Study On Theories And Feedback Characteristics Of Random Fiber Lasers

Random fiber lasers have great application value in the field of image transmission,optical communication and medical diagnosis because of their characteristics of low coherence,continuous stability and multi-wavelength output.In this paper,the theoretical and experimental studies on the fiber laser based on the random phase-shifted fiber grating feedback are carried out.The feedback characteristics of the random phase-shifted fiber grating are simulated and experimentally studied,and the output characteristics of the random fiber laser structure proposed in this paper are simulated.In the experimental study,using erbium-doped fiber as laser gain medium,random phase-shifted fiber gratings provide random feedback and narrow-band random laser output with lower threshold power is finally obtained.1.The theoretical model of random phase-shifted fiber grating is established and the transfer matrix suitable for random phase-shifted fiber grating is proposed.The reflection characteristics of the random phase shift fiber grating were simulated.The simulation spectra of the reflected characteristics obtained were highly consistent with the experimental reflection characteristic spectra of the random phase-shifted fiber gratings experimentally written.2.The Giles model with erbium-doped fiber amplification is introduced briefly.Combined with the reflection characteristic spectrum of the random phase-shifted fiber grating obtained by simulation,a random fiber laser structural model suitable for the study in this paper is established.In the MATLAB environment,the simulated random laser output was obtained,and then a reasonable analysis of the random laser simulation spectrum obtained erbium-doped fiber length and random laser output power relationship.3.Under the guidance of theoretical analysis and simulation,we choose a proper length erbium-doped fiber to build a fiber laser system based on random phase-shifted fiber grating feedback.Two types of random fiber lasers are discussed,which are single-sided random phase-shifted fiber grating random fiber laser and two-side random phase-shifted fiber grating random fiber laser.In the 980 nm light source pump,the maximum pump optical power is set to 200 mW.Finally,the unilateral random phase-shifted fiber grating random fiber laser achieves a maximum output power of 2.75 mW with a slope efficiency of 2.1% and a threshold power of 21.2 mW,the bilateral random phase-shifted fiber Bragg grating random fiber laser obtains the maximum output power of 2.24 mW,the slope efficiency is 1.9% and the threshold power is 25.2 mW.The laser output stability of the latter is better than that of the former.