Based On Photonic Crystal Micro Loop Filter Design And Application Of Research

The ring resonator is an important part of the optical integrated devices. With the development of optical communication technology, the requirement of the density of integrated optical devices is increasing. While due to the bend-loss limit, the traditional slab waveguide microring resonator based on total internal reflection can not further reduce the size of the device, and hinder the increasing of device density. Because of the photonic band gap properties, the photonic crystal can not only control the movement of photons perfectly but also can achieve low-loss transmission in the wide-angle bend. In addition, photonic crystal also has the advantages of compact structure, small size, and so on. We have designed the add-drop filter, the T-type filter and the beam splitter based on microring resonator, the impact of parameters change on device performance have been analyzed, which will make great sense to promoting the development of the future optical communication.The main work and research results are as follows:1. The download direction of the add-drop filter based on photonic crystal microring has been analyzed by mode symmetry principles, and according to the time-domain coupled mode theory, transmission coefficient expression of every port has been derived. All the analysis will provide a theoretical basis for the design of photonic crystal microring add-drop filter.2. The basic structure of the photonic crystal add-drop filter based on microring resonator has been designed, and the backward download at1567nm with efficiency of97.8%is realized. It is worth mentioning that the radius of the microring resonator is only1.08um. It fully demonstrates the ultra-compact and high efficiency advantages of photonic crystal microring resonator. The impact of parameter variation on the download spectrum has been studied, and the results show that:backward download at1550nm and forward download at1592nm will be realized at the same time with only one microring when the radius of coupled rods are0.8r, and then we have designed the three-port filter with the output ports on the same side. With the increase of the refractive index of inner rods, the peak wavelength of output port increases from1542nm to1589nm gradually, but the normalized transmission rat of peak wavelength and the Q factor of transmission spectra change little, which can be used to produce tunable add-drop filter.3. In order to reduce the difficulty of design requirement caused by symmetry of degenerate mode and realize multi-channel filtering function, we have designed T-type filter. By appropriate adjustment of the radius of inner rods, three-port filter at the wavelength of1552nm,1567nm and1582nm has been designed. Not only this T-type filter can be extended for multi-port output which can be used in WDM systems effectively, but also does not need to consider the symmetry of resonant mode in microring, which is convenient for filter design. At the same time, we find that the T-type filter will achieve energy equipartition function at a specific wavelength by reasonable parameter adjustment. We briefly discuss the application of T-type filter based on photonic crystal microring resonator in the field of beam splitter. With the combination of T-type filter and beam splitter, we have designed T-type filter-splitter for1550nm, and the efficiency of two output ports achieves46.8%with the radius of inner rods are1.1r. All the studies expand the applications of photonic crystal microring resonator in a certain extent, and lay the foundation for the wide application of photonic crystal microring resonators.