Photonics Research, 2018, 6 (10): 10000C29, Published Online: Sep. 6, 2018
212-kHz-linewidth, transform-limited pulses from a single-frequency Q-switched fiber laser based on a few-layer Bi2Se3 saturable absorber
Abstract
Conventional Q -switched fiber lasers operating at multi-longitudinal-mode oscillation usually suffer from self-mode-locking-induced temporal instability, relatively strong noise, and low coherence. Here, we address the challenge through demonstrating, for the first time, to the best of our knowledge, a single-longitudinal-mode (SLM) Er-doped fiber (EDF) laser passively Q -switched by a few-layer Bi 2 Se 3 saturable absorber (SA). The Bi 2 Se 3 SA prepared by the liquid-phase exfoliation method shows a modulation depth of ~ 5 % and saturation optical intensity of 1.8 MW / cm 2 . A section of 1-m unpumped EDF together with a 0.06-nm-bandwidth fiber Bragg grating is used as an ultra-narrow autotracking filter to realize SLM oscillation. Stable SLM Q -switching operation at 1.55 μm is successfully achieved with the spectral linewidth as narrow as 212 kHz and the pulse duration of 2.54 μs, manifesting near-transform-limited pulses with a time-bandwidth product of 0.53. In particular, we found that the SLM Q -switching possesses the higher signal-to-noise ratios of 62 dB (optical) and 48 dB (radio frequency), exhibiting its advantages of low noise and high stability. Such an SLM Q -switched fiber laser could gain great interest for some applications in coherent detection, coherent optical communications, and high-sensitivity optical sensing.
Weiwei Li, Jinhai Zou, Yizhong Huang, Kaijie Wang, Tuanjie Du, Shuisen Jiang, Zhengqian Luo. 212-kHz-linewidth, transform-limited pulses from a single-frequency Q-switched fiber laser based on a few-layer Bi2Se3 saturable absorber[J]. Photonics Research, 2018, 6(10): 10000C29.