Double-asymmetric-structure 1.5 μ m high power laser diodes

Abstract Design considerations for high pulsed power and brightness 1.5 μm laser emitters for laser radar applications, based on comprehensive semi-analytical theory, are presented. A strongly asymmetric waveguide design with a bulk active layer positioned very near the p-emitter interface is chosen to minimize the current-induced losses at high power while maintaining a single, broad transverse mode. Moderate to high doping of the n-side of the Optical Confinement Layer and high p-doping of the p-cladding layer are used to reduce the residual current-induced losses and the electric resistance of the structure. For pulsed room-temperature operation, short laser resonators are found to be advantageous. First experimental results are presented. An as-cleaved sample with a stripe width of 90 μm and a resonator 2 mm long exhibits an output power of about 18 W at a pumping current amplitude of 80 A, with 1 mm long resonators showing higher power output. Further improvements are predicted by structure optimization as well as increase in internal quantum efficiency and thermal performance

High power 1.5 μm pulsed laser diode with asymmetric waveguide and active layer near p-cladding

Abstract We report first experimental results on a high-power pulsed semiconductor laser operating in the eye-safe spectral range (wavelength around 1.5 μm) with an asymmetric waveguide structure. The laser has a bulk active layer positioned very close to the p-cladding in order to eliminate current-induced nonuniform carrier accumulation in the p-side of the waveguide and the associated carrier losses. Moderate doping of the n-side of the waveguide is used to strongly suppress nonuniform carrier accumulation within this part of the waveguide. Highly p-doped InP p-cladding facilitates low series resistance. An as-cleaved sample with a stripe width of 90 μm exhibits an output power of about 18 W at a pumping current amplitude of 80 A. Theoretical calculations, validated by comparison to experiment, suggest that the performance of lasers of this type can be improved further by optimization of the waveguide thickness and doping as well as improvement of injection efficiency

High-power 1.5μm laser diodes for LIDAR applications

Abstract We report on the development of high peak power laser diodes emitting in the 1.5μm wavelength band for eye-safe LIDAR applications. Different techniques for wavelength locking to and operation with a narrow emission spectrum are discussed. Furthermore, we review the strategies to increase the beam brightness. Recent progress in new epitaxial layer designs enabling high peak powers is also discussed. Finally, we discuss the performance of the laser diodes in terms of improvements they render possible for high-performance LIDAR systems