Temperature controllable optical switch for erbium-doped random fiber laser

作者：Wu, Di; Tian, Shuang; Zhang, Xiaojuan; Yu, Benli; Ma, Jiajun; Xie, Kang; Cheng, Sheng; Zhang, Junxi^*; Hu, Zhijia^*

来源：Optics and Laser Technology, 2022, 148: 107772.

DOI：10.1016/j.optlastec.2021.107772

• Erbium-doped fiber
• Random fiber laser
• Photonic crystal fiber
• Liquid crystal

Different from the conventional optical switches, a rapid response and simple structure of erbium-doped random fiber laser for optical switch is presented. The random fiber laser (RFL) was achieved by pumping an erbium-doped fiber connected with tens of kilometers of single-mode-fiber (SMF). Meanwhile, the 1 cm-long photonic crystal fiber (PCF) filled with a liquid crystal (LC), which is spliced after the reflected output port of a 980/1550 nm wavelength division multiplexing (WDM) coupler, is used as the sensing unit. A high-extinction ratio more than 36 dB over a wavelength range from 1529.00 nm to 1533.16 nm can be observed when the temperature increases from 60 degrees C to 61 degrees C. The high-extinction ratio RFL is caused by the reduction of refractive index of the LC-filled PCF (LCPCF). Under the action of the band gap guiding mechanism, the LC molecules in PCF change from each anisotropic to each isotropic when the temperature increases from 60 degrees C to 61 degrees C, which induces thermo-optical switch of the LCPCF. The optical switch of erbium-doped fiber random fiber laser has the best comprehensive performance with low cost, high sensitivity, strong anti-electromagnetic interference ability based on control of the temperature.