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Conference 12871
Laser Resonators, Microresonators, and Beam Control XXVI
30 January - 1 February 2024
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Session 1:
Microcomb General using Microresonators
30 January 2024 • 8:00 AM - 10:00 AM PST | Moscone Center, Room 103 (Level 1 South Lobby)
Session Chair:
Andrea M. Armani, The Univ. of Southern California (United States)
12871-1
Nonlinear chalcogenide microresonator devices
(Invited Paper)
30 January 2024 • 8:00 AM - 8:30 AM PST | Moscone Center, Room 103 (Level 1 South Lobby)
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Nonlinear chalcogenide microresonators and microspheres are an ideal platform to explore nonlinear optical effects in a compact footprint. Chalcogenide glasses are particularly attractive, with high nonlinearities and long wavelength transparency. Applications including, cascaded Brillouin generation, photosensitive control, sensing and frequency comb generation.
12871-2
30 January 2024 • 8:30 AM - 8:50 AM PST | Moscone Center, Room 103 (Level 1 South Lobby)
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Cylindrical micro-resonators with normal dispersion are seen to support photonic snake states. These are a type of two-dimensional zig-zag solitonic wave arising via the control of the well-known snaking instability, discovered 50 years ago and ever since observed as an uncontrollable one in classical and quantum fluids, Bose-Einstein condensates, chemical reactions, and optics, amongst others. The spectrum of Photonic snakes is a two-dimensional continuous collection frequency combs featuring heterogeneity and intrinsic synchronisation. The conditions for their existence, robustness, and deterministic excitation routes are identified. Applications such as spectroscopy, metrology, or communications may benefit by this new paradigm of micro-comb formation.
12871-3
30 January 2024 • 8:50 AM - 9:10 AM PST | Moscone Center, Room 103 (Level 1 South Lobby)
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The on-chip generation of coherent light has wide-ranging applications in metrology, spectroscopy, quantum optics, etc. In this study, we demonstrate the generation of coherent light from a Silicon-Nitride microring resonator using cascade nonlinear processes. These involve a telecom pump laser and its efficiently generated second harmonic through the photogalvanic effect. By leveraging second- and third-order nonlinear effects such as harmonic generation, (non-)degenerate four-wave mixing, and optical parametric amplification, we achieve the generation of UV, visible, and near-infrared light. This study highlights the potential of Silicon-Nitride integrated photonics in producing broad-spectrum light sources at wavelengths beyond the capabilities of conventional lasers.
12871-4
30 January 2024 • 9:10 AM - 9:30 AM PST | Moscone Center, Room 103 (Level 1 South Lobby)
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We present a terahertz-carrier frequency comb based on Kerr-induced synchronization (KIS) of an optical frequency comb (OFC), wherein a commercially-available C-band laser harnesses an OFC tooth and captures the repetition rate (frep) of the OFC. The linear relationship between the C-band laser modulation and the OFC frep modulation enables direct transfer of the C-band laser frequency to the OFC frep. In addition, the large KIS effect bandwidth facilitates frep tuning over a wide range of frequencies. This work addresses the THz gap by providing a direct path for millimeter wave generation, utilizing CMOS-compatible fabrication techniques and off-the-shelf components.
12871-5
30 January 2024 • 9:30 AM - 10:00 AM PST | Moscone Center, Room 103 (Level 1 South Lobby)
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Recent works have demonstrated how silicon nitride integrated photonics can be endowed with photoinduced second-order nonlinearities for efficient frequency conversion. Here we will showcase how highly-efficient second-harmonic generation in a microresonator can be combined with self-injection locking to a DFB laser to create a standalone dual-wavelength displaying high output power, conversion efficiency and hertz-level coherence in an integrated fashion. We will also cover how the photoinduced nonlinearity can trigger cascaded effects, expanding the operation range and functionality of the microresonator, and discuss how silicon nitride microrings can be further mode engineered to provide combined high efficiency and wide tunability of the nonlinear processes.
Session 2:
Soliton Generation with Microresonators
30 January 2024 • 10:30 AM - 12:30 PM PST | Moscone Center, Room 103 (Level 1 South Lobby)
Session Chair:
Vladimir S. Ilchenko, Jet Propulsion Lab. (United States)
12871-6
Driven solitons in passive and active resonators
(Invited Paper)
30 January 2024 • 10:30 AM - 11:00 AM PST | Moscone Center, Room 103 (Level 1 South Lobby)
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Driven solitons are currently attracting a lot of attention both for their fundamental interest and potential applications in metrology and spectroscopy
In this talk, I will discuss our recent results on novel driven solitons such as active solitons (in a laser cavity pumped below the lasing threshold), parametrically driven solitons (both quadratically and cubically driven) as well as soliton trapped in a phase modulation potential.
12871-7
30 January 2024 • 11:00 AM - 11:20 AM PST | Moscone Center, Room 103 (Level 1 South Lobby)
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We investigate the dynamics of Kerr cavity solitons under intracavity phase modulation in the normal dispersion regime. The introduction of a parabolic potential leads to the emergence of multimode resonances, facilitating the formation of higher-order bright solitons. As the potential strength is gradually reduced, these bright solitons undergo a transition into dark solitons. This transition can be described as a shift from a multimode resonance to a collapsed snaking bifurcation structure. Our study provides a thorough exploration of cavity dynamics and presents a promising approach to accessing multi-stable states by effectively manipulating the phase modulation.
12871-8
30 January 2024 • 11:20 AM - 11:40 AM PST | Moscone Center, Room 103 (Level 1 South Lobby)
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We show that in the Kerr-Induced Synchronization (KIS) regime, an external reference pump laser allows for the control of the opposite (in frequency) dispersive Wwave (DW) power and frequency, through self-balancing of the cavity soliton. We report an increase of more than 20~dB of the DW of an octave-spanning comb at 780 nm, with a reference pump in the telecom C-band, while tuning of the DW over three comb teeth. Our work paves the way for significant improvement of the carrier-envelope offset frequency detection of octave-spanning combs.
12871-9
From synchronization to syntonization of a dissipative Kerr soliton to an external optical reference
30 January 2024 • 11:40 AM - 12:00 PM PST | Moscone Center, Room 103 (Level 1 South Lobby)
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We demonstrate that a dissipative Kerr soliton comb tooth can be captured by another injected pump laser, resulting in Kerr induced synchronization. This regime is highly significant for metrology applications, where the soliton can passively lock onto a reference clock laser. The dynamics of the system also enable other forms of locking, where the comb tooth is captured at a fixed offset from the reference laser, entering the syntonization regime. Similar to breather entrainment, we establish that the syntonization frequency offset correlates with the soliton's repetition rate.
12871-10
30 January 2024 • 12:00 PM - 12:30 PM PST | Moscone Center, Room 103 (Level 1 South Lobby)
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We demonstrate high frequency stability, low phase noise photonic oscillator based on optical self-injection locked laser pumping of silicon nitride integrated microresonator comb (microcomb), and frequency locking of comb teeth to temperature insensitive high finesse Fabry Perot cavity.
Session 3:
Microresonators I
30 January 2024 • 2:00 PM - 3:30 PM PST | Moscone Center, Room 103 (Level 1 South Lobby)
Session Chair:
Andrea M. Armani, The Univ. of Southern California (United States)
12871-11
Nanophotonic interfaces to atomic systems
(Invited Paper)
30 January 2024 • 2:00 PM - 2:30 PM PST | Moscone Center, Room 103 (Level 1 South Lobby)
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We demonstrate the versatility of dielectric metasurfaces as a compact, efficient and multifunctional platform to trap single atoms in a tweezer trap, and an ensemble of atoms in a magneto-optical-trap (MOT) for various AMO applications.
12871-12
30 January 2024 • 2:30 PM - 2:50 PM PST | Moscone Center, Room 103 (Level 1 South Lobby)
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Adiabatic frequency conversion (AFC) in microresonators offers phase-matching-free and intensity-independent conversion efficiency of 100 %, even at the single-photon level. However, it is not used in application so far. We demonstrate AFC-based FMCW-LiDAR with a whispering gallery resonator made of lithium niobate. We achieve electro-optically-induced 700-MHz-wide frequency chirps with over 99 % linearity down to 90 ns chirp times. Applying these chirps, we successfully determine distances between 0.5 and 5 m with a 10 cm resolution. Future chip-integration could significantly enhance the performance and increase the distance resolution by more than one order of magnitude.
12871-13
30 January 2024 • 2:50 PM - 3:10 PM PST | Moscone Center, Room 103 (Level 1 South Lobby)
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Quantum microcombs result from the generation entangled twin-photons states via spontaneous four-wave mixing in resonantly pumped microresonators with Kerr nonlinearity. Here we show that that it is possible to provide a full description of this open quantum system that allows one to evaluate metrics such as purity, fidelity entropy, and higher-order correlations.
12871-14
30 January 2024 • 3:10 PM - 3:30 PM PST | Moscone Center, Room 103 (Level 1 South Lobby)
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Nonlinear frequency generation is demonstrated in silicon nitride photonics using microring resonators with engineered dispersion through a Bragg grating perturbation. The processes by which these nonlinear effects occur introduces backscattered light, due to bidirectionally-propagating hybridized modes. Such backscattered light is often detrimental to the pump laser and imposes a limit on the power that can be delivered to the ring system, reducing the operating range of ring resonators for nonlinear light generation. We mitigate these effects with an on-chip passive optical isolator, which protects the pump laser from backscattered light, allowing for higher pump power operation regimes. Furthermore, we introduce a recycling channel that allows for power to be re-pumped into the mirroring resonator to enable controllable exploration into more interesting nonlinear optics phenomena.
Session 4:
Microresonators II
30 January 2024 • 4:00 PM - 5:40 PM PST | Moscone Center, Room 103 (Level 1 South Lobby)
Session Chair:
Vladimir S. Ilchenko, Jet Propulsion Lab. (United States)
12871-15
Quantum photonics in silicon carbide microresonators: multimode and multi-emitter correlations
(Invited Paper)
30 January 2024 • 4:00 PM - 4:30 PM PST | Moscone Center, Room 103 (Level 1 South Lobby)
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Silicon carbide as a host material uniquely combines CMOS compatible photonics with high-quality optically interfaced qubits and strong optical nonlinearities. In this talk, I will discuss the use of silicon carbide microresonators to explore multimode correlations built through spontaneous pair generation via the optical nonlinearity as well as all-to-all coupling of quantum emitters. I will discuss opportunities to use inverse design and as well as classical cavity design methods for engineering these correlations.
12871-16
30 January 2024 • 4:30 PM - 4:50 PM PST | Moscone Center, Room 103 (Level 1 South Lobby)
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We present a methodology to distinguish between absorptive and scattering losses in SiN optical waveguide resonators by measuring the thermo-optic redshift in resonant wavelength and deducing absorption losses using thermal properties determined through the differential 3ω method. This information offers researchers valuable insights for improving device performance and optimizing fabrication processes. We demonstrate results on the effect of a 650oC thermal anneal on R=120um whispering-gallery mode microring resonators fabricated using N-rich PECVD SiN with n=1.92 at 800nm, which reduced total losses from 1.4dB/cm to 0.64dB/cm at 780nm and yielded an intrinsic-Q of 1.1 million, due primarily to decreased absorption losses.
12871-17
30 January 2024 • 4:50 PM - 5:10 PM PST | Moscone Center, Room 103 (Level 1 South Lobby)
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Commonly, the spectra of high Q-factor microresonators are fixed or only weakly tunable, which limits their versatility. To address this limitation, we demonstrate continuous tunability of the axial free spectral range (FSR) of parabolic microresonators created by bending a 125 μm radius optical fiber segment. By controlling the bent fiber profile with linear stages affixed to its ends, we vary its FSR between 1.9 pm and 2.7 pm for more than 65 equally spaced eigenmodes. We show that the FSR tunability can be achieved with precision better than 0.2 pm. The demonstrated tunability, together with the inherently small FSR of our parabolic microresonators, unlock their potential applications including optical frequency comb generation and frequency conversion.
12871-18
Solid and liquid whispering-gallery mode microresonators excited via Lorenz-Mie scattering and their applications
(Invited Paper)
30 January 2024 • 5:10 PM - 5:40 PM PST | Moscone Center, Room 103 (Level 1 South Lobby)
Show Abstract +
Whispering-gallery mode microresonators excited via free-space scattering are described along with their applications and sensing uses
Posters-Tuesday
30 January 2024 • 6:00 PM - 8:00 PM PST | Moscone Center, Room 2003 (Level 2 West)
Conference attendees are invited to attend the LASE poster session on Tuesday evening. Come view the posters, enjoy light refreshments, ask questions, and network with colleagues in your field. Authors of poster papers will be present to answer questions concerning their papers. Attendees are required to wear their conference registration badges to the poster sessions.
Poster Setup: Tuesday 10:00 AM - 5:00 PM
Poster authors, view poster presentation guidelines and set-up instructions at http://spie.org/PW/poster-presentation-guidelines.
Poster Setup: Tuesday 10:00 AM - 5:00 PM
Poster authors, view poster presentation guidelines and set-up instructions at http://spie.org/PW/poster-presentation-guidelines.
12871-42
30 January 2024 • 6:00 PM - 8:00 PM PST | Moscone Center, Room 2003 (Level 2 West)
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We report a high power Yb:YAG thin disk laser with cylindrical vector polarization incorporating an intracavity S-waveplate. By adjusting the angle of the S-waveplate in the resonator, we could select a cylindrical vector polarization state of the laser output, radial or azimuthal polarization, in the Yb:YAG thin disk laser resonator. The laser yielded >10 W of both radial or azimuthal polarized output for incident pump power of 131 W in continuous-wave mode of operation, corresponding to the slope efficiency of>18%. Output characteristics will be discussed in detail.
12871-43
30 January 2024 • 6:00 PM - 8:00 PM PST | Moscone Center, Room 2003 (Level 2 West)
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This paper presents tactile feedback chips based on PDMS and micro optical WGM sensors for compliance control in humanoid robots. We focus on their application in our humanoid robot, GUCnoid 1.0. The chips provide high-resolution tactile sensing capabilities, allowing real-time adjustments and enhancing the robot's dexterity. Fabricated using PDMS, the chips can conformally integrate with the robot's surface. The micro optical WGM sensors offer exceptional sensitivity and fast response, enabling accurate measurement of contact forces and object properties. Experimental results demonstrate their effectiveness in precise and safe interactions. This technology has the potential to advance the field of robotics, enabling more versatile and intelligent humanoid robots.
12871-44
30 January 2024 • 6:00 PM - 8:00 PM PST | Moscone Center, Room 2003 (Level 2 West)
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The software for visualization and comparison of the scattering phase functions is developed. The utility allows to calculate, display and compare the scattering diagrams of a monochromatic visible range laser radiation that scatters on a spherical dielectric particle. The comparative analysis of the angle characteristics of the Mie and Henyey-Greenstein phase functions is provided.
12871-45
30 January 2024 • 6:00 PM - 8:00 PM PST | Moscone Center, Room 2003 (Level 2 West)
Show Abstract +
Atmospheric turbulence causes refractive index fluctuations that introduce extra distortions to the wavefront of the propagated radiation. It degrades the resolution of the telescope for imaging applications and reduces the radiation power density in focusing applications. One of the possible ways of research the impact of the turbulence is to numerically simulate the spectrum of refractive index fluctuations, to reproduce it using a wavefront corrector and to measure the resultant wavefront using a Shack–-Hartmann sensor. In this paper, we developed turbulence simulator software that generates the sequence of phase screens with Kolmogorov spectra. We reconstructed the generated set of phase screens using a stacked-actuator deformable mirror.
12871-46
30 January 2024 • 6:00 PM - 8:00 PM PST | Moscone Center, Room 2003 (Level 2 West)
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A multispectral wavefront sensor can be used to perform a single-shot spatio-temporal characterization of a laser pulse. In order to measure the spatio-spectral electric field, a laser pulse can be spectrally modulated, separated and measured by a wavefront sensor. In order to simplify the experimental setup and hardware control, the single wavefront sensor can be used. In this research we discuss the development of the multi-channel wide-aperture high-resolution Shack-Hartmann sensor for multispectral wavefront sensing. The whole sensor area of 15×15 mm was divided into 4 logical apertures, each for separate laser beam. The development and calibration procedure are described. The wavefront sensor control software is developed and tested.
Session 5:
Microresonator Stabilization
31 January 2024 • 8:00 AM - 10:00 AM PST | Moscone Center, Room 103 (Level 1 South Lobby)
Session Chair:
Andrea M. Armani, The Univ. of Southern California (United States)
12871-19
Optimized encoding for coherent communication using photonic crystal cavity IQ modulators in thin film lithium niobate
(Invited Paper)
31 January 2024 • 8:00 AM - 8:30 AM PST | Moscone Center, Room 103 (Level 1 South Lobby)
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Thin film lithium niobate (TFLN) photonic integrated circuits offer several improvements over other platforms in terms of material loss, energy efficiency, and operational bandwidth. We review our recent demonstration of quadrature phase shift keying in an ultrasmall TFLN photonic crystal-based IQ modulator. Our modulator features a footprint of 40 x 200 um^2 along with quality factors approaching 10^5 providing it with a V_pi = 1.16 V [H. Larocque et al. CLEO 2023, paper STh1R.3]. We discuss extension to and optimization of quadrature amplitude modulation encoding schemes tailored to the device’s voltage response, including the use of an autoencoder neural network for streamlining bit error rate minimization.
12871-20
31 January 2024 • 8:30 AM - 8:50 AM PST | Moscone Center, Room 103 (Level 1 South Lobby)
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Narrow linewidth lasers with high stability are a key enabling technology in high-impact applications such as quantum technologies. Stabilizing such lasers requires the design of efficient Proportional-Integral-Derivative (PID) controllers. However, high end applications require PID controllers with very high regulation bandwidth, relocking feature and easy to adjust parameters. In order to tackle this design challenge, we implemented the pipeline technique in the design of our PID controller. This allowed us to improve the sample rate at which the controller operates. The designed PID has been successfully used in a VBG based external-cavity diode lasers for laser stabilization with ultra-narrow linewidth.
12871-21
31 January 2024 • 8:50 AM - 9:10 AM PST | Moscone Center, Room 103 (Level 1 South Lobby)
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Stable lasers are crucial for many coherent optical systems. Electro-optic laser frequency stabilization methods, like the Pound-Drever-Hall (PDH) technique, has been widely used to stabilize a laser frequency. However, there has been a trade-off between complexity, power consumption, and noise detection sensitivity. Here, a modulation-free laser stabilization technique is proposed and experimentally demonstrated on a silicon photonic chip which breaks this trade-off. The proposed architecture utilizes an integrated cavity-coupled Mach-Zehnder interferometer as a frequency noise discriminator which significantly simplifies the architecture while offering the same sensitivity as the well-known PDH technique. The implemented photonic integrated circuit occupies an area of 0.456 mm2 and is integrated on AIM Photonics 180 nm silicon-on-insulator process.
12871-22
31 January 2024 • 9:10 AM - 9:30 AM PST | Moscone Center, Room 103 (Level 1 South Lobby)
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We present a system of two coupled resonators that reduces thermal effects on comb states through controllable mode crossings. This system demonstrates increased thermal resilience through an increase in the lifetime of soliton state when mode frequencies in auxiliary resonator approach degeneracy with the main resonator. This approach can be used to reduce thermorefractive phase noise in soliton microcombs.
12871-47
31 January 2024 • 9:30 AM - 10:00 AM PST | Moscone Center, Room 103 (Level 1 South Lobby)
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Optical photons are excellent quantum information carriers, but weak optical nonlinearity poses significant challenges to the scalability and computational capabilities of these systems. Currently, only probabilistic methods can achieve nonlinear quantum operations crucial for universality and fault tolerance, restricting the clock speed and making it challenging to scale due to significant resource overhead. Ultrafast quantum nanophotonics with second-order optical nonlinearity presents a potential solution to overcome these challenges.
In this talk, we will discuss recent experimental advances, including the on-chip generation and measurement of ultra-broadband squeezed states, all-optical realizations of switching and nonlinear functions for ultrafast feedforward operations, and widely tunable optical parametric oscillators in an emergent thin-film lithium niobate on insulator platform. We further delve into how the enhanced optical nonlinearity can enable novel functionalities such as photon-number-resolving measurements and deterministic quantum state engineering, offering a practical path to scalable, fault-tolerant quantum information processors room-temperature.
Session 6:
Laser Beam Control
31 January 2024 • 10:30 AM - 12:10 PM PST | Moscone Center, Room 103 (Level 1 South Lobby)
Session Chair:
Vladimir S. Ilchenko, Jet Propulsion Lab. (United States)
12871-23
31 January 2024 • 10:30 AM - 10:50 AM PST | Moscone Center, Room 103 (Level 1 South Lobby)
Show Abstract +
This research introduces a novel two-dimensional beam steering mechanism for wireless optical power transfer systems, utilizing diverging angular dispersion laser beams and resonant beam charging. Our approach achieved faster scanning times, lower error pixel rates, and extended resonant beam charging maintenance times than conventional pencil beam systems. Experimental results demonstrate that our method achieved 1.5 times faster scanning times, 1.2 times lower error pixel rates, and three times longer continuous resonant cavity charging. These improvements enhance the efficiency, precision, and reliability of wireless optical power systems, making our approach a promising advancement in beam steering technology.
12871-24
31 January 2024 • 10:50 AM - 11:10 AM PST | Moscone Center, Room 103 (Level 1 South Lobby)
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Employing two novel beam attenuation and ghost suppression schemes, a compact, high-power laser beam CMOS based profiler has been realized. Wherein we reduce the number of optics involved to measure a continuous laser power of more than 1 kilowatts from a traditional 6 wedge prism pairs to only 3 optics and at a fraction of the size.
12871-25
31 January 2024 • 11:10 AM - 11:30 AM PST | Moscone Center, Room 103 (Level 1 South Lobby)
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We have developed an inhibited-coupling HCPCF (IC-HCPCF) with a record-low transmission loss of <50 dB/km at 266 nm, showcasing solarization resistance. Our 2-meter-long patchcord with SMA terminations, tested for UV handling and lifespan, achieved a 93% transmission rate when a 266 nm wavelength laser beam was injected. Stable for over 100 hours, with power fluctuations less than 2.6%, this is the first long-lasting, high-energy DUV laser fiber guidance.
12871-26
31 January 2024 • 11:30 AM - 11:50 AM PST | Moscone Center, Room 103 (Level 1 South Lobby)
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We introduce a highly efficient method for generating multiple beam spots using multimode interference within single mode fiber – square core fiber (SMF-SCF) structures. By adjusting the length of SCF, we can create various beam spot configurations, such as 4x4, 3x3 and 2x2 , providing enhanced flexibility. Extensive simulations and experimental validation at a wavelength of 1060 nm were conducted to investigate the relationship between beam position, number, and intensity. Our technique can also produce multiple beams in rectangular or hexagonal lattices by modifying fiber core shape accordingly. Furthermore, we explored the generation of multiple higher order modes (HOMs) when the input beam is a symmetric HOM. To showcase its practical application, we utilized our proposed structure at the output end of a high peak power pulse laser amplifier, highlighting the advantages of multiple beams in high-power scenarios. In conclusion, the SMF-SCF structure presents significant potential for efficient generation of multiple beam spots, opening up various opportunities in photonics and laser technology.
12871-27
31 January 2024 • 11:50 AM - 12:10 PM PST | Moscone Center, Room 103 (Level 1 South Lobby)
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Spatial beam self-cleaning in graded-index multimode fibers, involves a nonlinear transfer of power among the fiber modes, which leads to robust bell-shaped output beams. The resulting output mode power distribution can be described by statistical mechanics arguments. Although the spatial coherence of the output beam was experimentally demonstrated, there is no direct study of modal phase evolutions. Based on a holographic mode decomposition method, we reveal that nonlinear spatial phase-locking occurs between the fundamental and its neighboring low-order modes, in good quantitative agreement with theoretical predictions.
Session 7:
Laser Beam Shaping I
31 January 2024 • 1:40 PM - 3:30 PM PST | Moscone Center, Room 103 (Level 1 South Lobby)
Session Chair:
Andrea M. Armani, The Univ. of Southern California (United States)
12871-28
The detrimental period chirp of holographic gratings: Its origin, measurement, effects on pulse compressors, and its elimination
(Invited Paper)
31 January 2024 • 1:40 PM - 2:10 PM PST | Moscone Center, Room 103 (Level 1 South Lobby)
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We present a comprehensive investigation of the period chirp, a detrimental effect originating from the lithographic step in the fabrication of holographic gratings. Starting from the origin of the period chirp we discuss its measurement, its effects on the compressed pulses when chirped gratings are used in pulse compressors, and finally, we show possible ways to eliminate the period chirp directly in the fabrication.
12871-29
31 January 2024 • 2:10 PM - 2:30 PM PST | Moscone Center, Room 103 (Level 1 South Lobby)
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In this report, we demonstrate two novel fundamental notions in the counter-propagating nonlinear interaction scheme, namely mode rejection and all-optical gratings. We consider a probe forward signal (FS) and a counter-propagating backward control beam (BCB) that are launched at the opposite ends of a multimode and multicore fibre. When both the FS and the CB are in a strong nonlinear regime, a FS with arbitrary modal state undergoes the suppression of a specific spatial mode that is fixed by the CB, which we name mode rejection. When the FS and the CB are respectively in a weak and a strong nonlinear regime, the CB plays the role of an all-optical grating for the FS. This dynamics is exploited to achieve key-all optical operations for the multimode platform, including tuneable power splitting, power combining, and power switching.
12871-30
31 January 2024 • 2:30 PM - 2:50 PM PST | Moscone Center, Room 103 (Level 1 South Lobby)
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To achieve the maximum fluence and minimize the damage of the lasers at the National Ignition Facility (NIF), the uniformity across the laser beam profile is critically important. NIF amplifiers are pumped by banks of flashlamps, resulting in a non-uniform total amplifier gain profile. Two amplitude masks are used to pre-compensate the input laser beam to make the final beam as flat as possible and create shadows to protect the optics downstream resulting in substantial energy loss. Instead, we use programable phase modulation to achieve the same goals with better uniformity and negligible energy loss.
12871-31
31 January 2024 • 2:50 PM - 3:10 PM PST | Moscone Center, Room 103 (Level 1 South Lobby)
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A new reference-less method for measuring the transmission matrix of a multimode optical fiber (MMF) from speckled intensity measurements is investigated both numerically and experimentally. It is based on a machine learning technique that uses a mini-batch gradient descent algorithm. We validated numerically the accuracy of the method by computing the predicted complex field transmitted by the MMF. For a 700-mode fiber, the Pearson correlation coefficients reach respectively 99.95% and 99.6% at the MMF output and at the corresponding Fourier plane. The high accuracy of the prediction was also confirmed experimentally paving the way for 3D beam shaping through MMFs.
12871-32
31 January 2024 • 3:10 PM - 3:30 PM PST | Moscone Center, Room 103 (Level 1 South Lobby)
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A filament forms through a balance of self-focusing (Kerr effect) and plasma self-defocusing. The heat generated as the electron-ion recombine produces a cylindrical shock wave behind which a low density channel is formed. High energy UV filaments are used to study the shock wave by shadowgraphy. The shock is seen to start supersonic, before transitioning after microseconds to a constant velocity acoustic wave. Computational models of the gas-dynamics evolution are presented that agree with a well known empirical formula for shockwave velocity, as well as with experimental observations. We determine the profile of induced changes to the refractive index of air due to these thermal effects. Our aim is to predict the proper vortex filament creating a parabolic index of refraction that can serve as a waveguide for successive filaments.
Session 8:
Laser Beam Shaping II
31 January 2024 • 4:00 PM - 5:50 PM PST | Moscone Center, Room 103 (Level 1 South Lobby)
Session Chair:
Vladimir S. Ilchenko, Jet Propulsion Lab. (United States)
12871-33
31 January 2024 • 4:00 PM - 4:30 PM PST | Moscone Center, Room 103 (Level 1 South Lobby)
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Laser-based secondary sources of radiation in the soft X-ray and EUV range have the potential for imaging at the smallest spatial and temporal scales, given their wavelength range and ultrashort duration (fs or under). Recently novel degrees of freedom of light beam manipulation have been extended into the high intensity regime, to enhance their emissivity or expand their capability. We have used these pulse shaping techniques to generate coherent EUV sources, where High Harmonics from laser-gas interaction are seen to reproduce IR wavefront shaping and can generate light tubes with Orbital Angular Momentum using EUV optics. At close to relativistic intensities, we have performed simulations that show that structured laser pulses can also improve the performance of incoherent plasma-based X-ray sources. The outcomes of these simulations, as well as optimisation strategies and applications, will be presented.
12871-34
31 January 2024 • 4:30 PM - 4:50 PM PST | Moscone Center, Room 103 (Level 1 South Lobby)
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Beam shaping has gained increasing importance in laser-based processing, offering enhanced efficiency, quality, and precision across various applications. This paper discusses the challenges of characterizing and defining criteria for evaluating shaped beams in laser material processing. It highlights the essential role of beam shaping in continuous wave (CW) processes like high-quality welding for e-mobility and pulsed applications like surface texturing. Various beam shaping technologies are explored, and criteria such as efficiency, uniformity, sharpness, robustness, and depth of field are proposed for evaluating beam performance. Proper characterization and evaluation of shaped beams are crucial to optimize laser performance, ensuring reliable and repeatable outcomes in laser-based processes.
12871-35
31 January 2024 • 4:50 PM - 5:10 PM PST | Moscone Center, Room 103 (Level 1 South Lobby)
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We experimentally reveal a so-far unnoticed high-power limit to spatial beam self-cleaning in graded-index nonlinear
multimode optical fibers. As the optical pulse power is progressively increased, we observed that the initial Kerr-induced beam clean-up and associated improvement of the spatial beam quality are eventually spolied. Based on a holographic mode decomposition of the output field, we show that this beam degradation can be described in a thermodynamic approach to wave propagation as a manifestation of "high-temperature" thermalization, which depletes the fundamental mode in favour of a highly multimodal power distribution
12871-36
31 January 2024 • 5:10 PM - 5:30 PM PST | Moscone Center, Room 103 (Level 1 South Lobby)
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Control over the parameters of a laser beam such as intensity and phase provides an important basis of modern photonics. Established control schemes, however, cover only a limited parameter range.
We employ intense ultrasound fields in ambient air, enabling control of laser light in extreme parameter regimes. We acousto-optically modulate ultrashort pulses at 1030 nm with a peak power of 20 GW efficiently (> 50%) in ambient air. We further show excellent beam profile conservation and separability of diffracted and transmitted beams.
Finally, our approaches show that light control can prospectively be translated from solid-state media to the gas phase by means of intense ultrasound, considerably widening the scope of established light control methods.
12871-37
31 January 2024 • 5:30 PM - 5:50 PM PST | Moscone Center, Room 103 (Level 1 South Lobby)
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Laser locking is a crucial technique in various scientific applications, especially in the field of atomic physics, where the laser's frequency must correspond to the narrow linewidth of atomic transitions. This work aims to leverage the advantages of 3D printed push-fit slots to achieve an inexpensive, compact, and highly customizable optical setup for locking lasers between two upper atomic transitions. In our approach, the optical components are mounted in custom 3D printed slots instead of traditional optical posts to decrease costs and overall size. The error signal is then created by an electromagnetically induced transparency (EIT) signal in a two-photon dichroic atomic vapor laser lock (T-P DAVLL), corresponding to the 6S1/2, 6P1/2, and 8S1/2 states of Cesium. This research was undertaken thanks in part to funding from the Canada First Research Excellence Fund.
Session 9:
Optical Sensors
1 February 2024 • 8:30 AM - 10:10 AM PST | Moscone Center, Room 103 (Level 1 South Lobby)
Session Chair:
Andrea M. Armani, The Univ. of Southern California (United States)
12871-38
Determination of a refractive index distribution along a SNAP microresonator from its single spectrum: temperature distribution measurement
(Invited Paper)
1 February 2024 • 8:30 AM - 9:00 AM PST | Moscone Center, Room 103 (Level 1 South Lobby)
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We show, both theoretically and experimentally, that it is possible to determine a nonuniform temperature distribution along a SNAP microresonator from a single measurement of its spectrum. In our experiment, we use a silica microcapillary containing a SNAP microresonator. The microcapillary is filled with water and locally heated with a moving heating source (light-pumped microfiber) introducing the temperature distribution parameterized as T(z)=T_0 exp(-|z-z_Q+iw|/L), where z is the coordinate along the microcapillary axis, z_Q is the heating source position, and w≪L is the width of the source. At each heating source position z_Q, we restore the parameters of this distribution from the SNAP microresonator spectrum. Our theoretical calculations are in a good agreement with the experimental data.
12871-39
Optimizing bipedal locomotion in humanoid robots using micro-optical resonators and machine learning
1 February 2024 • 9:00 AM - 9:20 AM PST | Moscone Center, Room 103 (Level 1 South Lobby)
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This paper introduces a pioneering lower bipedal locomotor humanoid equipped with micro optical sensors. The robot exploits these sensors to achieve enhanced stability and adaptability in its locomotion. Real-time sensory feedback allows the robot to dynamically adjust gait and balance control algorithms for efficient bipedal movement across diverse terrains. Machine learning algorithms optimize locomotion patterns for human-like motion and energy efficiency. The robot's lightweight, durable design enables navigation in complex environments, making it a potential candidate for various real-world applications. Experimental evaluations demonstrate the significant advancements in stability and precision over conventional bipedal humanoid robots, showcasing the potential of micro optical sensors in revolutionizing humanoid robotics.
12871-40
1 February 2024 • 9:20 AM - 9:40 AM PST | Moscone Center, Room 103 (Level 1 South Lobby)
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This paper presents a novel approach to improve the sensitivity of Linear Variable Differential Transformers (LVDTs) by integrating micro optical Whispering Gallery Mode (WGM) sensors. By leveraging the unique characteristics of WGM sensors, including high sensitivity and compact size, the proposed method enables more precise and accurate measurements in LVDT systems. Experimental results demonstrate a significant enhancement in sensitivity, leading to finer resolution and improved performance. The compact size of micro optical sensors allows for seamless integration into existing LVDT designs. This research has promising implications for high-precision metrology and sensing applications in robotics, aerospace, automotive, and biomedical engineering fields.
12871-41
1 February 2024 • 9:40 AM - 10:10 AM PST | Moscone Center, Room 103 (Level 1 South Lobby)
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Due to the local nature of the interactions in nonlinear photonic topological insulators, attempts to describe their topology using traditional band structure approaches are not suitable. Here, we develop a general framework for classifying the topology of nonlinear materials. Using the so-called spectral localizer to define local topological markers, we provide a quantitative definition of topologically non-trivial nonlinear modes that are distinguished by the appearance of a topological interface surrounding the mode. Moreover, we show how the spectral localizer can be used to probe the time-evolution of nonlinearly induced topological domains within a system.
Conference Co-Chair
Institute of Dynamics of Geospheres RAS (Russian Federation)
Program Committee
Institute for Research in Electronics & Applied Physics (United States), Univ. of Maryland, College Park (United States)
Program Committee
Harvard John A. Paulson School of Engineering and Applied Sciences (United States)
Program Committee
Nicolás Quesada
Polytechnique Montréal (Canada)
Program Committee
Okinawa Institute of Science and Technology Graduate Univ. (Japan)