All-optical frequency and intensity noise suppression of single-frequency fiber laser

• Published in: Optics letters 2015-05, Vol.40 (9), p.1964-1967
• Main Authors: Li, Can, Xu, Shanhui, Huang, Xiang, Xiao, Yu, Feng, Zhouming, Yang, Changsheng, Zhou, Kaijun, Lin, Wei, Gan, Jiulin, Yang, Zhongmin
• Format: Article
• Language: English
• Subjects: Fiber lasers; Frequency ranges; Lidar; Noise; Noise intensity; Noise levels; Noise reduction; Semiconductor optical amplifiers
• ISSN: 0146-9592; 1539-4794
• DOI: 10.1364/OL.40.001964

An all-optical frequency and intensity noise suppression technique of a single-frequency fiber laser is demonstrated. By exploiting the recursive noise reduction effect of a semiconductor optical amplifier (SOA) in a self-injection locked fiber laser, the frequency and intensity noise of the laser are remarkably suppressed in a significantly wide frequency range. In addition to the linewidth suppression from 3.5 kHz to 700 Hz, the frequency noise has been reduced by ∼25  dB. After suppression, the relative intensity noise (RIN) is within 5 dB of the shot noise limit at frequencies from 1.5 to 3 MHz, and the frequency range of the suppression reaches about 30 MHz. The relaxation oscillation peak is observed to shift to lower frequencies and is reduced by about 35 dB from -90  dB/Hz to -125  dB/Hz. It is believed that the achieved low noise makes the fiber laser a promising candidate in applications such as ultra-long haul coherent optical communication and LIDAR.