Investigation On Random Fiber Laser Based On Feedback Of Random Phase-shifted Fiber Bragg Grating

Random fiber laser(RFL)is a new spot in research field of fiber lasers in recent years.It can produce continuous,stable,low coherence and multi-wavelength laser emission.So,it is considered to be a new type of light source.This paper uses erbium-doped fiber as gain medium,random phase-shifted fiber Bragg grating as random feedback,to realize the random laser emission with low threshold.1.Three kinds of RFLs based on random distributed feedback by Rayleigh scattering,fiber grating random feedback and random feedback by optical fiber filled with nanoparticles are introduced respectively in this work.The principle of random fiber lasers and the development of experimental research were described in this paper.2.A random fiber laser based on single random phase-shifted fiber Bragg grating(PSFBG),which was fabricated in a common single-mode fiber with 10 random phase-shifted points,has been proposed and experimentally realized in this work.The proposed RFL has instability wavelength laser emission and 2 or 3wavelength peak.The peak wavelengths were 1551.76 nm,1551.94 and 1551.89 nm,namely.The 1551.76 nm wave peak was stable with stable 3 dB bandwidth of 0.13 nm.The intensities of 1551.89 nm and 1551.94 nm wave peaks were very unstable,and sometimes the peak would even disappear.The threshold pump power was 21.2mw,and the output power was 2.75 mw with 200 mw pump power.As the contrast,fiber laser with a common fiber Bragg grating as feedback obtains a single wavelength laser output,with peak wavelength of 1551.93 nm.It was found that the output power has linear dependence on pump power and the output power is 1.58 mw with 200 mw pump power.3.A random fiber laser based on double random phase-shifted fiber Bragg gratings has been proposed and experimentally realized in this work.A period of Er-doped fiber provides gain amplification.It was found that thethreshold was low about 25.2 mw.We obtained stable random lasing emission.Its peak wavelength is 1551.84 nm,and the output power is 2.24 mw with 200 mw pump power.After being replaced by two common fiber Bragg gratings,the new fiber laser has stable single wavelength lasing emission with threshold power of 25 mw.The output power was 2.48 mw with 200 mw pump power.A random fiber laser with a common fiber Bragg grating and a random phase-shifted fiber Bragg grating as feedback obtains stable random lasing emission with threshold pump power of 26 mw.The output power was 1.99 mw with 200 mw pump power.