tudy of Backward-Optical-Injection Mode-Locked Semiconductor Optical Amplifier Fiber Lasers

• Main Authors: Yu-Sheng Liao, 廖育聖
• Other Authors: Gong-Ru Lin
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/48974906650682324415

碩士 === 國立臺北科技大學 === 光電技術研究所 === 92 === In this thesis, we study the harmonic mode-locking dynamics of a backward optical injection modulated SOAFL. The effects of gain-depletion time and modulation frequency on the mode-locked pulse shape and power have also been theoretically analyzed and experimentally demonstrated. The backward sinusoidal-wave modulation is much easier to initiate harmonic mode-locking in SOAFL than the gain-switched modulation, which generates pulsewidth as short as 12 ps at 5 GHz. The difficulty in mode-locking the SOAFL by optical short pulse injection is also demonstrated and explained, which is attributed to the insufficient gain-depletion time (as well as modulation depth). The analytical results indicate that the SOAFL mode-locked by backward optical sinusoidal-wave injected SOA exhibits better mode-locking capability than that a pulsed-injected SOA when the SOA is nearly transparent. The backward optical sinusoidal-wave injection of SOA also facilitates the generation of a pedestal-free mode-locked pulse from SOAFL. To further analyze the build-up dynamics of the mode-locked SOAFL with different gain-depletion times, the SOA is injected using a TTL-encoded DFBLD with various duty cycles. The minimum gain-depletion time is determined to be 250 ps for starting the mode-locking in the backward optical injected SOAFL. Finally, the optimized gain-depletion time required for mode-locking the SOAFL is observed to be between 400 and 600 ps.