A Research Paper on the Performance Analysis of a Self-Mode Locking High Power Linearly Polarised Fiber Laser

Abstract

In this research a design for high power linearly polarized all-fiber linear cavity lasers with self-mode-locking is presented, and a new theoretical model based on a Nonlinear Schrödinger Equation (NLSE) is developed and implemented on the MATLAB platform. For the design of cavity, Polarization Maintaining (PM) fibers for both the gain medium and the Fiber Bragg Gratings (FBGs) is implemented. The FBG pairs are used to select the lasing wavelength and polarization. The fiber lasers incorporate specially designed FBGs to achieve an extinction ratio larger than 23 dB. The proposed configuration is based on Non-Linear Polarization (NPR) using PM Yb-doped active fiber and two matching FBGs to form the laser cavity. The combination of nonlinearity, gain, and birefringence in the cavity made the laser generate mode-locked pulses in the picosecond range and with high average output power. Experimental data and numerical simulations of the self-mode-locking fiber laser are presented. Main parameters affecting mode-locked pulses and its envelope are identified. The model proposed here explains the self-mode-locking mechanism and the source of the pulse envelope. In this model, it is proven that self-phase modulation (SPM) plays an essential role in pulse formation and shaping.