Study On The Characteristics Of Photonic Crystal Fiber And Its Application In Fiber Laser

As with many unique properties and flexible structural design features, the photonic crystal fiber can be made into large mode area and large numercial aperture of optical fiber, the photonic crystal fiber (PCF) has broad application prospect in the field of fiber laser. With the rising of fiber laser's energy, it is of great importance for the development of fiber laser to design PCF and solve the key technique problems of fiber laser. In this paper, we have conducted a theoretical study and numerical calculation. The main contents are as follows:The effective refractive index, effective mode area, nonlinear, dispersion and loss of photonic crystal fiber by finite element method (FEM) is investigated. The effect of the distance between holes, the air filling factor and the shape of fiber core on the characteristics of photonic crystal fiber is discussed. Basing on these researches, we design a kind of photons crystal fiber structure with high birefringence, low loss and large mode area. We also research the coupling characteristics of multi-core photons crystal fiber, analysis the influences of the air filling factor and filler in hole on mode field and the far field spot. Compare the effective mode area and the quality of far field spot between photonic crystal fibers with single-core and multi-core, which is instructive for coherent beam combining.In this paper, we have deep research on key technologies of photonic crystal fiber laser. The lens-coupling system with high coupling efficiency has been put into theoretical calculation, simulation and experimental research. Then base on beam propagation method (BPM), the characteristics of photonic crystal fiber grating in fiber grating cavity is researched. The effect of the parameters of grating structure and filler in hole on photonic crystal fiber grating has been especially discussed. In addition, the base on finite element method, the temperature distribution in photonic crystal fiber is calculated. The distribution of temperature under different structure of photonic crystal fiber and exterior condition of heat dissipation are also analyzed. We put forward a new way of heat dissipation, which offer an efficient way of reducing the temperature of the photonic crystal fiber under high power.