Research On Two-orthogonal-pump Polarization-Insensitive Fiber Optical Parametric Amplifier

Fiber optical parametric amplification(FOPA) based on four wave-mixing(FWM),which has the obvious advantages of large bandwidth, low noise, complete transparence to the signal modulation format and bit rate, has become one of the hot topics in the field of optical amplification technique. This thesis focuses on the polarization-insensitive fiber optical parametric amplifier and its effects on the amplification charateristics of polarization-insensitive FOPA for polarization multiplexing signals. The main contents are as follows:1. In this thesis,the basic theory of FOPA is investigated comprehensively and the physical mechanism of FWM is introduced briefly as well as the method of phase matching.Moreover, the fundamental concept of polarization effect is described in detail.2. The parametric gain expressions of two polarization states are derived from the vector coupled wave equations of two-orthogonal-pump FOPA under the small signal model.By using the Runge Kutta method, the parametric gain characteristics are investigated, where numerical results illustrate the dependence between the parametric gain and polarization of the signal in the small signal model. In the same time, the parametric gain curve is also simulated by considering the pump loss. Furthermore, this thesis analyzes the influence of parameters, including pump powers, fiber nonlinear coefficient and fiber length on the parametric gain. Therefore we can choose appropriate parameters to make the FOPA working in the best state.3. The amplification characteristics of polarization-insensitive FOPA for polarization multiplexing signals are analyzed. By using the split-step Fourier method to simulate the amplification characteristics of the two polarization multiplexing signals, the results show that the two polarization multiplexing signals have the same parameter gain. Moreover, the gain characteristics of two polarization multiplexing signals with different modulation formats(NRZ-OOK, DPSK and QPSK) and different signal powers are studied. Obviously,the polarization-insensitive FOPA can achieve the completely transparent amplification of the polarization multiplexing signal with different modulation formats in the small signal model.