Study On Novel Dual-Wavelength Brillouin Scattering And Erbium-Doped Fiber Laser, And Their Longitudinal-Mode Selection

Dual-wavelength single-frequency fiber lasers have been extensively studied because of the has a wide range of applications in areas such as dense wavelength division multiplexing systems,optical communication systems,optical fiber sensing systems,Optical signal processing,microwave signal generation and optical instrument testing,due to the advantages of simple construction,low phase noise,narrow linewidth.In this paper,a Stimulated Brillouin Scattering dual-wavelength fiber laser is used to achieve selective mode selection by using stimulated Rayleigh scattering and erbium-doped fiber uniform broadening.A single longitudinal mode fiber laser based on Superimposed Fiber Bragg Gratings using composite cavity structure is proposed.Theoretical and experimental research on the above issues.The followings are the major innovations and contents of this work:1.The theoretical study and experimental verification of the Stimulated Brillouin Scattering theory show that the frequency shift phenomenon occurs with the increase of pump power in the long single mode fiber.A simple configuration dual-wavelength fiber laser,by combining the first-order Brillouin laser and the residual pump laser,is proposed and experimentally demonstrated.With the good tunability of the Tunable lasers(TLS),the dualwavelength fiber laser has a tunable range of ?130 nm,dual-wavelength lasing can be achieved with a high optical signal to noise ratio(OSNR)of >80 dB,and the total power fluctuation is less than 2 dB during the whole tuning operation,and simultaneously the beat frequency of the two lasing wavelengths can be tuned from 10.1875 to 11.0815 GHz with the tunable range of 0.8940 GHz.The high stability of the dual-wavelength operation is experimentally verified by the measured beat frequency fluctuation of ?6 MHz in 1 h and power fluctuation of ?0.03 dB in 2 h.2.A method to significantly suppress the number of oscillating longitudinal modes in a long cavity Brillouin fiber laser is proposed and experimentally demonstrated.The distance between two adjacent fiber tapers is about 5 m.The tapered fiber can be used to generate enough stimulated Rayleigh scattering feedback to suppress the number of the oscillating longitudinal modes and narrow the laser linewidth significantly,when the pump laser operates at 1547.968 nm,OSNR is larger than 55 dB and the wavelength spacing is about 0.81 nm.3.A single longitudinal mode dual-wavelength fiber laser based on Superimposed Fiber Bragg Gratings is proposed and experimentally verified.Numerical simulation of the proposed composite cavity and analysis of its mode selection characteristics,and study on superimposed fiber Bragg gratings filtering characteristics.Dual-wavelength lasing can be achieved with a high optical signal to noise ratio of >80 dB,when the laser operates at 1543.910 nm and1544.000 nm,and dual wavelength beat signal is 10.6963105 GHz.Dual-wavelength lasers provide a good source of laser light for high-quality microwave signals.Polarizationmaintaining fiber grating(PM-FBG)is used as a wavelength filter to achieve stable output of dual-wavelength laser.