高功率单模GaAlAs/GaAs激光器

HIGH POWER SINGLE MODE GaAlAs/GaAs LASER

本文报告了隐埋双脊衬底大光腔结构GaAlAs/GaAs激光器的制备和特性,获得CW光输出的最高功率可达80mW。

In this paper, we report the manufacture and characteristics of buried twin-ridge substrate large optical cavity structure GaAIAs/GaAs laser (BTRS-LOC). This laser has following features.(1) Thethinner active layer(~0.1μm) can be grown by Using LPE on the twin-ridge substrate. The optical power confinement factor will become smaller, so the large spot size of near-field pattern at facets can be obtained. (2) The spot size of the near-field pattern is further enlarged by the LOC structure. (3) The current confinement to the stripe is realized by a reverse-biased heterojunction of n-GaAs (current blocking layer) and p-GaAlAs (first cladding layer). (4) The transverse mode is confined by the built-in refractive index difference which is caused by the fact that outside the channeled region, the evanescent tails of lasing light reach the current blocking layer. Because the current blocking layer is obsorptive and has higher refractive index than the layers in the channel. It is possible to control the built-in refractive index difference by varying the shape of evanescent tails on the side of the current blocking layer.This device was made by two times of LPE growth. Prior to the LPE growth, a rectangular mesa with 3μm height and 20μm width was formed along a direction of [011] on a (100) surface of the p-GaAs substrate for the first LPE growth. A 5um width channel was etched parallel to the mesa. The channel was located in the center of the mesa and reached to the p-GaAs substrate. Five layers,p-Ga0.62Al0.38As (first cladding layer), the p-Ga0.85Al0.15 As waveguide layer, the n-GaAs active layer, the N-Ga0.62Al0.38 As (second cladding layer), and the n-GaAs contact layer were successively grown for second LPE growth. The thickness of the active layer was successfully controlled to be in a range of 0.1μm.The BTRS-LOC lasers show a range of CW threshold current of 30-100 mA. The linear power output can be remained upto 65 mW and the highest power output of 80mW is also obtained. A external differential quantum efficiency of 34% (per facet) is achieved and the highest peak power output of 300 mW is obtained under low duty cycle (500 ns pulse width and 5.6-kHz repetition rate) pulse condition. A narrow far-field angle of 8.50×23 (full width at half-maximum) is achieved.