Optimization of dual-wavelength cascaded Raman fiber lasers using an analytic approach

In this paper, an approximate analytical method is developed to solve the coupling equations which characterize the dual-wavelength cascaded Raman fiber laser with a low reflective fiber Bragg grating as the output reflector for intermediate Stokes radiation. Good agreement between analytical results and numerical simulation is demonstrated and accordingly optimization of the dual-wavelength Raman fiber laser can be discussed analytically. The results show that there exists a set of optimal length of Raman fiber and reflectivity of output fiber Bragg grating for the first and second Stokes radiations to maximize the output power while maintaining the output power of the first and second Stokes radiations equal.