The Tunable Filter Characteristic Analysis Of Mach-Zehder Interferometer Based On Self-collimation Beams In Photonic Crystal

Along with the rapid development of optical communication technology, the Optical Wavelength Division Multiplying(OWDM) technology has become a hotspot research because it can increase the transmission capacity of optical communication systems a hundredfold. As the essential device of OWDM, tunable optical filter also gets more and more attention of people. Using photonic crystal device can control the propagation of photons flexibly, such as semiconductor materials control the movement of electrons. And since the small size of photonic crystal device, it is easy to realize miniaturization and integration. So we can use the characteristics of photonic band gap and self-collimation to manufacture excellent tunable filter, then increase the rate and capacity of the transmission. Therefore, based on the important research significance of photonic crystal tunable filter on the development of the modern OWDM system, we mainly studied a two-dimensional photonic crystal self-collimation Mach-Zehnder Interferometer (MZI) tunable filter and the main contents are as follows:First, according to the basic characteristics of liquid crystal, we analyze the electronically controlled birefringence of liquid crystal effect on effective index of liquid crystal, and we establish the mathematical relationship between the applied voltage and the effective index of the liquid crystal molecules. Then analyze the tunable principle of liquid crystal MZI when combing with the phase modulation principle of MZI.Next, based on numerical calculation method of the photonic crystal, the equifrequency distribution of the two-dimensional square/triangle lattice air holes, silicon dielectric rods photonic crystal and air holes photonic crystal after filling liquid crystal in air holes are studied by using the plane wave expansion method, to obtain the structure for producing the self-collimation MZI tunable filter.Finally, based on the design of the self-collimation beam splitter and reflector, the tunable filter characteristics of photonic crystal symmetry/asymmetry MZI filter are researched. Then we improve the performance of the tunable filter further, by using the optimization methods in better filtering performance asymmetry MZI filter along with series and cascading.