The Study Of Mulit-wavel Ength Brillouin Fiber Laser Assisted By The Stimulated Raman Scattering

During the last few decades,multiple-wavelength fiber lasers have attracted extensive attentions due to their potential applications in the fields of wavelength division multiplexing,fiber-optic sensing,and microwave signal processing.Up to now,a variety of methods have been developed to realize multiple-wavelength fiber lasers,such as fiber gratings,nonlinear effect,and Sagnac loop mirrors.The multiple-wavelength fiber laser,which is based on the nonlinear effect in the optical fiber,has many remarkable advantages such as low cost,simple configuration,low sensitivity and high-quality beam and many groups have engaged in the study of the multiple-wavelength.The multiple-wavelength Brillouin-Raman fiber laser(MBRFL)is based on the integration of nonlinear Brillouin and Raman gains and it can used the single mode fiber to achieve the multiple-wavelength laser which has the advantages such as high precision,consistent channel spacing,narrow line width.So it is important to study the MBRFL.The main work of this paper is as follows:(1)To achieve the multiple-wavelength with enhanced performance,we first theoretically analyze the stimulated Raman scattering(SRS)and stimulated Brillouin scattering(SBS)in optical fiber.And we theoretically calculate the threshold of the stimulated Brillouin scattering assisted by the stimulated Raman scattering.According to the result,it can be found that the Brillouin gain is improved and the threshold reduces with the help of the stimulated Raman scattering.(2)We design and optimize two kinds of the multiple-wavelength Brillouin-Raman fiber laser.One used the stimulated Raman scattering effect and stimulated Brillouin scattering effect,which is named the conventional MBRFL.A tunable laser source(TLS)with a maximum optical power of 13 dBm is employed as a Brillouin pump source.Two identical laser diodes used as the Raman pump(RP)sources and the 44 km long single mode fiber is employed as the nonlinear Brillouin and Raman gain medium.When the Brillouin pump power is 13 dBm,19 Brillouin stokes lines with the average power of-21dB are generated.The other one,which is named the novel MBRFL,used stimulated Raman scattering effect,stimulated Brillouin scattering effect,and four-wave mixing effect(FWM),which is named the novel MBRFL.In the novel MBRFL,a micro-air cavity is inserted into the conventional MBRFL and the four-wave mixing is strengthened.Under the same pump power 13dBm,this novel MBRFL holds 40 Brillouin stokes lines with the average power of-19 dBm.Compared with the conventional MBRFL,this novel MBRFL not only can achieve the more number of the Brillouin stokes lines,but also can make the power higher and the amplitude more flatten.