  • Conference Networking Event
  • Best Student Presentation Awards Ceremony
  • 1: High Power Fiber Sources
  • 2: Mid-IR Fiber Lasers
  • 3: Nonlinear Effects in Fiber Lasers
  • 4: Er-Yb and Raman Fiber Sources
  • 5: Transverse Modal Instabilities in Fiber Amplifiers I
  • 6: Transverse Modal Instabilities in Fiber Amplifiers II
  • 7: Ultrafast Fiber Lasers
  • 8: Pulsed Fiber Lasers and Laser Dynamics
  • 9: Coherent Beam Combination Fiber Lasers
  • 10: Novel Fiber Sources
  • 11: Nover Fibers for Laser Applications
  • 12: Special Session I: TMI in Photonics
  • 13: Special Session II: TMI in Industry
  • Poster Session
  • Front Matter: Volume 11665
2021-03-08T02:04:24-08:00
LIVE NOW:
-
UPCOMING LIVE EVENTS:
Welcome and Introduction
11665-800
Author(s): Michalis N. Zervas, Optoelectronics Research Ctr. (United Kingdom)
Digital Forum: On-demand
Show Abstract + Hide Abstract
Welcome and Introduction to SPIE Photonics West LASE conference 11665: Fiber Lasers XVIII: Technology and Systems
LASE Plenary and Hot Topics I
11664-501
Passion extreme light (Plenary Presentation)
Author(s): Gérard A. Mourou, École Polytechnique (France)
8 March 2021 • 6:05 AM - 7:00 AM PST
This event occurred in the past
Show Abstract + Hide Abstract
Extreme-light laser is a universal source providing a vast range of high energy radiations and particles along with the highest field, highest pressure, temperature and acceleration. It offers the possibility to shed light on some of the remaining unanswered questions in fundamental physics like the genesis of cosmic rays with energies in excess of 1020 eV or the loss of information in black-holes. Using wake-field acceleration some of these fundamental questions could be studied in the laboratory. In addition extreme-light makes possible the study of the structure of vacuum and particle production in "empty" space which is one of the field’s ultimate goal, reaching into the fundamental QED and possibly QCD regimes. Looking beyond today’s intensity horizon, we will introduce a new concept that could make possible the generation of attosecond-zeptosecond high energy coherent pulse, de facto in x-ray domain, opening at the Schwinger level, the zettawatt, and PeV regime; the next chapter of laser-matter interaction.
11676-502
Author(s): Ursula Keller, ETH Zurich (Switzerland)
8 March 2021 • 7:00 AM - 7:23 AM PST
This event occurred in the past
Show Abstract + Hide Abstract
A fully stabilized optical frequency comb provides equally spaced frequencies for a precise ruler in optical frequency metrology. This talk will review recent progress in dual-comb generation from diode pumped solid-state and vertical emitting semiconductor lasers. In dual-comb modelocked operation, the initially unpolarized beam is split with an intracavity birefringent crystal. A mode-locked integrated external-cavity surface-emitting laser (MIXSEL) integrates both the gain and the saturable absorber layer within the same semiconductor wafer which simplifies the laser geometry to a linear straight cavity with excellent noise performance. A dual-comb gigahertz optically pumped MIXSEL has been used for molecular spectroscopy and lidar applications without the need of any additional stabilization. More recently a dual-comb diode-pumped Yb:CaF2 laser has been demonstrated at 140 MHz. For lidar applications we compare both lasers demonstrating micron precision over a potential ambiguity range of multi-kilometers and multi-kilohertz update rates.
11664-503
Author(s): Marwan Abdou Ahmed, Univ. Stuttgart (Germany)
8 March 2021 • 7:25 AM - 7:45 AM PST
This event occurred in the past
Show Abstract + Hide Abstract
LASE Hot Topics presentation on Development of High-Power Ultrafast Lasers: Status and Perspectives
11674-504
3D nanoprinting (Plenary Presentation)
Author(s): Maria Farsari, Foundation for Research and Technology-Hellas (Greece)
8 March 2021 • 7:45 AM - 8:05 AM PST
This event occurred in the past
Show Abstract + Hide Abstract
LASE Hot Topics presentation on 3D nanoprinting
LASE Plenary and Hot Topics II
11672-505
Author(s): Susumu Noda, Kyoto Univ. (Japan)
8 March 2021 • 12:05 PM - 12:50 PM PST
This event occurred in the past
Show Abstract + Hide Abstract
Photonic crystal surface-emitting lasers (PCSELs) are an unprecedented type of semiconductor laser that can achieve single longitudinal- and lateral-mode oscillation even over areas of millimeters in diameter. Their brightness, defined as power per unit area per unit solid angle, is expected to be increased up to the range of 1~10GWcm-2sr-1, which is comparable to those of gas lasers and fiber lasers. Also, PCSELs have additional functions, including the generation of beams with various patterns and polarizations, and they can even achieve electric two-dimensional beam scanning. Material systems for PCSELs are currently being expanded to not only InGaAs/GaAs (900-1000nm), but also InGaAsP/InP (1.3-1.55um) and even InGaN/GaN (400-530nm). LiDAR is discussed as one example of the applications of PCSELs. PCSELs will become a key light source in the forthcoming ultra-smart Society 5.0, which includes smart mobility and smart processing.
11677-506
Author(s): Manyalibo J. Matthews, Lawrence Livermore National Lab. (United States)
8 March 2021 • 12:50 PM - 1:10 PM PST
This event occurred in the past
Show Abstract + Hide Abstract
LASE Hot Topics presentation on Controlling 3D printed metal properties using tailored laser beams
11664-507
Author(s): Satoshi Kako, NTT Research, Inc. (United States)
8 March 2021 • 1:10 PM - 1:30 PM PST
This event occurred in the past
Show Abstract + Hide Abstract
Combinatorial optimization problems are ubiquitous in modern science, engineering, and medicine. Various machines using quantum or classical systems have been proposed to tackle those time-consuming problems in the past several years. A coherent Ising machine based on a nonlinear oscillators network was proposed in 2011. Its potential has been examined theoretically and experimentally since the first proof-of-concept experiment appeared in 2014. Here we review some of the important findings of the coherent Ising machines together with recent progress.
Session LIVE: Conference Networking Event
Show Abstract + Hide Abstract
Hosted by Conference Co-Chair César Jáuregui-Misas, Friedrich-Schiller-Univ. Jena (Germany) Light & Magic – One of the most important aspect of conferences is the human interaction aspect: getting to meet colleagues from all over the world and catch up on the latest news about their lives and work. Unfortunately, this difficult situation we are all going through has robbed us of that, and we are all left craving for human contact. This informal session is intended to be a gathering point were we can bring a little bit of human interaction (and magic) back into our lives. Join us to discuss about light, life and everything else... and maybe to experience some magical moments. So, do not forget to bring a Poker deck of cards with you. Join this open session with the conference chairs and speakers, pose your questions or follow up on questions you asked earlier in Slack after viewing the presentations. Become involved, meet new people with similar interests, and join us for this unique opportunity for some interesting networking and discussion. This session is not recorded.
Session LIVE: Best Student Presentation Awards Ceremony
11665-701
11 March 2021 • 2:00 PM - 2:30 PM PST
This event occurred in the past
Show Abstract + Hide Abstract
This session is not recorded. There will be no on-demand recording of this event. Times for this live event are Pacific Standard Time (UTC-8:00 hours). Join us for a live announcement of the best student presentation winners, with generous cash prizes sponsored by NKT Photonics and Active Fiber Lasers GmbH.
Session 1: High Power Fiber Sources
11665-1
Author(s): Nikolai Platonov, Roman Yagodkin, Joel De La Cruz, Valentin Gapontsev, IPG Photonics Corp. (United States)
Digital Forum: On-demand
Show Abstract + Hide Abstract
We report 3kW test data of Single-Mode (SM) Ytterbium fiber amplifier with diffraction-limited divergence for narrow linewidth seed sources in modular package with all-fiber format. Measured M2 values of output beam in full power range are ≤ 1.1. The Ytterbium fiber amplifier has ≥ 40% wall-plug efficiency and 15nm spectral bandwidth in 1055-1070nm wavelength range. The amplifier operates up to 3kW at linewidth of 60GHz and 30GHz with linear polarized and depolarized seed sources respectively. The amplifier data and non-linear SBS, SRS and MI effects are discussed for different input linewidth and test conditions.
11665-2
Author(s): Yi An, Huan Yang, Xiao Chen, Hu Xiao, Liangjin Huang, Pengfei Ma, Xiaoming Xi, Xiaolin Wang, Pu Zhou, Zhiyong Pan, Zongfu Jiang, National Univ. of Defense Technology (China)
Digital Forum: On-demand
Show Abstract + Hide Abstract
In this study, we design and fabricate a novel type of active fiber——double-tapered double-clad fiber (DT-DCF). Based on this self-developed DT-DCF, we have constructed an all-fiberized fiber amplifier that is operating under a continuous-wave (CW) regime at 1080 nm wavelength. The maximum output power of the system reaches 4 kW, which, to the best of our knowledge, is the highest output power of tapered fiber-based laser systems. The amplifier exhibits near-single-mode beam quality (M2=1.33) at the highest output power with a slope efficiency of 83%. Our result successfully verifies the potential of power scalability of DT-DCF, and the performance of our system can be further enhanced by fiber design optimization.
11665-3
Author(s): Roopa Prakash, B. S. Vikram, V. R. Supradeepa, Indian Institute of Science, Bengaluru (India)
Digital Forum: On-demand
Show Abstract + Hide Abstract
Power scaling of continuous-wave, narrow-linewidth fiber lasers are limited by the onset of stimulated Brillouin scattering (SBS) which manifests at threshold as potentially damaging, high peak power, backward propagating pulses. We propose a simple and effective technique of SBS suppression, by using a novel dual sine and noise modulation scheme for line broadening. We experimentally compare this scheme to the pure noise broadened case at similar linewidths and demonstrate over 2.36x enhancement in SBS limited output power. Using this modulation scheme, we demonstrate >1kW output power at ~10.4GHz linewidth in a polarization maintaining laser built with off the shelf components.
11665-4
Author(s): Nezih Belhadj, Aouatif Qasmi, Jean-Noel Maran, CorActive High-Tech Inc. (Canada); Congwen Zha, Zihao Zhang, Shuzhen Ma, Han's Laser Technology Industry Group Co., Ltd. (China)
Digital Forum: On-demand
Show Abstract + Hide Abstract
We are reporting a monolithic all-fiber multimode laser reaching a stable 4 kW output power allowing enhanced Stimulated Raman Scattering rejection, no Transverse Mode Instability either photodarkening. This is made possible by developing a highly multimode phosphosilicate double-cladding Yb-doped fiber having 25 micron and 400 micron as core and inner cladding diameters and 0.16 as core numerical aperture. The achievement of a high reflectivity fiber Bragg grating written on highly multimode passive fiber made the multimode laser cavity feasible. This result demonstrates that multimode laser oscillation is an efficient method to mitigate non-linear effects.
11665-5
Author(s): Vincent Roy, Paul Grenier, Louis Desbiens, Sebastien Deshaies, Marc Deladurantaye, Patrick Paradis, Mathieu Boivin, Bruno Labranche, Antoine Proulx, Yves Taillon, INO (Canada)
Digital Forum: On-demand
Show Abstract + Hide Abstract
A short-pulse Yb-doped fiber laser based on a master oscillator and power amplifier scheme is reported to yield an average power exceeding 500 W and pulse energy over 1 mJ. The final amplifier stage features a polarization-maintaining, large mode area tapered fiber with core/cladding diameters of 35/250 µm and 56/400 µm at each end of the flared section. The latter yields excellent optical conversion efficiency, near diffraction-limited output, narrow spectral linewidth and high polarization extinction ratio. Besides, no indication for transverse mode instability could be observed below the stimulated Raman scattering threshold, as beam quality M2 was measured < 1.3 and no fluctuations were further detected from photodiode time traces of near-field laser beam samples.
Session 2: Mid-IR Fiber Lasers
11665-7
Author(s): Brian M. Anderson, Air Force Research Lab. (United States); Joel Soloman, University of North Carolina (United States); Angel Flores, Air Force Research Lab. (United States)
Digital Forum: On-demand
Show Abstract + Hide Abstract
A 1.1 kW CW fiber amplifier emitting at 1.95µm and phase modulated at 5 GHz, with 51% optical conversion efficiency and near diffraction limited beam quality (M2<1.1) is demonstrated. The fiber amplifier consists of 9m of active 20/400um thulium doped fiber, and 2m of passive delivery fiber. Several limiting nonlinearities critical to maintaining coherence were analyzed, including stimulated Brillouin Scattering and modulation instability. To our knowledge, this is the first kw-class thulium doped fiber amplifier operating with narrow linewidth.
11665-8
Author(s): Paul Repgen, Benedikt Schuhbauer, Moritz Hinkelmann, Dieter Wandt, Andreas Wienke, Laser Zentrum Hannover e.V. (Germany); Uwe Morgner, Leibniz Univ. Hannover (Germany); Jörg Neumann, Dietmar Kracht, Laser Zentrum Hannover e.V. (Germany)
Digital Forum: On-demand
Show Abstract + Hide Abstract
The principle of a Mamyshev oscillator depends on alternating spectral filtering between sections of spectral broadening by self-phase modulation. In the 2 µm wavelength range, this concept faces the difficulty that standard fibers are anomalous dispersive which limits the possible pulse energy to the pJ-regime without proper dispersion management. We applied ultra-high numerical aperture fibers with normal dispersion in order to achieve up-chirped pulses in an anomalous dispersive Thulium-doped gain fiber. With that design, we achieved mode-locked pulses with energies of 6.4 nJ and a compressed autocorrelation duration of 195 fs at a repetition rate of 16 MHz.
11665-9
Author(s): Qian Zhang, Yubin Hou, Weihua Song, Xi Wang, Zhigang Peng, Beijing Univ. of Technology (China); Xu Chen, Carl Blair, Li Ju, Chunnong Zhao, The Univ. of Western Australia (Australia); Pu Wang, Beijing Univ. of Technology (China)
Digital Forum: On-demand
Show Abstract + Hide Abstract
We demonstrated an ultra-low noise polarization-maintaining (PM) single frequency fiber laser (SFFL) at 2 µm. By suppressing the pump relative intensity noise (RIN) using a feedback loop control, the RIN and frequency noise of the SFFL are simultaneously reduced, and the reduction is about 3 - 15 dB and 3 - 8.4 dB, respectively. After two stage Tm3+-doped PM fiber amplifier, the output power reached about 5 W. Meanwhile, the frequency noise almost has no increases, which is still below 100 Hz/√Hz after 13 Hz. And the frequency-tunable range is approximately 2 GHz with frequency response of 46 MHz/V.
11665-10
Author(s): Lu Zhang, Junxiang Zhang, Quan Sheng, Shuai Sun, Chaodu Shi, Tianjin Univ. (China); Shijie Fu, !Wyant College of Optical Sciences (United States); Xiaolei Bai, Inner Mongolia Univ. (China); Wei Shi, Jianquan Yao, Tianjin Univ. (China)
Digital Forum: On-demand
Show Abstract + Hide Abstract
We demonstrated an efficient, 1720-nm Tm-doped all-fiber laser based on ring-cavity configuration. A high-reflectivity narrow-linewidth fiber Bragg grating, centered at 1720 nm was used to suppress amplified spontaneous emission at 1.8–1.9-μm and select 1720-nm modes. Laser output at different output couplings were investigated by using homemade output couplers based on fused taper fiber. When the output coupling was 78%, 2.36-W 1720-nm laser output was obtained under 5.5-W absorbed pump power, while the laser threshold was 1.07-W and the slope efficiency reached 50%.
11665-11
Author(s): Robert E. Tench, Jean-Marc Delavaux, Cybel LLC (United States); Clement Romano, Fraunhofer-Institut für Optronik, Systemtechnik und Bildauswertung IOSB (Germany)
Digital Forum: On-demand
Show Abstract + Hide Abstract
Ho-doped fiber amplifiers (HDFAs) operating in the 2000 nm—2100 nm band are key enablers for infrared LIDAR, atmospheric sensing, trace gas detection, and DWDM transmission system applications. All of the in-band pumped HDFAs demonstrated to date have employed an optical pumping wavelength near 1940 nm. In this paper we present comprehensive studies of simulated HDFA performance as a function of pump wavelength with particular attention to the region of 1720—2000 nm. We demonstrate with simulations and experiment that a new pump wavelength of 1860 nm yields significantly improved results for both output power (+ 3-6 dB) and gain (+ 5-11 dB) for in-band pumped HDFAs.
Session 3: Nonlinear Effects in Fiber Lasers
11665-12
Author(s): Brian M. Anderson, Air Force Research Lab. (United States); Kenneth MacDonald, Aberaham Taliaferro, Leidos (United States); Angel Flores, Air Force Research Lab. (United States)
Digital Forum: On-demand
Show Abstract + Hide Abstract
Stimulated Brillouin scattering (SBS) is typically the lowest order nonlinearity encountered in ytterbium doped fiber amplifiers (YDFA), and the simplest means of suppressing it is though linewidth broadening from phase modulation. However, to maintain compatibility with beam combining techniques critical to scaling to high output powers, narrow linewidths are needed, and bandwidth efficient means of suppressing SBS are key to scaling to high powers. Here, the scalability of novel phase modulation techniques in combination with laser gain competition are explored. Ultimately, LGC is shown to improve the TMI threshold by 15%, and reduce the linewidth by a factor of 2.1. A 1.8 kW fiber amplifier with 7 Ghz linewidth is demonstrated.
11665-13
Author(s): Sergey Tsvetkov, Maxim Khudyakov, A. M. Prokhorov General Physics Institute (Russian Federation); Alexey Lobanov, Denis Lipatov, G. G. Devyatykh Institute of Chemistry of High-Purity Substances (Russian Federation); Mikhail Bubnov, A. M. Prokhorov General Physics Institute (Russian Federation); Valery Temyanko, !Wyant College of Optical Sciences (United States); Mikhail E. Likhachev, A. M. Prokhorov General Physics Institute (Russian Federation)
Digital Forum: On-demand
Show Abstract + Hide Abstract
A strong SBS gain suppression can be achieved in ordinary passive single-mode optical fibers due the proper multimode acoustic refractive index profile (ARIP) design. Due to the co-doping technique the ARIP can be fabricated strongly multimoded to obtain the widest potential SBS gain spectrum range, whereas the ARIP shape optimization provides the maximum possible number of the acoustic modes with equal acousto-optic interaction coefficients. This approach does not affect the optical properties of the fiber and can be realized for different fiber types and doping compounds.
11665-14
Author(s): Ning Wang, CREOL, The College of Optics and Photonics, Univ. of Central Florida (United States), Department of Network and IT Technology, China Mobile Research Institute (China); Juan Carlos Alvarado Zacarias, CREOL, University of Central Florida (United States); Yinping Liu, Guangyao Yang, Shanghai Jiao Tong University (China); He Wen, Jose Enrique Antonio-Lopez, CREOL (United States); Pierre Sillard, Adrian Amezcua-Correa, Prysmian Group (France); Zuyuan He, Shanghai Jiao Tong University (China); Rodrigo Amezcua-Correa, CREOL (United States); Guifang Li, CREOL, The College of Optics and Photonics, Univ. of Central Florida (United States)
Digital Forum: On-demand
Show Abstract + Hide Abstract
Fiber lasers of high-order spatial modes are advantageous in a number of applications. We experimentally demonstrate a transverse mode-selective few-mode Brillouin fiber laser using a pair of mode-selective photonic lanterns as spatial mode filters. The three LP lasing modes were generated based on both intra- and inter-modal stimulated Brillouin scattering. Their slope efficiencies, optical spectra, mode profiles, and linewidths were characterized for both cases. Based on the ring-cavity configuration, distributed temperature and strain sensing with 1-m spatial resolution is also demonstrated. The Brillouin dynamic grating was generated in the LP01 mode and high-order modes were used as probes. The feasibility of simultaneous temperature and strain sensing has also been investigated.
11665-15
Author(s): Junxiang Zhang, Quan Sheng, Lu Zhang, Shuai Sun, Chaodu Shi, Tianjin Univ. (China); Shijie Fu, !Wyant College of Optical Sciences (United States); Wei Shi, Jianquan Yao, Tianjin Univ. (China)
Digital Forum: On-demand
Show Abstract + Hide Abstract
We observed a large optical bistability in a single-frequency thulium fiber laser with ring cavity configuration. A piece of unpumped Tm-doped fiber served as nonlinear saturable absorber (SA), which also acted as a narrow-bandpass filter by forming self-induced gratings with counter-propagate lasers and enabled single-frequency laser operation at 1720 nm. Due to the large absorption cross section of thulium ions at 1720 nm, the unpumped Tm-doped fiber has large variable losses, hence resulting in strong optical bistability. With 0.75-m SA fiber, a 4.8-W wide bistable region was achieved, and the method of optical bistability control was discussed and experimentally investigated.
11665-17
Author(s): Alioune Niang, Univ. degli Studi di Brescia (Italy); Mesay A. Jima, Univ. degli Studi di Brescia (Italy), Univ. de Limoges (France); Daniele Modotto, Fabio Mangini, Univ. degli Studi di Brescia (Italy); Alessandro Tonello, XLIM, Univ. de Limoges (France); Umberto Minoni, Univ. degli Studi di Brescia (Italy); Marc Fabert, Univ. de Limoges (France); Mario Zitelli, Sapienza Univ. di Roma (Italy); Vincent Couderc, Univ. de Limoges (France); Stefan Wabnitz, Sapienza Univ. di Roma (Italy)
Digital Forum: On-demand
Show Abstract + Hide Abstract
We analyzed the nonlinear dynamics of pulsed beam self-cleaning in nonlinear tapered Ytterbium doped and Erbium-Ytterbium codoped graded-index multimode optical fibers, with uniform doping distribution in the core cross-section. By increasing the input coupled peak power (passive configuration) or gain by a pump laser diode (active configuration), the output spatial intensity distribution changed from a speckled into a high beam quality, bell-shaped pattern. In the taper, self-cleaning is obtained without accompanying self-phase modulation induced spectral broadening or frequency conversion when the input laser beam was launched into the small core side.
Session 4: Er-Yb and Raman Fiber Sources
11665-18
Author(s): Turghun Matniyaz, Clemson Univ. (United States); Fanting Kong, Clemson Univ. (United States), Coherent, Inc. (United States); Monica T. Kalichevsky-Dong, Liang Dong, Clemson Univ. (United States)
Digital Forum: On-demand
Show Abstract + Hide Abstract
There has been very little progress in the power scaling of Er/Yb fiber lasers in over a decade, reflecting the difficulties involved. Here we report a new record of 302W single-mode power from an Er/Yb fiber master oscillator power amplifier (MOPA) with a record optical efficiency of 56%, near the quantum limit. This is made possible by new fiber development from Nufern and off-resonant pumping of the Er/Yb fiber. We also show that further power scaling is no longer limited by ytterbium parasitic lasing but by fiber fuse in the Er/Yb fiber.
11665-19
Author(s): Liang Dong, Turghun Matniyaz, Monica T. Kalichevsky-Dong, Clemson Univ. (United States); Johan Nilsson, Univ. of Southampton (United Kingdom); Yoonchan Jeong, Seoul National Univ. (Korea, Republic of)
Digital Forum: On-demand
Show Abstract + Hide Abstract
Conventional models of Er/Yb co-doped fibers assume all ytterbium ions are equally involved in the energy transfer with erbium ions, governed by a singular transfer rate. This would predict output power clamping once ytterbium parasitic lasing starts, contrary to the observations that the output continued to grow albeit at a slower rate. One study explained this using elevated temperature at high powers. Our study, however, shows that elevated temperature and mode-dependent effects only play insignificant roles. A new model is developed based on the existence of isolated ytterbium ions, which can explain all the observed experimental behaviors.
11665-20
Author(s): Phillip Booker, Omar de Varona, Laser Zentrum Hannover e.V. (Germany); Michael Steinke, Peter Wessels, Laser Zentrum Hannover e.V. (Germany), Exzellenzcluster QuantumFrontiers (Germany); Jörg Neumann, Laser Zentrum Hannover e.V. (Germany); Dietmar Kracht, Laser Zentrum Hannover e.V. (Germany), Exzellenzcluster QuantumFrontiers (Germany)
Digital Forum: On-demand
Show Abstract + Hide Abstract
Single-frequency Er3+:Yb3+ co-doped fiber amplifiers are promising candidates for laser sources in the next-generation of gravitational wave detectors. In this work, we present the recent progress on a fully monolithic, 2-stage single-frequency EYDFA that utilizes polarization-maintaining fibers. We present a comprehensive study on different pre-amplifier concepts with a seed input power of 8mW and sub-MHz linewidth. We discuss the limitations and demonstrate that cladding-pumping with 940nm provides the highest gain without the onset of ASE and a maximum output power of 1.07W. Furthermore, we demonstrate SBS-free operation of the pre-amplifier. The high-power amplifier was also pumped at 940nm. The high-power amplifier provided an output power of 110W in a Gaussian-like mode, had an ASE extinction ratio of >50dB and only marginal Yb3+ ASE power levels. We show that the amplifier operated SBS-free and discuss the polarization and long-term performance.
11665-21
Author(s): Andrew T. Grimes, Anand Hariharan, Jeffrey W. Nicholson, OFS (United States)
Digital Forum: On-demand
Show Abstract + Hide Abstract
We report the results from Raman fiber lasers with CW output powers of 224 Watts at 1.48 µm and 168 Watts at 1.7 µm, both of which are to the best of our knowledge the highest output powers from cascaded Raman resonators at these wavelengths. The Raman fiber lasers use unique Raman filter fibers to prevent threshold at the next Stokes wavelength, allowing for high spectral purity in the desired Stokes band. In addition, the 1.7 µm output is pulsed to achieve 1.4 mJ in an 8.5 µs FWHM pulse.
11665-22
Author(s): Sarthak Dash, Rashmita Deheri, Vishal Choudhury, V. R. Supradeepa, Indian Institute of Science, Bengaluru (India)
Digital Forum: On-demand
Show Abstract + Hide Abstract
Random distributed feedback Raman lasers enable widely tunable high-power laser sources in the NIR wavelengths. Currently, coarse tuning is achieved by control of the Raman Stokes order through power and feedback tuning while fine tuning within a Stokes order is achieved using a pump laser which is wavelength tunable. However, this approach enhances the requirements for the pump source to be wavelength tunable increasing its complexity. Here, we demonstrate a new architecture for cascaded Raman lasers which achieves wavelength tunability with a fixed wavelength pump, A Fourier spectral shaper is utilized for enhanced control of the random distributed feedback.
Session 5: Transverse Modal Instabilities in Fiber Amplifiers I
11665-24
Author(s): Liang Dong, Clemson Univ. (United States); Fanting Kong, Coherent Inc (United States); Roger H. Stolen, Clemson Univ. (United States)
Digital Forum: On-demand
Show Abstract + Hide Abstract
It is generally understood now that the physical origin of TMI is stimulated thermal Rayleigh scattering (STRS), where modal interference causes index grating via quantum heating. The grating is perfectly phase-matched for the two-mode coupling, which can become very significant at high powers, leading to mode degradation. STRS is very similar to SBS. The grating needs to be traveling to satisfy the required phase condition and, therefore, the coupled power is frequency-shifted. Measurement of STRS spectral gain is critical for the understanding of TMI. We directly measured the STRS spectral gain in 2016, and firmly established STRS’s role in TMI.
11665-25
Author(s): Oleg Leonidovich Antipov, Maxim S. Kuznetsov, Institute of Applied Physics of the RAS (Russian Federation); Valentin Tyrtyshnyy, Dmitry Alekseev, NTO “IRE-Polus” (Russian Federation)
Digital Forum: On-demand
Show Abstract + Hide Abstract
We present an overview of theoretical analysis and experimental observation of the spatio-temporal transverse mode instability in polarization-maintaining high-gain fiber amplifiers with a high concentration of Yb3+ ions and core diameters of 8-10 μm. The nonlinear power transformation of the LP01 fundamental mode into the high-order modes is explained by a traveling refractive index grating accompanying a population grating induced by the mode interference field. The origin of the refractive index gratings is discussed. The threshold power for the transverse mode instability is found to depend on the fiber core diameter, numerical aperture, dopant concentration and the signal bandwidth. The threshold power is observed to decrease dramatically in the presence of a backward reflection of a signal from the output fiber facet.
11665-26
Author(s): Michalis N. Zervas, Optoelectronics Research Ctr. (United Kingdom)
Digital Forum: On-demand
Show Abstract + Hide Abstract
In this work we study the conditions for the onset of modal instabilities in two-mode fiber amplifiers. We show that transverse-mode instability (TMI) results as a consequence of cross-phase modulation and four-wave mixing process. The TMI threshold condition corresponds to a self-phase and cross-phase modulation induced nonlinear phase matching between LP01 and LP02 modes. The derived TMI power threshold shows a functional dependence similar to previously derived formula.
11665-27
Author(s): Cesar Jauregui-Misas, Friedrich-Schiller-Univ. Jena (Germany); Christoph Stihler, Friedrich-Schiller-Univ. Jena (Germany), Fraunhofer-Institut für Angewandte Optik und Feinmechanik IOF (Germany); Sobhy E. Kholaif, Yiming Tu, Friedrich-Schiller-Univ. Jena (Germany); Jens Limpert, Friedrich-Schiller-Univ. Jena (Germany), Helmholtz-Institut Jena (Germany), Fraunhofer-Institut für Angewandte Optik und Feinmechanik IOF (Germany)
Digital Forum: On-demand
Show Abstract + Hide Abstract
In this work we propose a new and practical passive mitigation approach exploiting polarization effects in PM fibers. PM fibers exhibit modal birefringence, i.e. the level of birefringence observed by different transverse modes is also different. Thus, when coupling light in the two main polarization axes simultaneously, two modal interference patterns with slightly different periods will be generated. In turn, this will result in periodic regions along the fiber where the overall modal interference pattern is washed out and, with it, the thermally-induced refractive index grating. Therefore, this approach will lead to the mitigation of TMI.
11665-28
Author(s): Christoph Stihler, Friedrich-Schiller-Univ. Jena (Germany), Fraunhofer-Institut für Angewandte Optik und Feinmechanik IOF (Germany); Cesar Jauregui, Sobhy E. Kholaif, Yiming Tu, Friedrich-Schiller-Univ. Jena (Germany); Jens Limpert, Friedrich-Schiller-Univ. Jena (Germany), Fraunhofer-Institut für Angewandte Optik und Feinmechanik IOF (Germany), Helmholtz-Institut Jena (Germany)
Digital Forum: On-demand
Show Abstract + Hide Abstract
A new mitigation strategy for transverse mode instability (TMI) in high-power fiber amplifiers is presented which suppresses the root cause of the effect. In this approach, the excitation of the fiber is dynamically changed (e.g. by an acousto-optic deflector), which varies the intensity profile that develops in the fiber. By applying a frequency of a few hundreds of kHz, the inversion grating will be washed out, which will result in a homogenized heat distribution. Thus, the formation of a refractive index grating, which is responsible for the TMI-induced mode coupling, can be impaired.
11665-29
Author(s): Friedrich Möller, Fraunhofer-Institut für Angewandte Optik und Feinmechanik IOF (Germany); Victor Distler, Fraunhofer-Institut für Angewandte Optik und Feinmechanik IOF (Germany), Friedrich-Schiller-Univ. Jena (Germany); Maximilian Strecker, Till Walbaum, Thomas Schreiber, Fraunhofer-Institut für Angewandte Optik und Feinmechanik IOF (Germany)
Digital Forum: On-demand
Show Abstract + Hide Abstract
We report on the observation and experimental characterization of backward transverse mode instability (TMI). Up to now, TMI has only be described in terms of forward field interaction leading to a power coupling from the forward amplified fundamental mode to the forward higher order mode. Experiments with a monolithic Ytterbium-doped fiber amplifier in 20/400 µm geometry reveal a strong temporal correlation of forward and backward propagating light once the TMI threshold is reached. Investigation on the modal content in forward and backward direction will be discussed as well as the origin of this behavior.
Session 6: Transverse Modal Instabilities in Fiber Amplifiers II
11665-30
Author(s): Simon Lønborg Christensen, Technical Univ. of Denmark (Denmark), NKT Photonics A/S (Denmark); Mette Johansen, Mattia Michieletto, Marco Triches, Martin Maack, NKT Photonics A/S (Denmark); Jesper Lægsgaard, Technical Univ. of Denmark (Denmark)
Digital Forum: On-demand
Show Abstract + Hide Abstract
In this work we investigate transverse mode instability (TMI) in the presence of pump intensity noise and a controlled perturbation of the input coupling for a rod-type fiber amplifier using spatially and temporally resolved imaging (ST). We show that inherent pump intensity noise from the power supply can define significant peaks in the resulting TMI spectrum. ST measurements in the transition region of TMI also indicates that the simple picture of TMI being seeded by the combination of a static initial fraction of LP11 and pump or signal intensity noise is not valid for our measurements. Furthermore, we present seeding of TMI by perturbing the input coupling dynamically which allows measurements of the TMI gain as a function of frequency and signal power.
11665-31
Author(s): Andy Malinowski, Christophe A. Codemard, SPI Lasers UK Ltd. (United Kingdom); Michalis N. Zervas, Optoelectronics Research Ctr. (United Kingdom)
Digital Forum: On-demand
Show Abstract + Hide Abstract
A new fast dynamic BPM model for TMI investigation is presented and used to study the evolution of the internal powers, inversion and thermal gratings and the impact of relative phase shifts on the amplifier dynamics, showing the prevalence and importance of nonlinearly-induced beat-length variations. We also show that non-monotonic “shrinkage”/ “dilation” of the local beat length occurs due to the accumulated thermally-induced nonlinear differential modal phase shifts. This is a consequence of the time-delayed thermal action and lies at the heart of the TMI effect.
11665-32
Author(s): Benjamin G. Ward, Defense Threat Reduction Agency (United States)
Digital Forum: On-demand
Show Abstract + Hide Abstract
Results of steady periodic finite element beam propagation simulations of transverse mode instability (TMI) in fiber amplifiers with pump noise and modulation are presented and discussed. These results were used to synthesize spatially and temporally resolved imaging measurements including spatial distribution of the amplitude and phase of different frequency components as a means to characterize the effects of pump modulation on TMI dynamics. Characteristics of pump modulation were found to affect the dynamics of TMI in a range of amplifier configurations and modulation cases.
11665-33
Author(s): Till Walbaum, Friedrich Möller, Victor Distler, Maximilian Strecker, Thomas Schreiber, Fraunhofer-Institut für Angewandte Optik und Feinmechanik IOF (Germany)
Digital Forum: On-demand
Show Abstract + Hide Abstract
The analysis of TMI has advanced over the last decade, with added observation parameters depending on the complexity of the experimental system. Increasing levels of information have been extracted, from camera images in the beginning over modal decomposition, time trace and frequency analysis, on towards bi directional measurements at multiple system positions and separation of spectral components. We will give an overview of the evolution of TMI analysis for different model systems and discuss the applicability and the additional insight that can be gained from advanced observation methods.
11665-34
Author(s): Sobhy E. Kholaif, Yiming Tu, Christoph Stihler, Cesar Jauregui, Jens Limpert, Friedrich-Schiller-Univ. Jena (Germany)
Digital Forum: On-demand
Show Abstract + Hide Abstract
A new approach to characterize the effect of transverse mode instability (TMI) in high-power fiber-laser systems is presented. A position-sensitive detector is employed to detect the trajectories of the center of gravity of the fluctuating beam at different average power levels. With an increasing average output power, the area covered by the trajectories increases which is used as a measure for the stability of the system. The new concept allows for a simple, fast, and detailed characterization of TMI, which accurately determines its threshold even in complex operating regimes.
Session 7: Ultrafast Fiber Lasers
11665-35
Author(s): Kevin F. Lee, IMRA America, Inc. (United States); Gengji Zhou, Herbert G. Winful, Univ. of Michigan (United States); Jie Jiang, Martin E. Fermann, IMRA America, Inc. (United States)
Digital Forum: On-demand
Show Abstract + Hide Abstract
We demonstrate the operation of fiber Bragg grating compressors in a strongly nonlinear regime via adaptive control, allowing simultaneously for linear chirp compensation, large scale bandwidth broadening and highly effective compensation of nonlinear pulse distortions in femtosecond Er fiber amplifiers. We generate record 62 fs, 110 nJ pulses with 11 W average and 1.4MW peak power in a single mode Er fiber amplifier, bringing strong-field intensities to frequency comb repetition rates. The adaptive control presented here is applicable to any nonlinear propagation problem and can be used to greatly advance existing ultrafast fiber technology.
11665-36
Author(s): Siyun Chen, Mathew Whittlesey, Yifan Cui, Univ. of Michigan (United States); Russell Wilcox, Lawrence Berkeley National Lab. (United States); Almantas Galvanauskas, Univ. of Michigan (United States)
Digital Forum: On-demand
Show Abstract + Hide Abstract
We report demonstration of a new spectrally-controllable device, based on a sequence of linear polarizers and birefringent plates, which allows to accurately and adjustably tailor its spectral filtering properties for achieving complete gain-narrowing compensation over ~30nm of signal bandwidth in an Yb-doped fiber system with the total gain reaching 150dB. The experimental demonstration was performed in a regenerative Yb-fiber amplifier system with controllable number of passes, allowing to characterize both signal spectral-narrowing, and as well as spectral compensation at varying levels of achieved total gain. This result opens a pathway towards 100fs duration multi-mJ pulses from fiber CPSA systems.
11665-37
Author(s): Mateusz Pielach, Bernard Piechal, !Institute of Physical Chemistry PAS (Poland); Jan Szczepanek, Fluence sp. z o.o (Poland); Piotr Kabacinski, !Institute of Physical Chemistry PAS (Poland), Warsaw Univ. of Technology (Poland); Yuriy Stepanenko, !Institute of Physical Chemistry PAS (Poland)
Digital Forum: On-demand
Show Abstract + Hide Abstract
In this work, we present an all-polarization-maintaining, all-large-mode-area fiber laser oscillator passively mode-locked using a nonlinear optical loop mirror. The ytterbium-doped system, working in a Raman-free regime, operates at a central wavelength of 1.03 µm. The oscillator emits 12 nJ pulses at a repetition rate of 7.56 MHz. Positively chirped pulses from an all-normal-dispersion cavity can be externally compressed to the duration of 250 fs.
11665-38
Author(s): Paul Repgen, Dieter Wandt, Andreas Wienke, Laser Zentrum Hannover e.V. (Germany); Uwe Morgner, Leibniz Univ. Hannover (Germany); Jörg Neumann, Dietmar Kracht, Laser Zentrum Hannover e.V. (Germany)
Digital Forum: On-demand
Show Abstract + Hide Abstract
Recently, Mamyshev oscillators (MO) have attained a lot of attention, due to their generation of mode-locked pulses with outstanding output parameters in terms of output energy, spectral bandwidth and pulse duration. We present a MO with output pulse energies in the range of 0.5µJ, an optical spectrum ranging from 1010nm to 1060nm and an externally compressed autocorrelation duration of less than 100fs. This MO completely consists of commercially available standard step-index fibers. In order to handle the high pulse energies, we apply a few-mode gain fiber with a core-diameter of 20µm in the second arm of the oscillator.
11665-39
Author(s): Khmaies Guesmi, Alain Mugnier, Guillaume Canat, Céline Canal, Patrick Maine, Keopsys Industries (France)
Digital Forum: On-demand
Show Abstract + Hide Abstract
We report on a simple and robust all-fiber femtosecond MOPA system based on an optimized active tapered double-clad fiber (T-DCF). The main feature of this active medium is that the thin part, acting as a pre-amplifier, allows to propagate mostly the fundamental mode LP01, while the signal experiences an extremely high gain in the thick part of the tapered fiber, where most of the pump power is absorbed. These T-DCF properties make them particularly well suited for designing high energy CPA based femtosecond amplifiers, with a high non-linear threshold (SPM, SRS) and a diffraction limited output beam. After the compressor, we obtained pulses amplified up to 40 µJ energy, 412 fs duration and 97 MW peak power at 1036 nm. To the best of our knowledge, it is the highest peak power reported in such T-DCF amplifier in the femtosecond regime.
11665-40
Author(s): Mikko Närhi, Andrei Fedotov, Kseniia Aksenova, Regina Gumenyuk, Tampere Univ. (Finland)
Digital Forum: On-demand
Show Abstract + Hide Abstract
Fiber based Mamyshev regenerators provide potentially a low cost, pulse-on-demand source with pulse durations down to the hundred femtosecond scale. Based on nonlinear broadening of gain switched diode laser pulses in fiber and consequent pulse shaping methods, these sources could provide an alternative for mode-locked systems. Here we study numerically the properties of such sources in terms of input pulse duration and power as well as various fibers. We show that an optimum operating region can be found for each input parameter combination, that is limited mainly by the onset of spontaneous Raman scattering and optical wave breaking.
Session 8: Pulsed Fiber Lasers and Laser Dynamics
11665-41
Author(s): Simon Lotz, Christin Grill, Madita Göb, Wolfgang Draxinger, Jan Philip Kolb, Robert Huber, Univ. zu Lübeck (Germany)
Digital Forum: On-demand
Show Abstract + Hide Abstract
In Fourier domain mode locked (FDML) lasers, extremely precise and stable matching of the filter tuning period and light circulation time in the cavity is essential for ultra-low noise operation. We present an actively cavity length controlled FDML laser and a robust and high precision feedback loop algorithm for maintaining ultra-low noise operation. The closed-loop system achieves a stability of ~0.18 mHz at a sweep repetition rate of ~418 kHz which corresponds to a ratio of 4×10e-10. We investigate the coherence properties during the active cavity length adjustments and observe no noise increase compared to fixed cavity length.
11665-42
Author(s): Christin Grill, Torben Blömker, Univ. zu Lübeck (Germany); Mark Schmidt, Technische Univ. München (Germany); Dominic Kastner, Univ. zu Lübeck (Germany); Tom Pfeiffer, Univ. zu Lübeck (Germany), Optores GmbH (Germany); Jan Philip Kolb, Wolfgang Draxinger, Sebastian Karpf, Univ. zu Lübeck (Germany); Christian Jirauschek, Technische Univ. München (Germany); Robert Huber, Univ. zu Lübeck (Germany)
Digital Forum: On-demand
Show Abstract + Hide Abstract
Fourier domain mode locked (FDML) laser are fast swept light sources. Measuring its coherence length is not straightforward, but important for a physical understanding of FDML lasers and its application to OCT. To characterize the “instantaneous” linewidth, we performed beat signal measurements between a CW laser and an FDML laser and detected the signals with a 63 GHz real time oscilloscope. Our measurements suggest the existence of a distinct comb like mode structure of the FDML laser and help to determine the locking strength of individual comb lines.
11665-43
Author(s): Chaodu Shi, Hao Tian, Wei Shi, Quan Sheng, Juanxiang Zhang, Shuai Sun, Jianquan Yao, Tianjin Univ. (China)
Digital Forum: On-demand
Show Abstract + Hide Abstract
A narrow-linewidth single-frequency Yb-doped nanosecond pulsed fiber laser with 27-kW peak power was demonstrated in this work. By employing the novel triangle-shape pulse with 1-ns rise time and 13-ns fall time, the spectral linewidth of 88 MHz was achieved at the maximum output power. The signal to noise ratio was about 33 dB and no obvious residual pump power within the output laser. To the best of our knowledge, it is the first time that the performance of triangle-pulse fiber amplifier was demonstrated.
11665-44
Author(s): William Renard, Clément Chan, Irisiome Solutions (France); Jérôme Lhermite, Ctr. Lasers Intenses et Applications, Univ. de Bordeaux, CEA, CNRS (France); Giorgio Santarelli, Lab. Photonique, Numérique et Nanosciences, Institut d'Optique Graduate School, Univ. de Bordeaux (France); Romain Royon, Irisiome Solutions (France)
Digital Forum: On-demand
Show Abstract + Hide Abstract
We investigate femtosecond pulse generation from a CW Laser diode by optical gating with a Mach-Zehnder electro-optic modulator. 45 ps pulses are amplified to ten’s of watt peak power and propagated through a standard polarization maintaining fiber to reach enough spectral broadening by self-phase-modulation. Pulses are then compressed down to about 500 femtoseconds with a grating compressor. We analyse the measured spectral broadening with respect to pulse repetition rate and average power and do some comparison with numerical simulations. This approach paves the way to versatile ultrashort pulse Lasers that could be easily synchronized.
11665-45
Author(s): Andrey Petrov, ITMO Univ. (Russian Federation); Grigory Mikhailovsky, Alexander Gorbatchev, Peter the Great Saint-Petersburg Polytechnic Univ. (Russian Federation); Maxim A. Odnoblyudov, Ampliconyx Oy (Finland), Peter the Great Saint-Petersburg Polytechnic Univ. (Russian Federation); Mikhail Kozlyakov, Peter the Great Saint-Petersburg Polytechnic Univ. (Russian Federation); Joona Rissanen, Ampliconyx Oy (Finland); Regina Gumenyuk, Tampere Univ. (Finland); Valery Filippov, Ampliconyx Oy (Finland)
Digital Forum: On-demand
Show Abstract + Hide Abstract
We present compact high peak power (over 1 MW) and high energy (over 60 µJ) fiber-based laser system delivering 50 ps pulses with narrow linewidth less than 0.1 nm at 1064 nm based on a gain-switched DFB laser diode and an active tapered fiber amplifier. The efficient second harmonic generation enables to obtain more that 30 W of green light with 0.1 nm linewidth.
Session 9: Coherent Beam Combination Fiber Lasers
11665-47
Author(s): Di Lin, Univ. of Southampton (United Kingdom); Joel Carpenter, The Univ. of Queensland (Australia); Yutong Feng, Yongmin Jung, Saurabh Jain, Yujung Feng, Michalis N. Zervas, David J. Richardson, Univ. of Southampton (United Kingdom)
Digital Forum: On-demand
Show Abstract + Hide Abstract
We describe an approach capable of generating structured light beams from a compact laser source based on the coherent combination of multiple tailored Gaussian beams emitted from a multicore fiber (MCF) amplifier. We report a proof-of-concept structured light generation experiment, using a cladding-pumped 7-core MCF amplifier as an integrated parallel amplifier array and a spatial light modulator to actively control the amplitude, polarization and phase of the signal light input to each fiber core. We demonstrate the generation of various structured light beams including high-order linearly polarized spatial fiber modes, cylindrical vector beams and helical phase front optical vortex beams.
11665-48
Author(s): Henning Stark, Joachim Buldt, Michael Müller, Friedrich-Schiller-Univ. Jena (Germany); Arno Klenke, Friedrich-Schiller-Univ. Jena (Germany), Helmholtz-Institut Jena (Germany); Jens Limpert, Friedrich-Schiller-Univ. Jena (Germany), Helmholtz-Institut Jena (Germany), Fraunhofer-Institut für Angewandte Optik und Feinmechanik IOF (Germany)
Digital Forum: On-demand
Show Abstract + Hide Abstract
We present a coherently-combined ytterbium-doped fiber CPA laser system directly emitting pulses with 106 fs duration at a pulse energy of 910 µJ and an average power of 910 W. The system is based on coherent beam combination of 16 ytterbium-doped large mode area rod-type fiber amplifiers. By using extensive spectral amplitude and phase shaping in the fiber-integrated frontend, the CPA system emits a spectrum with a 10dB-bandwidth exceeding 30 nm and thus generates the corresponding short compressed pulses.
11665-49
Author(s): Jean-Christophe Chanteloup, Lab. pour l'Utilisation des Lasers Intenses (France), CNRS (France), Ecole Polytechnique (France); Severine Bellanger, Lab. pour l'Utilisation des Lasers Intenses (France), Ecole Polytechnique (France); Louis Daniault, Lab. pour l'Utilisation des Lasers Intenses (France), Lab. d'Optique Appliquée (France); Ihsan Fsaifes, Matthieu Veinhard, Lab. pour l'Utilisation des Lasers Intenses (France), Ecole Polytechnique (France); Jérôme Bourderionnet, Christian Larat, Eric Lallier, Arnaud Brignon, Thales Research & Technology (France)
Digital Forum: On-demand
Show Abstract + Hide Abstract
We present achievements of a 61 channels Tiled-aperture Coherent Beam Combining femtosecond fiber laser as a digital laser. Tiled-aperture indeed offers unrivaled agility in terms of far field beam shaping. We experimentally illustrate it shall be considered as a digital laser where the near field electric field amplitude and phase could be controlled at what one would call the pixel (a single beam) level. When applying a helicoidal phase distribution, we show that Orbital Angular Momentum beams with characteristic donut shape transverse distributions can be generated. kW average power operation as well as non-linear regime performances will be displayed.
11665-50
Author(s): Pierre Bourdon, Hermance Jacqmin, Béatrice Augère, Anne Durécu, Didier Goular, Bastien Rouzé, Roland Domel, Didier Fleury, Christophe Planchat, Laurent Lombard, ONERA (France)
Digital Forum: On-demand
Show Abstract + Hide Abstract
We developed a laser testbed coherently combining seven 1.5-µm fiber lasers through active phase control in a target-in-the-loop (TIL) configuration, with a detection sub-system designed to achieve coherent combining on the target. In this paper, we present the results of the outdoor experimental campaign where the testbed is operated, with distance to the target varying from 15 meters to 1 km. Efficient atmospheric turbulence compensation is demonstrated, confirming that TIL coherent combining can be achieved, even when very strong turbulence are observed.
11665-51
Author(s): Felix Wellmann, Laser Zentrum Hannover e.V. (Germany); Nina Bode, Max-Planck-Institut für Gravitationsphysik (Germany); Michael Steinke, Laser Zentrum Hannover e.V. (Germany); Fabian Meylahn, Benno Willke, Max-Planck-Institut für Gravitationsphysik (Germany); Ludger Overmeyer, Laser Zentrum Hannover e.V. (Germany), Leibniz Univ. Hannover (Germany); Peter Wessels, Jörg Neumann, Dietmar Kracht, Laser Zentrum Hannover e.V. (Germany)
Digital Forum: On-demand
Show Abstract + Hide Abstract
Gravitational wave detectors require single-frequency laser sources with challenging requirements regarding beam quality and noise properties. We developed a reliable single-frequency fiber amplifier architecture based on standard step-index large-mode-area fibers and coherently combined two high power beams to enable further power scaling. A combined power of 391 W could be achieved with a combining efficiency of approx. 92 %. The TEM00-mode content of the combined beam was analyzed and a higher-order-mode content of 6.8 % was measured. This yields 365 W linearly polarized output power in the TEM00-mode that is usable for the application.
11665-52
Author(s): Bastien Rouzé, Jérôme Primot, ONERA (France); Frédéric Zamkotsian, Patrick Lanzoni, Aix-Marseille Université, CNRS, CNES, LAM - Laboratoire d'Astrophysique de Marseille (France); Cindy Bellanger, ONERA (France)
Digital Forum: On-demand
Show Abstract + Hide Abstract
PISTIL (PISton and TILt) interferometry is a segmented wavefront metrology technique that can fulfill the role of being an independent phase analyzer for tiled laser arrays used in coherent beam combining (CBC). It presents a plug-and-play characteristics enabling others research or industrial applications such as metrology of segmented mirrors, MOEMS or measurement standards. It can operate onto complex optical benches. Alongside the PISTIL concept, we developed methods for phase extraction and meta-analysis, with best accuracy to rightfully address an end user needs in term of segmented wavefront diagnosis. We demonstrate those functionalities onto the HIBISCUS optical testbed equipped with a segmented mirror, specifically designed test data analysis pipelines and improve the control-command based on PISTIL wavefront analysis. In the current configuration, it can emulate CBC near field piston and tilt variations.
Session 10: Novel Fiber Sources
11665-53
Author(s): Sven Hochheim, Eike Brockmüller, Peter Wessels, Laser Zentrum Hannover e.V. (Germany); Joona Koponen, nLight Oy (Finland); Tyson Lowder, nLight Inc. (United States); Steffen Novotny, nLight Oy (Finland); Jörg Neumann, Dietmar Kracht, Laser Zentrum Hannover e.V. (Germany)
Digital Forum: On-demand
Show Abstract + Hide Abstract
Specialty fibers such as chirally-coupled-core fibers show a high potential for further power scaling of single-frequency fiber amplifiers. For the first time, we demonstrate a spliceless all-fiber amplifier, where all optical components are directly integrated in a single Yb3+-doped 3C®-fiber. Such a spliceless laser design allows a compact and robust architecture using specialty fibers, while maintaining excellent beam properties. At an output power of 336W, a fundamental mode content of 90.4% at a PER above 13 dB was measured without an onset of SBS, TMI or other parasitic effects. This work emphasizes the suitability of 3C®-fibers in high-power laser systems.
11665-54
Author(s): Kilian Le Corre, iXblue SAS (France); Hervé Gilles, Sylvain Girard, Ctr. de Recherche sur les Ions, les Matériaux et la Photonique (France); Alexandre Barnini, Louanne Kervella, Pascal Guitton, Thierry Robin, iXblue SAS (France); Giorgio Santarelli, Lab. Photonique, Numérique et Nanosciences, Institut d'Optique Graduate School (France); Mathieu Laroche, Ctr. de Recherche sur les Ions, les Matériaux et la Photonique (France)
Digital Forum: On-demand
Show Abstract + Hide Abstract
We present in this work, the development of a nanosecond pulsed Master-Oscillator Power-Amplifier (MOPA) laser system near 905 nm based on the 3-level transition of Neodymium using a novel low NA polarization-maintaining Nd-doped silica fiber with a 30µm core and 130µm cladding. The MOPA delivered up to 24 W of average power (0.6 mJ energy per pulse) with good beam quality (M²~1.4). Cascaded LBO and BBO crystals are used respectively for second-harmonic generation and fourth-harmonic generation, giving respectively average output powers of 4.9W at 452nm (conversion efficiency of 20%) and 550mW at 226nm (conversion efficiency of 10%).
11665-55
Author(s): Tomonari Kawamura, Akira Shirakawa, The Univ. of Electro-Communications (Japan)
Digital Forum: On-demand
Show Abstract + Hide Abstract
Multicore Photonic Crystal Fiber (MC-PCF) have multiple cores close to each other, which allows coherent beam combining (CBC). MC-PCF can scale the output power by increasing the number of cores by CBC if the in-phase mode is selected. We demonstrate simultaneous realization of phase-locked and mode-locked laser by using Yb-doped 7-core MC-PCF by a semiconductor saturable absorber placed in the near-filed inside a resonator. High energy 333 nJ pulses were obtained directly from a mode-locked fiber laser oscillator at a 42.4 MHz repetition rate with an average power of 14.1 W at 24 W excitation. We observed the direct output pulse duration of 52 ps by assuming a sech2 profile. However, it may be noise-like pulses because of no variation when we performed pulse compression. Single-pulse operation was achieved by increasing the bandwidth of intracavity filter. At this time, 129 nJ, 42.4 MHz pulses were generated with a 5.5 W average power and the direct output pulse duration of 42 ps.
11665-56
Author(s): Muhammad A. Arshad, Arni Pratiwi, Alexander Hartung, Matthias Jäger, Leibniz-Institut für Photonische Technologien e.V. (Germany)
Digital Forum: On-demand
Show Abstract + Hide Abstract
We report on the observation of a new phenomenon, occurring in a fiber ring laser. This phenomenon describes the transition from an initially bidirectional emission of a reciprocal fiber ring laser to a unidirectional emission at a certain pump power threshold. In addition, the final direction is not predefined but appears to be randomly chosen every time the threshold is exceeded. Therefore, we term this new phenomenon as direction instability. In addition we provide a first discussion of how the pump power threshold and the final direction can be influenced by the length and the loss of the cavity.
Session 11: Nover Fibers for Laser Applications
11665-58
Author(s): Albrecht Steinkopff, Cesar Jauregui, Christopher Aleshire, Arno Klenke, Jens Limpert, Friedrich-Schiller-Univ. Jena (Germany)
Digital Forum: On-demand
Show Abstract + Hide Abstract
In this work we will examine and optimize the power and energy scaling potential for different coherently-combined multicore fiber designs. In order to do so a simulation tool is used to model the amplification process under consideration of thermally induced effects. Particular attention is paid to the mitigation of non-uniform mode shrinking at the fiber end facet together with an increase of the combining efficiency. With an optimized design almost 10 kW instead of 3 kW with a 6x6 MCF and 80 µm cores can be achieved. Additionally, we will present a detailed study on such fibers being used for ultrashort pulse systems.
11665-59
Author(s): Baoluo Zheng, Jinhang Wang, Penghui Yan, Xin Zhang, Wenju Lu, Pu Wang, Beijing Univ. of Technology (China)
Digital Forum: On-demand
Show Abstract + Hide Abstract
A silica leakage channel microstructured optical fiber (LCMOF) is firstly drawn from a 3D printed preform. The LCMOF realized the optical signal transmission of supercontinuum spectrum from 600 nm to 1650 nm and the measured propagation loss is 15 dB/m at 632 nm and 19.5 dB/m at 1064 nm. The bending loss is 5 dB/m with 15 cm radius and 7.3 dB/m with 5 cm radius. The refractive index fluctuation is less than 7×10^-4 in the fiber core region. The structure of LCMOF can be adjusted effectively by altering the pre-designed preform and optimizing drawing temperature, which result in the less defects and lower loss.
11665-60
Author(s): Gonzalo Palma-Vega, Fraunhofer-Institut für Angewandte Optik und Feinmechanik IOF (Germany), Friedrich-Schiller-Univ. Jena (Germany); Christian Hupel, Johannes Nold, Stefan Kuhn, Fraunhofer-Institut für Angewandte Optik und Feinmechanik IOF (Germany); Jens Limpert, Fraunhofer-Institut für Angewandte Optik und Feinmechanik IOF (Germany), Friedrich-Schiller-Univ. Jena (Germany), Helmholtz-Institut Jena (Germany); Nicoletta Haarlammert, Thomas Schreiber, Fraunhofer-Institut für Angewandte Optik und Feinmechanik IOF (Germany)
Digital Forum: On-demand
Show Abstract + Hide Abstract
In this work, we present a simplified method for manufacturing microstructured optical fibers, which was applied for an Yb-doped pentagonal large pitch fiber (LPF). Instead of using the classical stack & draw technique, which can become time-consuming and delicate, we used a one-step structuring of the cladding via deep-hole drilling in glass. The Yb-doped core was also realized in one-step by gas phase doping via MCVD. Additional nanostructuring steps of the core material were redundant due to the the high radial homogeneity of the refractive index achieved, matched with high precision to the refractive index of the glass cladding. Numerical simulations were used to verify the method and analyze the scaling of the fiber towards larger mode field diameters, which is crucial for further scaling the power in fiber lasers.
11665-61
Author(s): Andrei Fedotov, Tampere Univ. (Finland); Vasilii Ustimchik, Joona Rissanen, Teppo Noronen, Ampliconyx Oy (Finland); Regina Gumenyuk, Tampere Univ. (Finland); Yuri Chamorovskii, Kotel'nikov Institute of Radio Engineering and Electronics of RAS (Fryazino branch) (Russian Federation); Alexander Kolosovskii, Victor Voloshin, Igor Vorobev, Kotelnikov Institute of Radio Engineering and Electronics (Russian Federation); Valery Filippov, Ampliconyx Oy (Finland)
Digital Forum: On-demand
Show Abstract + Hide Abstract
We developed ytterbium-doped double-clad large mode area (MFD = 30 µm) spun tapered fibers with low internal birefringence and perfect beam quality (M2 < 1.2). Picosecond MOPA system (95ps/100 MHz, 1064 nm) based on proposed active tapered fiber with output average power of 64 W (gain 32 dB) is demonstrated.
11665-62
Author(s): Svetlana S. Aleshkina, Tatiana Kochergina, Mikhail Bubnov, Vladimir V. Velmiskin, Fiber Optics Research Ctr. (Russian Federation); Mikhail V. Yashkov, Mikhail Yu. Salganskii, G. G. Devyatykh Institute of Chemistry of High-Purity Substances (Russian Federation); Mikhail E. Likhachev, Fiber Optics Research Ctr. (Russian Federation)
Digital Forum: On-demand
Show Abstract + Hide Abstract
We demonstrate possibility of spectrally selective fundamental core mode suppression in a single-mode fiber. It was done by modification of the silica cladding - high-index absorbing rods were inserted in it. Appropriate choice of the rods parameters allowed us to realize rectangular fundamental mode suppression region and to control its spectral bandwidth by bending.
11665-63
Author(s): Xin Zhang, Beijing Univ. of Technology (China); Shoufei Gao, Yingying Wang, Wei Ding, Jinan Univ. (China); Pu Wang, Beijing Univ. of Technology (China)
Digital Forum: On-demand
Show Abstract + Hide Abstract
High-power fiber lasers have experienced a dramatic development over the last decade. Further increasing the output power needs an upscaling of the fiber mode area, while maintaining a single-mode output. Here, we propose an all-solid anti-resonant fiber (ARF) structure, which ensures single mode operation in broadband by resonantly coupling high order modes (HOMs) into the cladding. A series of fibers with core sizes ranging from 40 to 100 µm are proposed exhibiting maximum mode area exceeding 5000 µm2. Numerical simulations show this resonant coupling scheme provides a HOMs suppression ratio more than 20 dB, while keeping the fundamental mode loss lower than 1 dB/m. The proposed structure also exhibits high tolerance for core index depression.
Session 12: Special Session I: TMI in Photonics
Session 13: Special Session II: TMI in Industry
11665-75
Author(s): John M. Ballato, Thomas W. Hawkins, Clemson Univ. (United States); Nanjie Yu, Peter D. Dragic, University of Illinois at Urbana-Champaign (United States)
Digital Forum: On-demand
Show Abstract + Hide Abstract
Power demands from high beam quality fiber-based lasers have reached levels where nominally weak optical nonlinearities now limit continued scalability. Amongst the parasitic nonlinearities, transverse mode instability (TMI) is especially problematic because it is the dominant scaling limitation. To manage optical nonlinearities, the fiber laser community has singularly focused on large mode area (LMA) designs to spread the optical power out over a larger cross-sectional area and reduce the effective intensity to increase nonlinear thresholds. Such LMA designs are necessarily multimode and, so, TMI, while not necessarily predictable, was not surprising in hindsight. This paper will focus on an alternative and complementary approach; one where nonlinearities are managed materially through understanding and judicious design of the glass compositions from which the fiber is comprised.
11665-76
Author(s): Clemens Hönninger, Amplitude Systèmes (France)
Digital Forum: On-demand
Session P: Poster Session
11665-64
Author(s): Hao Tian, Chaodu Shi, Wei Shi, Quan Sheng, Shuai Sun, Junxiang Zhang, Jianquan Yao, Tianjin Univ. (China)
Digital Forum: On-demand
Show Abstract + Hide Abstract
In this paper the simulation and experiment on spectral linewidth when using triangle-shape pulse in Yb-doped nanosecond fiber amplifier was demonstrated. In simulation, triangle-shape pulses with the same pulse width but different rise times have different linewidths. And their spectrum will be differently broadened by self-phase modulation (SPM). According to this principle, we built a Yb-doped nanosecond fiber amplifier with triangle-shape pulse in master oscillator power amplifier (MOPA) configuration. It was found that the law of the spectral linewidth change is almost consistent with the theoretical calculation.
11665-65
Author(s): Clement Guyonnet, Ecole Polytechnique de l'Univ. d'Orléans (France); Alexandre Amavigan, Wiktor Walasik, Robert E. Tench, Jean-Marc Delavaux, Cybel LLC (United States); Thierry Robin, Benoit Cadier, Arnaud Laurent, Patrice Crochet, iXblue Photonics (France)
Digital Forum: On-demand
Show Abstract + Hide Abstract
Tunable narrow linewidth single frequency lasers in the 2000 nm region are important as sources for mid-IR generation, LIDAR, DWDM, and coherent systems, and infrared spectroscopy and gas sensing applications. In this paper we report the design and experimental performance of a tunable packaged PM Watt-level TDFL. Our device is built in a compact self-contained package that is suitable for integration into system applications or laboratory experimental setups. We employ a novel uncooled 940 nm semiconductor laser pumping arrangement in our TDFL source. We study the output power and optical signal-to-noise ratio (OSNR) of the tunable laser source over a wide tuning range of 1880—2050 nm.
11665-67
Author(s): Mehmet Dogan, Richard H. Chin, Jonah H. Jacob, Science Research Lab., Inc. (United States); Aland K. Chin, Somerville Laser Technology, LLC (United States)
Digital Forum: On-demand
Show Abstract + Hide Abstract
Beam-combinable, high-power, narrow-linewidth Yb-doped fiber amplifiers are presently being evaluated as high energy laser weapons where the rapid turn-on of the amplifiers is critical. These amplifiers are optically pumped at the narrow 976nm, high-absorption peak of ytterbium. The fiber amplifier turns on when the emission spectra of the diode pump modules significantly overlap the 976nm Yb absorption peak. The thermal wavelength tuning behavior of two types of laser diode sources was analyzed to predict the cold-start turn-on-time of a fiber amplifier. Turn-on-times of ~4ms and ~4s were predicted for a fiber amplifier employing a laser diode bar directly attached to a micro-channel cooler and a single emitter package cooled by a cold plate, respectively.
11665-68
Author(s): Gizem Alpakut, Burcin Unlu, Bogaziçi Üniv. (Turkey); Seydi Yavas, Bogaziçi Üniv. (Turkey), Lumos Lazer A.S. (Turkey)
Digital Forum: On-demand
Show Abstract + Hide Abstract
We demonstrated a tunable wavelength and bandwidth fiber laser oscillator and a simple tuning mechanism using an aperture to obtain femtosecond pulses. By further characterization and the optimization, we believe the system will be an important femtosecond pulse source for high power systems to initiate the pulses from a desired wavelength to match the bandwidth and central wavelength prerequisites for >100 Watt level systems.
11665-69
Author(s): Masanori Nishiura, Tatsutoshi Shioda, Saitama Univ. (Japan)
Digital Forum: On-demand
Show Abstract + Hide Abstract
We report superiorities of an ANDi PM fiber laser incorporating a dual-color band-pass filter(dual-BPF) instead of an ordinal single color BPF. The fiber laser has a low self-starting threshold and starts mode-locking quickly. Shorter BPF component induces Q-switching and the longer one keeps stable mode-locked lasing. Once the laser starts mode-locking, the sorter BPF component does not affect the mode-locked lasing. The laser produces various of pulses by just changing longer BPF’s values, for example, the center wavelength, bandwidth, shape, and attenuation. This dual-BPF technique can be applied to not only NALM-based fiber lasers but also various types of mode-locked lasers.
11665-70
Author(s): Alexandre Amavigan, Shivaraman Asoda, Robert E. Tench, Jean-Marc Delavaux, Cybel LLC (United States); Thierry Robin, Benoit Cadier, Arnaud Laurent, iXblue Photonics (France)
Digital Forum: On-demand
Show Abstract + Hide Abstract
Current progress in infrared LIDAR, atmospheric sensing, and DWDM transmission system experiments highlights the need for large bandwidth, high dynamic range polarization-maintaining (PM) optical amplifiers in the 1900 nm—2100 nm band. In this paper we present the first simulated and experimental results for a newly developed miniature packaged Ho-doped fiber amplifier that is optimized for operation at 2100 nm. We will present comprehensive simulations and experimental data for this 2100 nm HDFA illustrating its successful long wavelength operation. Watt-level output powers will be demonstrated for the miniature packaged amplifier.
Front Matter: Volume 11665
Conference Chair
Michalis N. Zervas
Optoelectronics Research Ctr. (United Kingdom)
Conference Co-Chair
Cesar Jauregui-Misas
Friedrich-Schiller-Univ. Jena (Germany)
Program Committee
Coherent | Nufern (Australia)
Program Committee
Raytheon Co. (United States)
Program Committee
Clemson Univ. (United States)
Program Committee
U.S. Army Combat Capabilities Development Command (United States)
Program Committee
Heike Ebendorff-Heidepriem
The Univ. of Adelaide (Australia)
Program Committee
Air Force Research Lab. (United States)
Program Committee
Northrop Grumman Aerospace Systems (United States)
Program Committee
Deutsches Elektronen-Synchrotron (Germany)
Program Committee
OFS Fitel, LLC (United States)
Program Committee
Macquarie Univ. (Australia)
Program Committee
Coherent | Nufern (United States)
Program Committee
nLIGHT, Inc. (United States)
Program Committee
Martin Dybendal Maack
NKT Photonics A/S (Denmark)
Program Committee
MIT Lincoln Lab. (United States)
Program Committee
Martin H. Muendel
Lumentum (United States)
Program Committee
IPG Photonics Corp. (United States)
Program Committee
Lockheed Martin Aculight Corp. (United States)
Program Committee
Fraunhofer-Institut für Angewandte Optik und Feinmechanik IOF (Germany)
Program Committee
Luminar Technologies, Inc. (United States)
Program Committee
U.S. Naval Research Lab. (United States)
Program Committee
Tianjin Univ. (China)
Program Committee
Paul Steinvurzel
The Aerospace Corp. (United States)
Program Committee
Ctr. for Nano Science and Engineering (CeNSE) (India)
Program Committee
Beijing Univ. of Technology (China)
Program Committee
Amplitude Systèmes (France)
Program Committee
Pu Zhou
National Univ. of Defense Technology (China)
Additional Information
This conference does not accept post-deadline abstracts for oral presentation.

Support for Authors from Low-Income Economies
Based on availability of sponsorship funds, reduced registration fees or partial travel support may be available for presenting authors from low-income countries whose submissions are accepted. If you wish to apply, please contact SPIE (JenL@SPIE.org) after notification of paper acceptance. Include your SPIE paper number, name, and amount/type of support requested. Requests will be accepted through October 2020 for Photonics West 2021.