Research On Coupling Loss Of Photonic Crystal Fiber

Photonic crystal fiber is a kind of new fiber with a flexible periodic arrangement of air hole structure, which has many excellent features such as adjustable dispersion, nonlinearity adjustable and endlessly single-mode transmission. It has huge prospects in the optical fiber communication and optical fiber sensing fields. With the further technology, it is found that the coupling technology of photonic crystal fiber lags seriously hindered the application and development of photonic crystal fiber. Aiming at this problem, the thesis studies the universal coupling technology of photonic crystal fiber and ordinary single-mode fiber. The main work is as follows.According to the "methods to reduce the coupling loss between the two types of fiber", the domestic and foreign research on photonic crystal fiber coupling with ordinary single-mode fiber is classified summary from two aspects of theory and experiment. And the two kinds of fiber optical numerical calculation method, the finite element method and the beam propagation method, are introduced in detail. Then the optical crystal fiber coupling with ordinary single-mode fiber is simulated with the two methods. The numerical results have great consistency with the existing literature. The influence factors of coupling loss are analyzed and the conclusion is got. Based on the existing technology, mode field mismatch is the main reason of coupling loss.In order to reduce the coupling loss between photonic crystal fiber and single-mode fiber, the thesis proposed two methods, selective filling the air holes of the photonic crystal fiber and the photonic crystal fiber uptapering. And based on the beam propagation method, the two methods are studied. The research results show that the two methods works well and have good generality for all kinds of coupling between photonic crystal fiber and ordinary single-mode fiber, and the latter is better. In order to realize the "the photonic crystal fiber uptapering", the "Mold tapering method" is proposed.With the research development of photonic crystal fiber, in recent years, the study of multiple core photonic crystal fiber range increase trend. In the thesis, the influence factors of coupling between multiple core photonic crystal fibers and ordinary single-mode fiber are analyzed. With the application of selective filling method, the coupling simulation is analyzed using the beam propagation method. The results shows that the selective filling method is also applicative for the coupling between multiple core photonic crystal fiber and ordinary single-mode fiber. And choosing fill scheme and filling parameters flexibility can effectively reduce the coupling loss of the two kinds of optical fiber.