A Study on Characteristics of Semiconductor Lasers

• Main Authors: Ken-Chao Chen, 陳耕兆
• Other Authors: 林清富
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/18055995053641156331

碩士 === 國立臺灣大學 === 光電工程學研究所 === 89 === Two main topics are investigated in this thesis. First is the study on hysteresis in nonidentical multiple quantum well GaAs lasers. Second is the study of the characteristics of InP monolithically integrated flared amplifier master oscillator power amplifier ( MFA-MOPA ). In the first topic, the relationship between hysteresis in GaAs laser amplifier and lasing wavelength is studied with a triangular ring cavity which provides tunability. The cavity is operated in the lasing range from 801.5 to 840 nm and is driven by triangular pulse current source. The L-I curve is obtained by properly matching current and power temporal waveform. The measurement is properly calibrated so that if the measured device is not a bistable one, the L-I curve will not show hysteresis. Hysteresis was observed at 801.5 nm. In the second topic, 1.55 μm high power single frequency laser is implemented by InP MFA-MOPA. Standard processing steps are applied for the fabrication. In the laser structure, spoiling grooves are added to replace the function of AR coating on both cleaved facets. The MFA-MOPAs show the maximum power 94 mW. However, the multimode spectrum and nondiffraction-limited far field do not fit the expectation. The reasons are due to the remarkable current heating effect in MO and that both cleaved facets of MOPA are not AR-coated. The reasons are discovered by individual characterization of MO ( master oscillator ) and PA ( power amplifier ). According to the individual results of MO and PA, MFA-MOPAs with both single spectral peak and high power are feasible. In the process of MO-PA separation and inspection in parts, low temperature requirement of MO measurement is achieved by a cooling system. The cooling system includes homemade -10℃ cooling stage and moisture purge chamber. By this system, the semiconductor laser is stably operated at -10℃. The versatile applications of the cooling system are expected.