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    Green Photonics Presentations

    Laser-assisted Manufacturing and Micro/Nano Fabrication
    (ordered chronologically by session start time)

    Quantum dot mode locked lasers for coherent frequency comb generation
    Paper 8993-9

    Author(s):  Anthony Martinez, Lab. de Photonique et de Nanostructures (France), et al.
    Conference 8993: Quantum Sensing and Nanophotonic Devices XI Session 1: New Laser Sources
    Date and Time: 2/2/2014 9:25AM

    The inhomogeneous gain broadening and the ultrafast absorption recovery dynamics of 1.55 µm InAs/InP quantum dash self-pulsating lasers are an asset for short pulse generation. The weak coupling of amplified spontaneous emission with the guided modes leads to low timing jitter. The flat optical spectrum combined with the 10 kHz-narrow RF beat note linewidth represent a promising technology for optical frequency comb generation. Coherence between spectral modes was assessed by means of spectral phase measurements. The parabolic spectral phase profile indicates that short pulses can be obtained provided the intracavity dispersion can be compensated by inserting a single mode fiber.

    Laser-based synthesis of nanoparticles: role of laser parameters and background conditions
    Paper 8969-4

    Author(s):  Tatiana E. Itina, Lab. Hubert Curien (France), et al.
    Conference 8969: Synthesis and Photonics of Nanoscale Materials XI Session 1: Laser-based Nanomaterials Synthesis and Real-Time Diagnostics
    Date and Time: 2/2/2014 2:10PM

    Laser ablation (LA) is a unique tool for nanoparticle synthesis [1]. The main advantages of this method are in its green character and in the possibility of a control over particle size. In this study, we examine nanoparticle formation by laser ablation under different experimental conditions and analyse the results based on the developed models [1-4]. The dynamics of the laser plume expansion is examined revealing the role of the background pressure and laser pulse duration (fs, ns). As a result, the ablated material is compressed and a part of it becomes supersaturated. The so-called “primary” nanoparticles are formed at this stage. Then, nanoparticle aggregation/fragmentation enters into play leading to the formation of the secondary particles. In addition, laser-assisted fragmentation of nanopraticles is also examined. Based on numerical modeling we shed light on the above mechanisms by using different numerical approaches, such as molecular dynamics, DSMC [4], numerical hydrodynamics [3] and analytical analysis [2]. Calculations are performed mostly for metallic targets and for carbon under different background conditions. The obtained results explain recent experimental findings and help to predict the role of the experimental parameters. The performed analysis thus indicates ways of a control over nanoparticle synthesis. [1]T. E. Itina, N. Bouflous, J. Hermann, P. Delaporte, SPIE Proc., 8414, DOI: 10.1117 /12.923129 (2011). [2]T. E. Itina and A. Voloshko, Appl. Phys. B, DOI: 10.1007/s00340-013-5490-6 (2013). [3]M. E. Povarnitsyn, T. E. Itina, P. Levashov, K. Khishchenko, Phys. Chem. Chem. Phys., 15, 3108-3114, DOI: 10.1039/C2CP42650A (2013) [4]T. E. Itina, K. Gouriet, L. V. Zhigilei, S. Noel, J. Hermann, and M. Sentis, Appl. Surf. Sci. , 253, 7656-7661, DOI: 10.1016/j.apsusc.2007.02.034 (2007)

    GaAsBi/GaAs semiconductor lasers: initial laser characteristics and future prospects
    Paper 9002-6

    Author(s):  Stephen J. Sweeney, Univ. of Surrey (United Kingdom), et al.
    Conference 9002: Novel In-Plane Semiconductor Lasers XIII Session 2: New Materials and Grating Controlled
    Date and Time: 2/3/2014 10:30AM

    The addition of Bismuth to III-V alloys gives rise to improved band structure offering reduced non-radiative losses and improved temperature stability for near- and mid-infrared devices. For GaAsBi/GaAs devices, experiments show that an optimum bandstructure may be achieved with ~9% Bismuth with <1% strain. Initial results on the first electrically-pumped room temperature GaAsBi/GaAs lasers will be discussed where we report Jth ~ 800A/cm2 for SQW devices containing 2.2% Bi. Lasing is also reported at low temperature for devices containing 3.9% Bi. The limitations of current devices and prospects for device optimisation will be discussed in more detail at the conference.

    Laser-induced patterns on metals and polymers for biomimetic surface engineering
    Paper 8967-4

    Author(s):  Anne-Marie Kietzig, McGill Univ. (Canada), et al.
    Conference 8967: Laser Applications in Microelectronic and Optoelectronic Manufacturing (LAMOM) XIX Session 2: Laser-induced Modification and Patterning of Surfaces II: Joint Session with Conferences 8967 and 8969
    Date and Time: 2/3/2014 11:00AM

    Specific functionalities of natural surfaces can often be attributed to the surface’s chemical composition, its microstructure, its organized or random roughness and hence the resulting surface wetting and adhesion character. This study shows how surface features on titanium and PTFE appear and change with fs-laser irradiation intensity. While Ti surfaces show rigid micrometer-scaled features with superimposed nanostructures, PTFE exhibits elastic hairy structures of nanometric diameter, which upon a certain threshold tend to bundle to larger features. By a strategic choice of experimental settings both surface patterns can be adjusted to mimic wetting and flow behaviour as seen with natural examples.

    Micro optics for laser diode beam shaping
    Paper 8965-32

    Author(s):  Manfred Jarczynski, LIMO Lissotschenko Mikrooptik GmbH (Germany), et al.
    Conference 8965: High-Power Diode Laser Technology and Applications XII Session 7: High Power Diode Laser Optics
    Date and Time: 2/3/2014 2:00PM

    Micro optics is well-known for beam shaping inside of diode lasers. Collimation or etendue matching are one operation area, homogenizing and field or line generation another one. We present laser diode optimized approaches of fast axis collimation considering advantages of high refractive index glasses and addressing beam steering approaches for best etendue treatment. Several applications do not only need high brightness, but also specially shaped beams like homogeneous lines or fields. Two principle zoom setups for adjustable laser lines are figured out: A classical telescope setup with moveable lenses and a patent pending approach based on moved arrays of micro lenses. Moderate line length from 4 to 60mm, contrasts below 7% and efficiencies over 80% are achieved in simulation and application.

    High-power fiber lasers in geothermal, oil and gas
    Paper 8961-12

    Author(s):  Mark S. Zediker, Foro Energy, Inc. (United States), et al.
    Conference 8961: Fiber Lasers XI: Technology, Systems, and Applications Session 3: Applications
    Date and Time: 2/3/2014 2:40PM

    The subject of this paper is the requirements, design, fabrication, and testing of a prototype laser rock drilling system capable of penetrating even the hardest rocks found deep in the earth. Most oil producing reservoirs are located in or below relatively soft rock formations, however, with the growing need for energy, oil companies are now attempting to drill through very hard surface rock and deep ocean formations with limited success. This paper will discuss the types of laser suitable for this application, the requirements for putting lasers in the field, the technology needed to support this laser application and the test results of components developed specifically by Foro Energy for the drilling application.

    Highly efficient and compact free beam kW-diode laser modules
    Paper 8965-34

    Author(s):  Jens Meinschien, LIMO Lissotschenko Mikrooptik GmbH (Germany), et al.
    Conference 8965: High-Power Diode Laser Technology and Applications XII Session 7: High Power Diode Laser Optics
    Date and Time: 2/3/2014 2:40PM

    The application of highly specific laser beam shape gain increasing importance, especially for diode lasers. The first choice of beam shape is not anymore always circular instead line or rectangular field geometries are very often of favourable interest. The characteristics of broad area laser diode bars in conjunction with cylindrical shaped optics are powerful for the design of very compact configurations to generate high brightness and highly homogenous fields. The design and performance data of several systems in the kW power range are evaluated. A distinct unique approach of line configuration is shown which allows scalability in terms of line length and also the switching on and off of line segments. Special emphasis is given on the beam shaping itself. Several more line configurations are presented which also include systems with wavelength in the extended NIR spectral range, e.g. 1470 nm or 1950 nm.

    Nanolasers with 3D Nanocavities
    Paper 8980-14

    Author(s):  Yeshaiahu Fainman, Univ. of California, San Diego (United States), et al.
    Conference 8980: Physics and Simulation of Optoelectronic Devices XXII Session 4: Metal Nanocavities
    Date and Time: 2/3/2014 3:50PM

    In this paper we will describe design, fabrication and testing of a new family of nanocavities confined in space all three dimensions (3D) . Specific designs of 3-D nanocavities such as composite metal-dielectric-semiconductor composites in various geometries (e.g., cylindrical, coaxial, etc. ) will be discussed.

    Spectroscopy-based photonic instrumentation for the manufacturing industry: contactless measurements of distances, temperatures, and chemical compositions
    Paper 8992-26

    Author(s):  Bertrand Noharet, Acreo Swedish ICT AB (Sweden), et al.
    Conference 8992: Photonic Instrumentation Engineering Session 6: Laser-based Photonic Instrumentation II
    Date and Time: 2/3/2014 4:00PM

    The steady progress in photonic components in terms of cost-to-performance ratio, maturity and robustness opens new avenues for the commercial deployment of photonic sensor systems in a wide range of industrial applications. Advanced sensing can be used to optimize processes and thereby enable significant savings in energy consumption. Three cases of robust photonic instrumentation for process optimization and quality control in manufacturing industries are presented, including insights in design and calibration procedures, as well as results from field experiments: improved metal recycling with LIBS, quality control in precision machining by white-light interferometry, and remote temperature measurements in harsh environments.

    DFB interband cascade lasers for tunable laser absorption spectroscopy from 3 to 6 µm
    Paper 8993-44

    Author(s):  Michael von Edlinger, nanoplus GmbH (Germany), et al.
    Conference 8993: Quantum Sensing and Nanophotonic Devices XI Session 8: Integrated and Discrete Mid-IR Optoelectronics
    Date and Time: 2/3/2014 4:25PM

    Tunable Laser Absorption Spectroscopy in the mid-infrared wavelength region, especially between 3 and 6 µm, is of great interest for high performance gas sensing applications. Interband Cascade Lasers can provide monomode continuous wave (cw) emission above room temperature in this wavelength range. We present the simulation, design and manufacturing of application-grade distributed feedback laser devices based on this concept. The fabricated devices successfully target specific, technologically relevant, wavelengths in cw operation above room temperature with low energy consumption. Output powers above 5 mW, high Side Mode Suppression Ratio around 30 dB and tuning ranges of up to13 nm were achieved.

    Optical and electrical characterization of surface passivation of GaAs nanosheets
    Paper 8996-13

    Author(s):  Shermin Arab, The Univ. of Southern California (United States), et al.
    Conference 8996: Quantum Dots and Nanostructures: Synthesis, Characterization, and Modeling XI Session 4: Nanostructure Characterization
    Date and Time: 2/3/2014 4:30PM

    GaAs nanostructures are used in optoelectronic applications including solar cells, LEDs and fast electronics. Although GaAs shows outstanding optical properties, it suffers from surface states and consequently high surface recombination velocity. The surface depletion effects lead to semi-insulating behaviors in GaAs devices. Passivation of GaAs nanostructures with large band gap semiconductors (AlGaAs) lead to surface stability and improvement in optoelectronic properties. Due to inherent high twin defects, the side wall facets of GaAs nanowires usually consist of (111)A and (111)B micro-facets which could be difficult to passivate. On the other hand, twin-free GaAs nanosheetsgrown by metal organic chemical vapor deposition (MOCVD) may have different passivation effect since the enclosed facets of nanosheets are all atomic flat (110) facets. Based on opto-electric response improvement in passivated GaAs nanowire, we are interested in the performance of passivated nanosheet. We provide a systematic study to compare the opto-electrical improvement after AlGaAs passivation of GaAs nanosheets. Secondary electron scanning electron microscopy (SE-SEM) contrast imaging is used to characterize the composition and doping. Spacial mapping of Raman shows Raman peaks corresponding to GaAs and AlAs. Both room temperature and low temperature photoluminescent (PL) indicates increase in optical responses of nanosheet after passivation (100X). Electron beam induced current (EBIC) measurements reveal the diffusion length of carries in passivated vs. non-passivated nanosheets. EBIC mapping also reveals a pn junction formed along the boundary between the base and overgrowth regions of nanosheet. Finally, time-resolved PL shows a carrier lifetime increase after passivation in nanosheets.

    How small can one shrink a semiconductor laser and is it worth it?
    Paper 8996-15

    Author(s):  Jacob B. Khurgin, Johns Hopkins Univ. (United States), et al.
    Conference 8996: Quantum Dots and Nanostructures: Synthesis, Characterization, and Modeling XI Session 5: Quantum Dot Emission
    Date and Time: 2/4/2014 10:30AM

    There is a growing interest in increasing density of integration of optical components, passive and active, but there is a natural barrier looming ahead – the diffraction limit, but it can be overcome by introducing metallic strictures, albeit at the cost of increasing loss. This loss may in principle be compensated by gain in semiconductor medium, opening ways for development of sub-wavelength nanolaser (spaser). In this talk we consider how the characteristics of laser change when it size is shrunk below the diffraction limit, and show that, rather counter-intuitively, the threshold current does not decrease with the size, as the slope efficiency decreases, while the linewidth broadens, and the operational speed does not improve by much relative to the same size LED. Therefore the distinction between sub-wavelength LED and laser is quite insignificant from the practical point of view.

    Characteristics of the heat resistant FBG sensor under laser cladding condition
    Paper 8963-7

    Author(s):  Akihiko Nishimura, Japan Atomic Energy Agency (Japan), et al.
    Conference 8963: High-Power Laser Materials Processing: Lasers, Beam Delivery, Diagnostics, and Applications III Session 2: Laser Surface Treatment
    Date and Time: 2/4/2014 11:10AM

    We successfully fixed the heat resistant FBG sensor by metal mold. The FBG sensor was made by femtosecond laser processing. A Quasi-CW laser to weld a filler wire was used. An optical fiber was set under the filler wire beforehand. Then it was heated by the laser pluses, partially to be soaked in a weld pool. The FBG sensor was buried at 2 mm depth over the length of 1 cm. The FBG sensor can detect the vibration of the plate caused by impact shocks. No degradation on its reflection spectra was detected before and after laser cladding condition.

    Direct laser writing with a spatial light modulator
    Paper 8974-22

    Author(s):  Min Gu, Swinburne Univ. of Technology (Australia), et al.
    Conference 8974: Advanced Fabrication Technologies for Micro/Nano Optics and Photonics VII Session 7: 3D Printing: STED and SLM
    Date and Time: 2/4/2014 3:50PM

    We will report on our recent progress on direct laser writing with a spatial light modulator. Direct laser writing (DLW) has been widely adopted in nanophotonics, in particular to generate three-dimensional (3D) structures at micro and nano scales. However, there are a few challenges in 3D DLW. First, the effect of the mismatch of refractive indices between the immersion medium of a high numerical-aperture objective and the bulk material where a 3D micro/nano-structure is fabricated becomes a dominant factor to determine the functionality of the devices. The fabrication speed is significantly affected by the operation with a single focal spot. We show how these two issues can be overcome with a spatial light modulator. As a result, 3D DLW can be operated in high refractive-index nonlinear media and its fabrication speed can be increased by two orders of magnitude.

    Optically-active hybrid nanostructures: Exciton-plasmon interaction and injection of hot plasmonic electrons
    Paper 8996-23

    Author(s):  Alexander Govorov, Ohio Univ. (United States), et al.
    Conference 8996: Quantum Dots and Nanostructures: Synthesis, Characterization, and Modeling XI Session 7: Nanomaterials
    Date and Time: 2/4/2014 4:00PM

    Excitons and plasmons in nanocrystals strongly interact via Coulomb and electromagnetic fields and this interaction leads to characteristic interference effects which can be observed in optical spectra. Along with the effects of Coulomb interaction, Fermi-sea electrons of metal nanocrystals can be optically injected to a neighboring semiconductor electrode. A size of metal nanocrystal, type of metal, and orientation of the external electric field are important to obtain high quantum efficiencies of generation and injection of plasmonic electrons. The results obtained in this study can be used to design nano-devices based on the Coulomb and tunnel interactions for various opto-electronic applications.

    Influence of Laser Parameters on Quality of Microholes and Process Efficiency
    Paper 8967-16

    Author(s):  Anne Feuer, Univ. Stuttgart (Germany), et al.
    Conference 8967: Laser Applications in Microelectronic and Optoelectronic Manufacturing (LAMOM) XIX Session 8: Ultrashort Pulse Micromachining: Joint Session with Conferences 8967 and 8972
    Date and Time: 2/4/2014 4:30PM

    To enable the direct-spinning process of super-micro fibres (< 0.5 dtex) suitable for novel medical, hygienical and technical products microhole arrays with diameters down to 25 µm in very high quality are required. The process time for a single microhole ranges up to several ten seconds. Simple energy balance considerations show that higher averaged powers - either achieved with larger pulse energies or an increased repetition rate - considerable reduce the process time. In this case plasma formation and heat accumulation show increased formation of melt and recast. Thus, the objective is to increase the productivity while maintaining consistent quality of the microholes.

    Numerical simulation of III-nitride lattice-matched structures for THz QC lasers
    Paper 8980-28

    Author(s):  Sara Shishehchi, Boston Univ. (United States), et al.
    Conference 8980: Physics and Simulation of Optoelectronic Devices XXII Session 7: III-Nitride-based Optoelectronics
    Date and Time: 2/4/2014 4:40PM

    Nitride semiconductors are promising for the development of THz quantum cascade lasers (QCLs). Properly designed QC structures enable terahertz emission at room temperature however, this is more challenging than conventional structures due to the spontaneous and piezoelectric polarizations and the lattice mismatch. The use of lattice matched layers based on InAln or InAlGaN is an alternative which mitigates the effect of polarization and enables growing thicker layers due to the higher structural quality. We present a comparison between GaAs/AlGaAs and GaN/InAl(Ga)N terahertz QC structures based on a Monte-Carlo study of carrier dynamics to highlight the improvements offered by lattice matched structures.

    High contrast research in the Nd:glass laser system based on optical parametric amplification temporal cleaning device
    Paper 8962-21

    Author(s):  Xiaoming Lu, Shanghai Institute of Optics and Fine Mechanics (China), et al.
    Conference 8962: High Energy/Average Power Lasers and Intense Beam Applications VIII Session PTue: Posters-Tuesday
    Date and Time: 2/4/2014 6:00PM

    We demonstrate high amplified spontaneous emission (ASE) contrast pulses in a Nd:glass laser system based on the hybrid double chirped pulse amplification (Double CPA) scheme. By an OPA temporal cleaning device, ~100uJ/46fs/1011 clean pulses are generated and amplified in the next Nd:glass laser. After compressor, >150mJ/~0.5ps/1Hz pulses can be obtained. The ASE temporal contrast of amplified pulses is ~1011 with energy gain ~4×104 in the Nd:glass amplifiers.

    Femtosecond laser production of mixed metal oxides for efficient water oxidation
    Paper 8967-56

    Author(s):  Kasey C. Phillips, Harvard Univ. (United States), et al.
    Conference 8967: Laser Applications in Microelectronic and Optoelectronic Manufacturing (LAMOM) XIX Session PTue: Posters-Tuesday
    Date and Time: 2/4/2014 6:00PM

    We present a novel method for producing mixed metal oxides by femtosecond laser irradiation of metallic foil in the presence of oxygen and another metallic dopant. We explore the possibility of creating intermediate states in the band gap by doping with metals, such as chromium, manganese, and nickel. We present compositional data from X-ray photoelectron and Raman spectroscopy and structural data from scanning electron microscopy. Using a three-electrode setup, we present photoelectrochemical results and show enhanced water oxidation under illumination. Our research presents an innovative approach using laser scanning techniques to create new materials for visible-light watersplitting.

    Three-dimensional nano-structuring of polymer materials by controlled avalanche using femtosecond laser pulses
    Paper 8972-61

    Author(s):  Sima Rekstyte, Vilnius Univ. (Lithuania), et al.
    Conference 8972: Frontiers in Ultrafast Optics: Biomedical, Scientific, and Industrial Applications XIV Session PTue: Posters-Tuesday
    Date and Time: 2/4/2014 6:00PM

    We overview the basic principles and the most important developments of three-dimensional (3D) direct laser writing in polymers. Challenges to reach reliable structuring with sub-100 nm resolution in all three dimensions without compromise of a high speed fabrication required for practical applications are discussed. Research into the structuring by ultrashort laser pulses has seen immense growth over the last decade due to its flexibility, easy handling and wide spectrum of applications. Here a detailed discussion regarding the mechanisms of the linear and nonlinear light absorption at tight focusing conditions is given, typical laser writing conditions and numerical examples are provided. The photochemistry of traditional and novel photopolymers together with their photosensitization and sample developing strategies are presented. We show that ultra-short sub-1 ps pulses are capable to create polymerizable species by direct absorption and bond breaking at ~TW/cm2 irradiance at the focal spot. A well-controlled local heating finishes polymerization on a longer time scales > 10 - 100 ns. With thermal and linear absorption via avalanche ionization an efficient use of light energy is used for polymerization. This is a unique feature for ultra-short laser irradiation. Potential future applications are as diverse - as functional metamaterials, plasmonics, micro-optics, and microfluidic devices and cell scaffolds. Possible directions of up-scaling the fabrication throughput for industrial demands are introduced. 3D laser writing is becoming a part of wider field of additive manufacturing which is innovating number of fields in micro-machining and functional device fabrication.

    Development of high Tc superconducting coated conductors based on laser processing technologies
    Paper 8967-17

    Author(s):  Takanobu Kiss, Kyushu Univ. (Japan), et al.
    Conference 8967: Laser Applications in Microelectronic and Optoelectronic Manufacturing (LAMOM) XIX Session 9: Materials for Energy Conservation
    Date and Time: 2/5/2014 8:10AM

    We will review recent advancement in laser processing for long-length production of high Tc superconducting tapes in Japan on an industrial scale with lengths of several 100’s meters to kilometers by use of reel-to-reel high rate pulsed laser deposition (PLD) system. Columnar growth by the PLD is also suitable to introduce artificial nano-rods in the superconducting layer for further enhancement of in-field current carrying capability. Furthermore, laser slitting is essential to obtain narrow tape strands without degradation. These processing are crucial to realize high energy-efficiency electric devices such as superconducting power transmission cables and transformers.

    Fs-laser microstructuring of laser-printed LiMn2O4 electrodes for manufacturing of 3D microbatteries
    Paper 8968-5

    Author(s):  Johannes Pröll, Karlsruher Institut für Technologie (Germany), et al.
    Conference 8968: Laser-based Micro- and Nano-Processing VIII Session 1: Direct-write Processing and Surface Modification I
    Date and Time: 2/5/2014 9:30AM

    Within a new approach, laser structuring techniques have been developed for manufacturing three-dimensional cathode architectures directly into laser-printed porous lithium manganese oxide cathodes. In order to further improve the cycling behavior of laser-printed thick film cathodes at high discharging rates, cathodes were first calendered and then structured using ultrafast femtosecond laser radiation with a pulse length of 350 fs. Laser-printed, calendered, and laser-structured thick films were electrochemically tested. Therefore, cyclic voltammetric measurements and galvanostatic testing were performed. It is shown that calendered/laser-structured cathodes in the form of rectangular three-dimensional grids exhibit improved discharge capacity retention at higher discharging rates.

    3D two-photon lithography: an enabling technology for photonic wire bonding and multi-chip integration
    Paper 8970-5

    Author(s):  Christian Koos, Karlsruher Institut für Technologie (Germany), et al.
    Conference 8970: Laser 3D Manufacturing Session 2: Multi-photon Polymerization of 3D Micro- and Nanostructures I
    Date and Time: 2/5/2014 1:30PM

    Photonic wire bonding exploits three-dimensional (3D) two-photon lithography to fabricate single-mode connections between nanophotonic circuits that are located on different chips. The shape of the photonic wire bonds can be adjusted to the positions of the chips such that high-precision alignment becomes obsolete. The technique enables photonic multi-chip modules that combine the strengths of different optical integration platforms.

    Laser surface micro-texturing to enhance the frictional behavior of lubricated steel
    Paper 8968-6

    Author(s):  Antonio Ancona, CNR-IFN UOS Bari (Italy), et al.
    Conference 8968: Laser-based Micro- and Nano-Processing VIII Session 2: Direct-write Processing and Surface Modification II
    Date and Time: 2/5/2014 2:00PM

    We explore the possibility to control the tribological properties of lubricated steel surfaces by exploiting the flexibility of laser surface texturing (LST). Different LST geometries have been fabricated by fs-laser ablation, varying the diameter, depth and spacing of micro-dimples squared patterns. Their frictional performance have been characterized on a range of sliding velocities from the mixed lubrication to the hydrodynamic regime. The measured Stribeck curves data show that the depth and diameter of the microholes have a huge influence in determining the amount of friction reduction at the interface. Theoretical interpretations explaining the experimental results are also provided.

    Latest improvements in field deployable compound specific isotope analyzer based on quantum cascade lasers and hollow waveguide
    Paper 8993-69

    Author(s):  Sheng Wu, California Institute of Technology (United States), et al.
    Conference 8993: Quantum Sensing and Nanophotonic Devices XI Session 14: QCL-based Bio-sensors
    Date and Time: 2/5/2014 2:05PM

    We report on the latest improvements made on our field deployable compound specific isotope analyzer using quantum cascade lasers and hollow waveguide. The improvements include the use of true room temperature quantum cascade lasers which operate above ambient temperature, and the introduction of mode filtering and isolation optics for improved signal to noise ratio. We discuss the new applications with this new instrument, such as fast breath analysis with minimal isotope tracers.

    High-sensitivity QEPAS for environmental monitoring
    Paper 8993-72

    Author(s):  Aurore Vicet, Univ. Montpellier 2 (France), et al.
    Conference 8993: Quantum Sensing and Nanophotonic Devices XI Session 15: Environmental Sensing
    Date and Time: 2/5/2014 3:30PM

    We present developments of quartz enhanced photoacoustic spectroscopy (QEPAS) with laser diodes emitting at 2.3 and 3.3 µm. We show experiments dedicated to environmental purposes: methane and ethylene control. Two demonstrators are presented: a laboratory bench and a compact setup, where we have developed a cell including both the laser and the QTF. The detection limits and some key points of the setup are evaluated. We have developed antimonide laser to reach long wavelengths: photonic crystal based lasers inspired by coupled cavities, photonic crystal based DFB lasers and new DFB lasers. Quantum cascade lasers have been dedicated as well.

    p x n-Type transverse thermoelectrics: an alternative Peltier refrigerator with cryogenic promise
    Paper 9000-5

    Author(s):  Chuanle Zhou, Northwestern Univ. (United States), et al.
    Conference 9000: Laser Refrigeration of Solids VII Session 2: Novel Cooling Concepts
    Date and Time: 2/5/2014 3:40PM

    Band-engineered transverse thermoelectrics with p-type Seebeck in one direction and n-type orthogonal are introduced, with off-diagonal terms that drive heat flow transverse to electrical current. Such materials are named p × n (“p-cross-n”) type transverse thermoelectrics. Whereas thermoelectric performance is normally limited by the figure of merit ZT, transverse thermoelectrics can achieve arbitrarily large temperature differences in a single leg Peltier cooler even with inferior ZT by being geometrically tapered. Because the Peltier cooling mechanism is intrinsic, p × n thermoelectrics can operate at cryogenic temperatures where standard longitudinal thermoelectrics fail.

    High speed surface functionalization using direct laser interference patterning, towards 1 m²/min fabrication speed with sub-μm resolution
    Paper 8968-10

    Author(s):  Andrés F. Lasagni, Fraunhofer IWS Dresden (Germany), et al.
    Conference 8968: Laser-based Micro- and Nano-Processing VIII Session 3: Laser Nano-structuring and Processing I
    Date and Time: 2/5/2014 4:00PM

    Periodic patterned surfaces can be used to provide unique surface properties in applications, such as biomaterials, photonics and sensor systems. Such periodic patterns can be produced using laser processing tools. On the other hand, to achieve both high fabrication speed and resolution at low fabrication cost, the development of new laser structuring technologies is necessary. In this paper, different approaches for the large area fabrication of repetitive surface structures using Direct Laser Interference Patterning with sub-µm resolution and structuring speeds up to 1 m²/min will be introduced. The use of these patterned surfaces in different applications will be also described.

    Interband cascade lasers for the mid-infrared spectral region
    Paper 9002-46

    Author(s):  Sven Höfling, Julius-Maximilians-Univ. Würzburg (Germany), et al.
    Conference 9002: Novel In-Plane Semiconductor Lasers XIII Session 11: Mid-Infrared Lasers II
    Date and Time: 2/5/2014 4:00PM

    Interband cascade lasers are mid-infrared semiconductor lasers that are very promising for low power consumption applications in the 3-6 µm spectral range. Therefore, they are ideal for gas sensing of hydrocarbons. Combining interband transitions utilized in diode lasers with a cascading scheme widely exploited in intersubband transition based quantum cascade lasers, interband cacscade lasers can operate at threshold current densities around or below 100 Acm-2 at room temperature. Distributed feedback interband cascade lasers emit at room temperature continuous wave output powers in the mW range and above, and their side mode suppression ratio can well exceed 20 dB.

    Electro-luminescent cooling in the deep sub-bandgap bias regime
    Paper 9000-6

    Author(s):  Parthiban Santhanam, Massachusetts Institute of Technology (United States), et al.
    Conference 9000: Laser Refrigeration of Solids VII Session 2: Novel Cooling Concepts
    Date and Time: 2/5/2014 4:10PM

    Recent work on electro-luminescent cooling has focused either on diodes at forward bias voltages just below the bandgap energy, where high cooling power density is possible, or voltages below the thermal voltage, where the effect is more tolerant to parasitic non-radiative recombination. Here we consider the possibilities for diodes designed to operate at intermediate voltages. Numerical calculations suggest that design for this regime may enable near- and mid-infrared devices capable of solid-state refrigeration with sufficient power density for some applications.

    Laser generated microstructures in tape cast electrodes for rapid electrolyte wetting: new technical approach for cost efficient battery manufacturing
    Paper 8968-11

    Author(s):  Wilhelm Pfleging, Karlsruhe Institute of Technology (Germany), et al.
    Conference 8968: Laser-based Micro- and Nano-Processing VIII Session 3: Laser Nano-structuring and Processing I
    Date and Time: 2/5/2014 4:30PM

    A critical step in lithium-ion pouch cell manufacturing is to realize homogeneous electrolyte wetting of stacked electrodes and separators by expensive and time-consuming vacuum and storage processes at elevated temperatures. An advanced and cost efficient laser process has been developed which enables a significant improvement of electrode wetting. Preliminary investigations for testing the process on pouch cell geometry revealed higher capacities and increased cycle times compared to standard cells without storage processes at elevated temperatures. The process can be applied to commercial electrode materials and integrated into existing production lines.

    Piezoforce and contact resonance microscopy correlated with Raman spectroscopy applied to a non-linear optical material and to a lithium battery material
    Paper 8988-64

    Author(s):  Rimma Dekhter, Nanonics Imaging Ltd. (Israel), et al.
    Conference 8988: Integrated Optics: Devices, Materials, and Technologies XVIII Session PWed: Posters-Wednesday
    Date and Time: 2/5/2014 6:00PM

    A non-linear optical material (KTP) and a lithium-ion conductive glass ceramic (LICGC) for lithium batteries have been studied with Raman Spectroscopy on-line with Piezo Force and Contact Resonance Microscopies. This is allowed by a unique design of the scanned probe microscopy platform used in these studies and the electrical probes that have been developed that keep the optical axis completely free from above so that such combinations are feasible. The integration allows the investigation of alterations in the strain induced in the chemical structure of the materials as a result of the induction of piezo force. The combination of chemical characterization with both piezo force and contact resonance [1] microscopy allows for the monitoring of structural and ionic changes using Raman scattering correlated with these modalities. In KTP, it has been seen that the largest changes take place in TiO6 octahedral structure symmetric and antisymmetric stretch in the interfaces between the regions of the poling of the structure. In the LICGC, defined Raman changes are observed that are related to the contact resonance frequency. The combination adds considerable insight into both the techniques of Piezo Force Microscopy and Contact Resonance Microscopy.

    High absorption and polarization-independent thin-film absorber with gold nanorod array
    Paper 8994-75

    Author(s):  Guangyao Su, Peking Univ. Shenzhen Graduate School (China), et al.
    Conference 8994: Photonic and Phononic Properties of Engineered Nanostructures IV Session PWed: Posters-Wednesday
    Date and Time: 2/5/2014 6:00PM

    Thin film absorber with nanorod array is numerical studied in this paper. The absorption property is largely impacted by the lattice period in x direction (W1) and in y direction (W2) but less by another nanorod in y direction. Base on it, multi-band and polarization insensitive thin film absorber is designed. Nanorods with different lengths in adjacent lattices are arranged periodically both in x direction and y direction. Simulation results show that both the two ways are feasible. The optimized structure achieves three absorption peaks over 90% between 1.4 um to 2.2 um under normal incident plane wave with E field parallels to x polarization and y polarization.

    Cutting and drilling of carbon fiber reinforced plastics (CFRP) by 70W short pulse nanosecond laser
    Paper 8963-27

    Author(s):  Peter Jaeschke, Laser Zentrum Hannover e.V. (Germany), et al.
    Conference 8963: High-Power Laser Materials Processing: Lasers, Beam Delivery, Diagnostics, and Applications III Session 7: Laser Cutting I
    Date and Time: 2/6/2014 8:40AM

    We investigated cutting and drilling of carbon fiber reinforced plastics (CFRP) based on a thermoset matrix with a short pulse nanosecond laser (max. 7mJ @ 10 kHz, 30 ns) in a large parameter range. This laser offers the opportunity of wide range parameter tuning for systematic process optimization. By applying drilling and cutting operations based on galvanometer scanning techniques in single- and multi-cycle mode, excellent surface and edge characteristics in terms of intact fiber-matrix adhesion were achieved. The results indicate that nanosecond disk laser machining could consequently be a suitable tool for the automotive and aircraft industry for CFRP machining.

    Wide band gap semiconductors for optical refrigeration: an overlook
    Paper 9000-13

    Author(s):  Jacob B. Khurgin, Johns Hopkins Univ. (United States), et al.
    Conference 9000: Laser Refrigeration of Solids VII Session 3: Laser Cooling in Semiconductors
    Date and Time: 2/6/2014 9:20AM

    While laser refrigeration of solids doped with rare earth atoms has seen significant successes, the experiments performed with semiconductors have not achieved net cooling until recent experiments with CdSe nano ribbons. This points out to the wide bandgap semiconductors, such as nitrides and II-VI compounds as a possible solution. Wide bandgap semiconductors are characterized by low Auger recombination, large phonon energy, and strong electron-phonon coupling – all highly desirable features for laser cooling. In this talk we shall perform the assessment of different wide bandgap materials and identify the optimum strategy for efficient cooling of semiconductors.

    Laser-printed/structured thick-film electrodes for Li-ion microbatteries
    Paper 8968-21

    Author(s):  Heungsoo Kim, U.S. Naval Research Lab. (United States), et al.
    Conference 8968: Laser-based Micro- and Nano-Processing VIII Session 5: Batteries and Thin Film Structuring
    Date and Time: 2/6/2014 10:40AM

    There is an increasing demand for rechargeable micropower sources for the development of microelectronic devices. Thin film Li-ion microbatteries are being studied as a potential micropower source due to their high power density and long cycle life. However, the thickness of these thin film systems (normally prepared by sputtering techniques) is limited to a few microns (< 5 μm) due to high internal resistance of the dense electrodes. One way to achieve high discharge capacity per active electrode area is to develop thick-film electrodes deposited by laser induced forward transfer (LIFT). In this work, various thick-film electrodes (up to ~115 um) are laser-printed onto metallic current collectors and assembled into functional Li-ion microbatteries. Microbatteries based on these thick-film electrodes demonstrate significantly higher discharge capacities than those made by sputter-deposited thin film techniques. This increased performance is attributed to the porous structure of the laser-printed electrodes that allows improved diffusion of the Li-ions without a significant increase in internal resistance. The packaged microbatteries exhibited discharge capacities in excess of 2500 μAh/cm2 at a constant charge/discharge rate of 100 μA/cm2. In this talk, we will present details on the fabrication of Li-ion microbatteries with various cathodes and anodes in terms of electrode thickness, discharge capacity, charge/discharge rate, and cycling performance. In addition, we will also present the use of an ultrafast laser ablation process to prepare three-dimensional grid microstructures to further improve performance by increasing the active surface area in the laser-printed and then laser-structured thick-film electrodes.

    Ultrafast laser microstructuring of LiFePO4 cathode material
    Paper 8968-22

    Author(s):  Melanie Mangang, Karlsruher Institut für Technologie (Germany), et al.
    Conference 8968: Laser-based Micro- and Nano-Processing VIII Session 5: Batteries and Thin Film Structuring
    Date and Time: 2/6/2014 11:10AM

    LiFePO4 is a very promising material to be used as positive electrodes for future lithium-ion cells. Nevertheless, a reduced rate capability at high charging-/discharging currents is in general a main drawback. In this work, a 3D topography was realised in the surface of a LiFePO4 cathode by applying different pulse length (ns to fs). With ultrashort laser radiation it was possible to obtain defined structures in the electrode surface without thermal damage. It was shown that the rate capability was significantly enhanced, especially for high charging-/discharging rates. Up-scaling to pouch cell format (5x5cm²) was realised for structuring with 350fs.

    Next generation optical refrigerators
    Paper 9000-18

    Author(s):  Richard I. Epstein, The Univ. of New Mexico (United States), et al.
    Conference 9000: Laser Refrigeration of Solids VII Session 5: Applications and Device Concepts
    Date and Time: 2/6/2014 1:20PM

    Advances over the last few years has made optical refrigeration the first solid-state technology that can cool from room temperatures to cryogenic temperatures. At the current operation temperatures of near 100K, this technology can cool conventional electronics, gamma ray spectrometers and cryocoolers that go to much lower temperatures. The next-generation optical refrigerators will operate below 70 K with coefficients of performance above 10. These optical refrigerators would be more compact and efficient than mechanical cryocoolers and produce no vibrations. Achieving these goals requires new high-performance cooling materials and high-efficiency lasers and designing optical refrigerators that recycle the fluorescence.

    All-optical photon-waste recycling in laser cooling of solids
    Paper 9000-19

    Author(s):  Mansoor Sheik-Bahae, The Univ. of New Mexico (United States), et al.
    Conference 9000: Laser Refrigeration of Solids VII Session 5: Applications and Device Concepts
    Date and Time: 2/6/2014 1:50PM

    It has been shown that luminescence recycling using photovoltaic power convertors could drastically enhance the wall-plug efficiency in optical refrigeration. Analysis and methods for achieving this in an all-optical manner (i.e. without photovoltaics) will be presented here. The cooling chamber essentially consists of a thermally-isolated two-body system: an anti-Stokes upconversion material (cold side) and a Stokes down-convertor (hot side).

    Development of laser cladding system with process monitoring by x-ray imaging
    Paper 8963-35

    Author(s):  Takaya Terada, Japan Atomic Energy Agency (Japan), et al.
    Conference 8963: High-Power Laser Materials Processing: Lasers, Beam Delivery, Diagnostics, and Applications III Session 9: Laser Additive Manufacturing of Metal Structures: Joint Session with Conferences 8963 and 8970
    Date and Time: 2/6/2014 2:20PM

    We developed a laser cladding system in 1-inch tube with a composite-type optical fiberscope which has a laser delivery fiber and image delivery fibers. By X-ray imaging with Spring-8 synchrotron radiation, we found that a molten droplet was formed at the edge of a wire. Here we measured the thermo-electromotive force voltage between a wire and a tube metal to confirm whether both came in contact. The QCW laser cladding with our system was performed and we succeeded to make a line clad layer on a 1-inch tube inner wall. We are proposing to apply our technologies to plant maintenance.

    Current spreading in shallow-ridge Ion-implanted quantum cascade lasers
    Paper 9002-63

    Author(s):  Loan T. Le, Princeton Univ. (United States), et al.
    Conference 9002: Novel In-Plane Semiconductor Lasers XIII Session 14: Mid-Infrared QCLs III
    Date and Time: 2/6/2014 3:00PM

    Quantum Cascade (QC) lasers are customarily fabricated as deep-etched ridges, exposing the active region sidewalls to increased optical and thermal losses. Shallow-ridge or ridgeless geometries, while solving some of these issues, contend with potentially excessive lateral current spreading. QC lasers with the shallow-ridge ion-implanted geometry are attractive because of the minimal current spreading that can be achieved without the optical and thermal losses incurred by deep etching. Here, we conduct comprehensive experimental and modeling work to quantitatively attribute current spreading to the actual device geometry with the goal of optimizing the device geometry.

    Study of a-Si crystallization dependence on power and irradiation time using a cw green laser
    Paper 8968-33

    Author(s):  Miguel Morales, Univ. Politécnica de Madrid (Spain), et al.
    Conference 8968: Laser-based Micro- and Nano-Processing VIII Session 7: Photovoltaics and Energy Devices: Joint Session with Conferences 8967 and 8968
    Date and Time: 2/6/2014 5:40PM

    An advantage of laser crystallization over conventional heating methods is its ability to limit rapid heating and cooling to thin surface layers. Laser energy is used to heat the a-Si thin film to change the microstructure to poly-Si. Thin film samples of a-Si were irradiated with a cw-green laser source. Laser irradiated spots were produced by using different laser powers and irradiation times. These parameters are identified as key variables in the crystallization process. The power threshold for crystallization is reduced as the irradiation time is increased and once reached crystalline fraction increases lineally with power for each irradiation time.

    Important Dates

    Abstracts Due
    17 July 2017

    Author Notification
    25 September 2017

    Manuscripts Due
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    Journal of Photonics for Energy