Edge emitting laser diodes are well known and used in a vast portfolio of applications. High power pulsed edge-emitting laser diodes in the 905 nm regime have proven to be robust and reliable under operating conditions that require low repetition rates and pulse widths longer than several tens of nanoseconds. Automotive LiDAR requires other typical operating conditions: high repetition rates and short pulse widths at or below 5 ns. Therefore, a suitable reliability model that take into account these unique operating conditions is required. This work will present a universal reliability model focusing on the impact of short pulse widths on the lifetime reliability of GaAs-based high power edge emitting lasers. In order to set an empirical model, a dedicated experimental setup was conducted in-house. Pulse widths as short as 1.5 ns were used in combination with 100 kHz frequency in order to carry out accelerated tests. Proper life tests of more than 1000 hours were conducted in order to gain an insight on the impact of the pulse width on the overall reliability. Influence of the pulse width from 1.5 ns to 200 ns on the mean time to failure of typical lasers will be detailed herein. One of the main validated predictions of the new lifetime model is that use of long pulse widths allows high acceleration factors for a constant duty cycle without damaging the optical cavities for the automotive LiDAR market.
Ivoil Koutzarov, Harry Ruda, Chandima Edirisinghe, Lech Jedral, Qiang Liu, Alan Moore, Richard Henderson, Marcel Boudreau, Mohamed Boumerzoug, Peter Mascher
We report on passivation of AlxGa1-xAs/GaAs surfaces using different sulfur and chlorine based treatments: These include ammonium sulfide solution, arsenic sulfide vapor and hydrochloric acid treatments. Enhancements in the intensity of near band-gap photoluminescence (PL) peaks, coupled with peak half-width reduction on treatment were attributed to a reduction in the density of surface states. Pre-etching using sulfuric acid- and ammonium hydroxide-based solutions prior to sulfur passivation was also found to contribute significantly to the overall success of a passivation treatment. The best sulfur-passivation results for all x (0 < x < 0.38) were found when sulfuric acid-peroxide-deionized water (Caros) solution pre-etching was followed by ammonium sulfide solution treatment at 65 degree(s)C for 25 min.
We describe the design, growth by atmospheric pressure metalorganic chemical vapor deposition (MOCVD), processing and characterization of single quantum well separate confinement strained layer InGaAs-GaAs quantum well lasers designed for high power operation at emission wavelengths near 1064 nm. Threshold current density is reduced by 39% for long cavity devices through design optimization. Broad area lasers operate at high cw (> 5 W) and pulsed (> 20 W) powers, with low threshold current density and high power conversion efficiency. Index guided ridge waveguide lasers show stable single spatial mode operation over a wide range of output power and temperature.
Laser diodes and superluminescent diodes have been fabricated using epitaxial structures employing a strained quantum well of InAlGaAs. These devices emit at wavelengths in the 800 - 900 nm range commonly addressed using unstrained GaAs quantum well structures. Results are presented which indicate that the strained layer devices exhibit a marked immunity from sudden unexpected ('freak') failure modes.
We describe 2.5Mm wide Ridge Waveguide Lasers emitting in the wavelength range 1045nm-1065nm. These are fabricated from strained layer single quantum well epitaxial heterostructures with 30%-31% InAs in the quantum well. The devices exhibit stable single spatial mode, single spectral line operation over a wide range of output power and temperature. Preliminary data suggests that reliable high power CW operation may be obtained.
We describe 2?m wide ridge waveguide lasers emitting at a wavelength of 980nm using a strained single quantum well epitaxial structure. These devices exhibit high coupling efficiency into single mode fiber. We have coupled up to 60mW using an industry standard 14-in dual-in-line package. Such devices are ideal for pumping Er-doped Fiber Amplifiers.
The high power and broad spectral output of superluminescent diodes (SLDs) are desirable for fiber optic gyroscopes, optical sensors and short to medium haul communications. Certain applications are sensitive to spectral modulation on the subnanometer wavelength scale where coherent interference can be a source of noise. We present a simple SLD design which eliminates the optical feedback within the chip normally responsible for spectral modulation. Although the design can be applied to conventional SLD wavelengths, initial device demonstration at 960 nm has been chosen to illustrate SLD operation in a materials system in which spectral modulation is particularly difficult to suppress. Ridge waveguide based SLDs suitable for coupling to single mode fiber have been fabricated. Typical output is 10 mW cw at 140 mA with a spectral width of 30 nm and less than 5% spectral modulation over a wide range of operating conditions.
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