Study of instability of semiconductor laser in a coupled cavity configuration

• Main Authors: Yen-De Lee, 李彥德
• Other Authors: How-Foo Chen
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/fxpq8q

碩士 === 國立陽明大學 === 生醫光電工程研究所 === 96 === Ultra-short-pulse lasers have proved their advantages on modern microscopy technologies, such as optical coherent tomography (OCT),harmonic microscopy, nonlinear Raman microscopy, and two-photonfluorescence microscopy and their variations as well. Among the lightsources, Ti-Sapphire lasers are the main trend light sources in these applications. However, the disadvantages of Ti-Sapphire lasers are itscost and bulky size, which limit the applications translated from bench to bedside. Semiconductor lasers have been recognized as highly efficient andcompact coherent light sources, which have been used in many fields,such as optical communication, recording systems, and projection display. However, due to the difficulty of implementing ultra-short-pulse semiconductor lasers, utilizing semiconductor lasers in modern microscopy technologies are still challenge and current interest. In several laser technologies to generate sub-picosecond lasers, additive pulsedmode locked laser is very attractive since such technology does not require material-dependent design and processing on semiconductor gain medium and the average power is not reduced too much under the mode-locking operation. However, because of the significant chirping parameter of semiconductor gain medium, any undesired optical feedbackcan destroy the stability of the lasers. Therefore, stability of APM-configuration on semiconductor lasers is a very important issue to successfully implement APM semiconductor lasers.In this thesis, I studied the instability of semiconductor laser in a coupled-cavity configuration first. We use a edge-emitted semiconductor laser(InGaAsP/InP, λ=1.3μm)and construct a new cavity, called〝main cavity〞, caused by two facetsanti-reflection coating (R=1~2x10-4). Then, the output power range of the main cavity is 10~11mW at a repetition rate is of 231.76MHz. Furthermore, we observed the decrease of the main cavity spectrumbandwidth and the intensity of the original laser mode increased whenmain cavity length is longer (20~60cm). Then, the external cavity was build by optical fiber with nonlinear effect. We experimentally employed a high-reflection mirror and a concave mirror individually to observe the reflection noise induced by coherent optical feedback into the main cavity. Finally, with increasing optical feedback level, the spectrum isbecome distortion. It has also been recognized that reflection back into the main cavity from a mechanically unstable mirror cause noise in the output spectrum and power.