Photonic Crystal Fiber And Its Applications In Microwave Generation

Photonic crystal fiber （PCF） caused more and more attentions for its excellentproperties. It is a new type of fiber, whose cladding is a periodic structure consisting ofmagnitude wavelength air holes. To optimize the mode field distribution, dispersion,birefringence, and nonlinearity, people often design its structure flexibly, such as the useof optical asymmetry in the geometry can receive high birefringent PCFs. The maincontributions are as follow.For symmetric structure always results in symmetrical mode field distribution.Therefore, it is hard to receive high birefringence as reaching symmetric mode. In orderto solve those problems above, this thesis presents a high symmetry of the mode fielddistribution and high birefringent Photonic Crystal Fiber （PCF）, with uniform size ofellipse air holes arranging like diamond. A full-vector finite element method is used tosimulate the fundamental mode field distribution, effective mode area, birefringence anddispersion. Circle air-holes PCF having the same parameters are also computed tocompare with it. Both these fibers have high symmetry mode field, nearly circular,making it coupled with other optical devices easily. Meanwhile, it is achieving highbirefringence, elliptical air-holes PCF up to10-3.Based on the excellent characteristics of photonic crystal fiber （PCF）, a method ofoptical microwave generation using its character of high birefringence is proposed byheterodyne method with one laser beam. To design a high birefringence of PCF, a fullvector finite element method is used. Theoretical analysis and results show that themicrowave signal frequency is proportional to the birefringence degree in a certain rangewith the continuous pulse laser injection. When the birefringence nis the odd times of1.94×10^-4, the phase mismatch degree of polarization mode becomes maximal, andmicrowave frequency can reach a maximum value25.91GHz. Meanwhile, when thebirefringence nis the even times of1.94×10^-4, the phase of polarization modematches and the microwave disappears. The simulation results demonstrate the feasibilityof optical microwave generation using high birefringence photonic crystal fiber.