可调谐单纵模光纤激光器模式特性研究

Investigation on the mode characteristics of single longitudinal-mode wavelength-tunable ring fiber laser

为了实现光纤激光的单纵模,提出了一种环形腔结构,采用可调谐光纤Bragg光栅(FBG)作为波长选择器件,与2m未抽运掺Er光纤(EDF)产生驻波饱和效应,在1.55μm波长处形成42nm激光输出,输出功率大于3.5dBm,功率稳定性优于±0.005dB。扫描Fabry-Porot(F-P)干涉仪观测到2个正交的偏振模,在环形腔内加入偏振器后可抑制强度较低的偏振模式,测量到清晰的单纵模激光,纵模线宽为20MHz。由于饱和吸收效应,导致了激光输出斜率曲线表现出光学双稳态现象。

To realize single longitudinal-mode of the fiber laser, a ring configuration is devised. The single longitudinal-mode operation is realized by using a fiber Bragg grating（FBG） as wavdength-selective element and a unpumped 2m-long erbiumdoped fiber（El）F） which can produce stading-wave saturation effects in the cavity. Its tunable wavelength range is 42 nm, the output power is more than 3.5 dBm and the stability is less than ±0. 005 dB. Two orthogonal polarization modes are found by using a scanning Fabry-Perot（F-P） interferometer. Then,the single longitudinal-mode is observed with a polarimeter in the cavity. The longitudinal-mode linewidth of 20 MHz is measured. The slope curve of the laser output represents optical bistability phenomena because of saturation absorption effects.