Single Mode Multiwavelength Fiber Laser Based On Nonlinear Polarization Rotation

There has been increasing research interest infiber laser sources,because of their potential applications in optical component testing, optical fiber sensor networks and dense wavelength division multiplexing (DWDM) transmission systems ..Single-mode multiwavelength fiber ring lasers are attractive for applications , such as wavelength-division-multiplexing (WDM) communications, fiber-optic sensors, high-resolution spectroscopy, and microwave photonics systems, thanks to the numerous advantages such as narrow linewidth, high power,low intensity noise, and compatibility with other optical fiber components. In this paper ,we have propose an novel single-mode Single-mode multiwavelength fiber ring lasers. Based on the above consideration, the main work of this paper is:First, A novel all fiber birefringent filter has been proposed and demonstrated. Simulation results show that the birefringence fiber filter with one section of polarization_ maintenance fiber (PMF) can be finely tuned with its free spectrum range, and the filter with two sections of PMFs can generate changeable wavelength spacing. Experiment agrees well with simulation. This filter has potential applications for flexible multiwavelength fiber laser.Second, A multiwavelength fiber laser based on nonlinear polarization rotation with up to 18wavelengths has been proposed and demons t rated. The intensity2 and wavelength2dependent loss induced by nonlinear polarization rotation effect is used to alleviate the mode competition in the homogeneous broadening gain medium of e rbium2doped fiber . Instead of t raditional filters , a polarization2maintaining fiber is inserted into the laser cavity ,with which the polarization2dependent isolator composes an equivalent Lyot birefringent fiber filter . The in line birefringence fiber filte r is used to simplify the laser configuration , which benefits systematic integration. The effect of the 980 nm pump power on the multiwavelength gene ration is investigated. It is shown that the p ump power contributes a lot to the evenness of the multiwavelength spectra due to the intensity dependence of nonlinear polarization rotation effect .