Switchable And Tunable Multiwavelength Random Fiber Laser Based On Rayleigh Scattering

Random fiber lasers have the characteristics of unfixed resonator,high flexibility and low threshold.In recent years,random fiber lasers have been widely paid attention by scholars at home and abroad,and have potential application prospects in ultrafart optical communication,fiber sensing,medical system applications and other fields.This paper mainly conducts experimental research on random fiber lasers.The research contents include multi-wavelength random fiber lasers and pulsed random fiber lasers.Three random fiber lasers with different structures are designed by introducing different filters and Q-switching components.The specific work content is as follows:Firstly,a tunable and switchable multi wavelength random distributed feedback fiber laser based on cascaded Sagnac loop filter is experimentally studied.The filtering mechanism of cascaded Sagnac loop filter is studied,and the simulation diagram and experimental diagram of cascaded Sagnac loop filter are given.By adjusting the polarization controller in the experimental device,stable tunable and switchable single,double,three and four wavelength channel laser output can be obtained.The maximum wavelength tuning ranges of single,dual,and three-wavelength outputs are about 4.5nm,2.6 nm and 1nm respectively.Secondly,a multi-wavelength active Q-switched random fiber laser based on realtime configurable filter and electro-optic modulator(EOM)is experimentally studied.The filtering principle of Waveshaper is analyzed,and the detailed parameters of Waveshaper used in the experiment are given.Waveshaper is used to introduce wavelength dependent loss(WDL)into the laser cavity,so that the side-mode suppression ratio(SMSR)of the output laser is about 25 d B,and the amplitude difference between wavelengths is less than 2d B.Thirdly,an active Q-switched multi wavelength random fiber laser based on Sagnac loop filter and electro-optic modulator is experimentally studied.The mechanism of realizing multi-wavelength filtering with Sagnac ring interferometer is analyzed.An electro-optic modulator is added to the laser.By changing the waveform of the external signal source,the time-domain output of light dark pulse switching is realized.When the pump power exceeds 25 m W,a stable pulse is generated with a pulse width of 1μs.