Study On Fiber Lasers Based On Random Distributed Fiber Gratings

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 fiber grating array feedback are carried out.The feedback characteristics of the random fiber grating array are simulated and experimentally studied.In the experimental study,using erbium-doped fiber as laser gain medium,random fiber grating array provide random feedback,and narrow-band random laser output with lower threshold power is finally obtained.1.Three kinds of analysis methods of fiber grating are introduced in detail:coupling mode theory and transfer matrix method.The theoretical model of random fiber grating array is established and the transfer matrix suitable for random fiber grating array is proposed.The reflection characteristics of the random fiber grating array were simulated.The simulation spectra of the reflected characteristics obtained were highly consistent with the experimental reflection characteristic spectra of the random fiber grating array experimentally written.2.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 fiber grating array feedback.Three types of random fiber lasers are discussed,which are single-sided random fiber grating array random fiber laser,two-side random fiber grating array random fiber laser and one-side is random fiber grating array while the other side is long distance single mode fiber.In the 980 nm light source pump.Finally,the unilateral random fiber grating array random fiber laser achieves a maximum output power of 1.5 mW and a threshold power of 12.7 mW,the bilateral random fiber grating array random fiber laser obtains the maximum output power of 3.2 mW,thethreshold power is 11.8 mW and one-side is random fiber grating array while the other side random fiber laser obtains the maximum output power of 11.8 mW,the threshold power is 15.6 mW.