Theoretical And Experimental Research On Dispersion Flattened Microstructured Fibers And Devices

These research works described in this dissertation are supported by National Basic Research Program of China (No.2003CB314900) and the Key Grant Project of Chinese Ministry of Education (No. 104046).Microstructured fiber (MSF) commonly consists of a fused silica core surrounded by an array of air holes running along the fiber length. It has many unusual properties compared to conventional optical fiber, such as endless single mode propagation, flexible tailor ability of dispersion, high birefringence etc. Therefore MSF has already found important applications in nonlinear fiber optics, optical communication and many other fields. With respect to optical communication, MSF can be used for bandwidth expansion, dispersion compensation, pulse compression, short soliton transmission and generation of super-continuous spectrum etc. In this dissertation, MSF and related optical communication technologies are studied both theoretically and experimentally. The main contents and achievements are as follows.1. Using Module BeamPROP in commercial software RSoft and Matlab, design new brand MSF with high nonlinear and small negative dispersion. The MSF structure is three-tier air hole with different diameters, the best structure is found to get the value of nonlinearity between 19.7W^-1km^-1 and 22.6W^-1km^-1 with a bandwidth of 100 nm and value of dispersion between -1.2ps/(nm·km) and -2.4ps/(nm·km).2. Analyzing the aspects to increase flatness and broadness of supercontinuum. The above MSF is used to generate supercontinuum, and we change structure of the above fiber to compare the two dispersion and nonlinear, then get two different supercontinuum, verify the result that high nonlinear and small dispersion is the most important effects to generation of supercontinuum.3. We demonstrate all-optical wavelength conversion based on four-wave mixing. We use 30-m dispersion-flattened photonic crystal fiber with anomalous dispersion to run the experiment. For an average pump power of 26dBm, the conversion efficiency is around -19.5dB, covering a conversion bandwidth of 20nm. Then use the dispersion-flattened photonic crystal fiber with small normal dispersion to replace the former one. Compare conversion efficiency and conversion bandwidth between these two different fibers; found they get almost the same conversion efficiency and conversion bandwidth.4. Conversion from a 10Gb/s non-return-to-zero (NRZ) signal at 1547 nm to a 10Gb/s return-to-zero (RZ) signal at 1566 nm has been experimentally verified based on four-wave mixing (FWM) in a highly nonlinear microstructured fiber (HNL-MSF) without the need of an extra NRZ-to-RZ conversion step.