基于拉曼光谱技术的光栅耦合结构半导体激光器的可靠性分析

摘要

光栅耦合结构的半导体激光器在自由空间光通信、卫星间通信、激光雷达测距、大气环境检测以及医学成像等领域有着广泛的应用前景。为了分析光栅耦合结构的半导体激光器的可靠性，本文基于拉曼光谱技术，对光栅耦合结构的半导体激光器在不同的制备阶段及其成品进行了检测。我们发现，对于未进行任何工艺加工的半导体激光器芯片，GaAs 纵向（LO）光学光子模式的振动强而横向（TO）光学光子模式的振动弱；当在 GaAs 芯片表面生长一层 SiO2膜后，LO 模式向长波数方向移动，强度没有变化。当在生长 SiO2膜的 GaAs 芯片上刻蚀100μm 的台面后，GaAs 的 LO 模式的振动减弱而 TO 模式的振动加强，且峰出现宽化现象；在100μm 的台面上刻蚀光栅后，GaAs 的 LO 模式的振动继续减弱而 TO 模式的变得更强，这说明在光栅耦合激光器的制备工艺过程中引入了缺陷。通过与无光栅的半导体激光器进行对比测试，光栅耦合结构半导体激光器无论出光面上有无缺陷，其拉曼光谱均有缺陷峰存在，进一步证明了在光栅结构的制备过程中，引入了应变或者缺陷，对其可靠性产生了影响，导致光栅耦合结构的半导体激光器可靠性降低。%Grating coupled semiconductor lasers (GCSLs) has a wide application prospect in many fields ,such as optical free space communication ,intersatellite communication ,ranging for laser radar ,atmospheric environmental testing and medical ima‐ging .In order to verify the reliability of GCSLs ,the chips in different preparation stages and products of GCSLs are tested based on Raman spectroscopy .It concluded that for unprocessed semiconductor laser chip ,the longitudinal optical (LO) photons mode vibration of GaAs chip is strong but the transverse (TO) optical photons mode vibration of GaAs chip is weak .when the is un‐processed .When the surface of GaAs chip is covered by a layer of SiO 2 membrane ,the LO mode will movetowards long wave‐length direction ,but its intensity wouldn’t change .When a 100 m mesa is etched on GaAs chip which is covered by SiO 2 mem‐brane ,LO mode vibration of GaAs chip weakens and TO mode vibration of GaAs chip enhances ,and the peak width of LO mode and TO mode increase .After gratings are etched on the 100 m mesa ,LO mode vibration of GaAs chip continues to weaken ,but TO mode vibration of GaAs chip becomes stronger .It shows that lattice defects exist in the fabrication process of GCSLs .By contrast testson the semiconductor lasers without gratings ,it shows that defect peaks present in the Raman spectrum of GCSLs regardless of the defects on light emitting surface .This further proved that the strains or defects were introduced into the fabri‐cation process of grating structure ,which affects its reliability ,resulting in a decrease of the reliability of GCSLs .