Review of Al-free active region laser diodes on GaAs for pumping applications

Abstract

Laser diodes emitting at different wavelengths can address various applications. 852nm or 894nm single frequency low linewidth laser diodes are needed for Cs pumping for realization of atomic clocks. 780nm high power low linewidth laser diodes and amplifiers are needed for Rb pumping for realization of cooled atoms based inertial sensors. High power lasers at 793nm and 975nm with wavelength stabilization are required to pump Tm and Yb doped fibres respectively. We have developed the building blocks and have realize the different kinds of laser diodes needed for various pumping applications. One of these key building blocks are the Al free active region laser structures, which allow epitaxial regrowth on a Bragg grating necessary to get single frequency or wavelength stabilized lasers.

High-Power 810-nm Passively Mode-Locked Laser Diode With Al-Free Active Region

“…Claddings are made of AlGaInP. A 0.2 μm GaAs highly doped p contact is grown at the top of the structure (figure 1) [17].…”

“…We report here a novel structure with a similar vertical mode size but also based on an Al-free active region that offers an attractive alternative to the conventional AlGaAs quantum-well design, avoiding the creation of oxide on the mirror facets. Devices based on this approach should allow better reliability and longer life time as well as more powerful emission [17].…”

Feasibility study for Al-free 808 nm lasers with asymmetric barriers suppressing waveguide recombination

“…Aluminum-free GaInAsP/GaAs heterostructures 9 emerged in the beginning of the 1990s as a promising substitute for AlGaAs/GaAs heterostructures that were commonly used at that time for near-infrared lasers. The use of GaInAsP-based material systems was primarily motivated by the following drawbacks inherent in Al-containing lasers as compared to Al-free ones: increased surface-recombination velocity 10 and electrical resistance, 11 reduced threshold of COMD, 12 as well as reduced resistance to oxidation 13 and dark-line defect formation. 14 Although the quality of facet mirror passivation was greatly improved and AlGaAs-based diode lasers later proved their reliability, Al-free laser heterostructures still remain an alternative solution for high-power diode lasers (see, e.g., Refs.…”