Wavelength Tunable Random Fiber Laser Based On Random Distributed Feedback

Random fiber laser(RFL)as the continuation and development of traditional fiber laser,has no fixed resonator cavity because of random distributed feedback mechanism.So,it has the advantages of simple structure,high conversion efficiency and high reliability,and has attracted extensive attention and research in academia in the past decade.Multiwavelength RFL and pulse RFL have potential applications in the fields of optical imaging,sensing,ultrafast optical communication,laser processing and medical applications.However,it is challenging to control the output of RFL due to the existence of complex random patterns.In this paper,the problems mentioned above are studied as follows:1?The multi-wavelength switchable and tunable RFL based on double Sagnac loop filter is studied experimentally.A stable switchable laser output of single,double,three and four wavelength channels can be obtained by adjusting the polarization controller.The central wavelength is variable,and the wavelength interval can also be changed among 2.5 nm,5 nm and 7.5 nm.When the pump power is 300 mw,the average output power intensity is about-24 d Bm.And the wavelength drift is less than 0.2nm,and the power fluctuation is less than 1.5 d Bm within 1 hour.2?Tunable multi-wavelength stimulated Brillouin scattering(SBS)Q-switched RFL based on SMF is studied experimentally.The number of output wavelength varies from 1 to 18 by adjusting the pump power and tunable laser source(TLS)power,and the wavelength interval of laser output is 0.08 nm.The repetition rate and peak power of SBS Q-switched pulse change linearly with pump power and TLS power,while the average pulse width fluctuates between 0.93?s and 1.05?s.The multi-wavelength output is tunable in 38 nm range by changing the TLS wavelength.And the pulse repetition rate will also change with the change of TLS wavelength.3?The wavelength tunable injection locked RFL is studied experimentally.A stable single wavelength can be obtained by injecting a wavelength tunable laser into the cavity of RFL with un-stable output.The injected light power threshold of wavelength locked increases inversely exponentially with the increase of pump power.Different laser modes with stable central wavelength and peak power can be selected by changing the wavelength of injected light within the 0.8 nm random phase shift fiber Bragg grating reflection bandwidth.The output power increases linearly with increasing pump power,and the slope efficiency is about 40%.