Workshop on Optical Feedback and Facet Stability in High Power Semiconductor Lasers

Sunday, 16 September 2018

Chairs: P. Leisher, LLNL CA USA; P. Crump, FBH Berlin Germany


The expanding application space of high power diodes lasers requires continuous improvement in both performance and robustness.  Optical feedback to the semiconductor laser is one of the most critical aspects affecting both performance and reliability.  When carefully applied, intentional optical feedback is a powerful tool for optimizing output power and efficiency, stabilizing and narrowing the emission spectrum, and controlling the spatial mode profile.  For example, external optical feedback provided by holographically-defined volumetric Bragg gratings enables wavelength stabilization with negligible impact on device power and efficiency, enabling low quantum defect resonant pumping of rare-earth laser gain media.  Power scaling of diode lasers by means of extremely large optical cavities and long resonator lengths relies on careful control of the facet coating properties to enable efficient lasing in the fundamental transverse mode.  Uncontrolled or unintentional optical feedback can also be highly detrimental to the performance and robustness (lifetime) of diode lasers, and can easily arise in complex systems where the output of many diode lasers is optically combined, such as in high brightness fiber laser pumps or direct diode material processing systems.  Several issues arising from feedback include intensification of beam filamentation, destabilization of the lasing spectrum, increased noise, lower beam quality, and reduced lifetime.  For example, parasitic back-reflections and emission from pumped laser gain media can greatly accelerate catastrophic optical mirror damage. Increasing our understanding of the effects of optical feedback is vital to improving the performance of high power diode lasers, as is increasing the ability of the devices to resist the negative impact of uncontrolled feedback (e.g. increased facet robustness).  In particular, techniques to exploit and simplify the beneficial effects of optical feedback while mitigating or eliminating the detrimental effects must be developed.  This workshop of invited speakers will discuss ongoing work by various groups in this area.  The workshop forum is meant to stimulate discussions and interaction with the audience.


Heiko Kissel, DILAS Diodenlaser GmbH, Germany, “Accelerated Degradation of High Power Diode Lasers Caused by External Optical Feedback Operation”

Andreas Kohl & Steve Patterson, Quantel, MT, USA, “Pulsed High Power Diode Arrays for Pumping and Direct Illumination”

Stewart McDougall, TRUMPF Photonics, Inc., NJ, USA, “Advanced Laser Bar Development for High Brightness Direct Diode Sources”

Jerry Moloney, Arizona Center for Mathematical Sciences, University of Arizona, AZ, USA, “High Brightness, Low Noise CW and GHz Repetition Rate Mode-Locked Semiconductor Disk Lasers”

Kevin Pipe, University of Michigan, MI, USA, “Thermoreflectance Imaging of High Power Diode Lasers Under Back-irradiance Conditions”

Mindaugas Radziunas, Weierstrass Institute for Applied Analysis and Stochastics, Germany, “Modeling and Simulation of High-power Broad-area Semiconductor Lasers with Optical Feedback From Different External Cavities”

Yagi Tetsuya, Mitsubishi Electric, Japan, “Recent Progress of High Power Broad Area Red Laser Diodes for Display Application”

Jens Tomm, Max-Born-Institut fuer Nichtlineare Optik und Kurzzeitspektroskopie, Germany, “Facet Stability of High Power GaN-based Diode Lasers”

Workshop on Stable single frequency and frequency comb lasers

Sunday, 16 September 2018

Chair: E. Bente, Technische Universiteit Eindhoven, The Netherlands


Requirements for stability and linewidth of semiconductor lasers for applications are varied but overall are becoming more demanding. E.g. telecommunication applications with advanced phase encoding require good phase stability on a short time scale. Metrology applications or fibre sensing require longer time scale stability and worry less about the high frequency noise components. Dual comb spectroscopy requires a good relative short term stability and a different long term stability. Microwave photonics applications require the highest possible stability and linewidth. A range of solutions are being used to achieve the requirements: driving lasers with optimized electronics and feedback systems; extending the laser cavity in free space optics using vertical cavities or planar amplifier structures, or using integrated optics planar waveguides where the passive optical components; using semiconductor gain media that are inherently less noisy. Many of the laser output requirements have been solved using (semiconductor laser pumped) solid-state laser systems. Where and how can semiconductor based laser systems compete?


Prince Anandarajah, Dublin City University, Pilot Photonics, Ireland, “Optimum Optical Frequency Combs for Telecommunications And Data Centre Networks”

Klaus Boller, University of Twente, Netherlands, “Extended-Cavity Single-Frequency Semiconductor Lasers Using Ring Filters in Low-Loss Silicon Nitride Technology”

David Burghoff, University of Notre Dame, IN, USA, “Terahertz Quantum Cascade Laser Frequency Combs”

Michael Davenport, University of California, Santa Barbara, CA, USA, ” Integrated Heterogeneous Silicon/Iii-V Mode-Locked Laser Based Frequency Combs”

Tomohiro Kita, Tohoku University, Japan, “Two-Wavelength Tunable Laser Diode Using a Quantum Dot Soa and a Silicon Photonic External Cavity”

Jiaren Liu, National Research Council of Canada, Canada, “InAs/InP Quantum Dot Lasers and Applications”

Lute Maleki, GM/Cruise, CA, USA, “Semiconductor Laser Stabilization with WGM Resonators”

Andreas Wicht, Ferdinand-Braun-Institut, Germany, ” Narrow Linewidth Semiconductor Laser Systems for Cold Atom-based Technology Applications”