Numerical Simulation And Theoretical Analysis Of Microstructure Fiber Laser Medium

Compared with step-index fiber,Microstructure fiber(MF) has aroused widespread attention in academic and industry communities because of its particular optical property and flexible structure designing. As a gain medium of laser,it has also become a hot spot and focu s for research.First of all, the development of (MF) laser as the gain-medium, the application of the microstructure and the recent research progress of MF laser are introduced detaily. So far, many methods and models have been developed to study MF and the conventional ones are analyzed and compared in the paper.Secondly, the principium of conventional fiber amplifier and the rate equations to realize the particle number reverse are introduced. During the course, the structure of fiber amplifier, the choice of pump-light, the selection of pump-wavelength and the disadvantage that influences the effect of doped-ion amplifier, will supply the foundation of Er-doped system later.Then, with the effective index model, the MF is considered as a ordinary step-index fiber, and we can study the connection between the fiber structure and its cladding-index by the programme of MATLAB, with which some characteristics about microstructure fibe laser are simulated. Computing the propagation constant of MF, we find that three approximate formulas in the ordinary step-index fiber are applied to MF. The methods about computing the propagation constant are simulated and compared in some condition and we confirm that the numerical value calculation model is correct and accurate.So, the mode-field distribution of different structure fiber and different wavelength is gained by the former theories. With 980nm pump-light pumped by 1550 nm signal-light, the effect on the alterable structure of MF and the output characteristic is simulated in numerical value using the power propagation equation and the rate equation of the Er-doped system in ordinary step-index fiber theory, including the pump- power, the doped-concentration, the output power, the gain and the length of fiber. At last, We carry out corresponding theoretical analysis on the simulating result and the further optimization has been discussed.