Design And Study Of Highly Efficient Wavelength And Polarization Splitters

Photonic crystal, proposed independently by Yablonovitch and John in1980s, is a new concept and new materials. Its most basic feature is "photonic band gap". There is no state in the band gap, so the propagation of electromagnetic wave is highly prohibited in the photonic band gap. In additional, many new physical properties brought by photonic band gap are widely used in the production of new principle of high-performance optical devices. Compared to the traditional electronic devices, photonic crystal optical devices have higher efficiency, smaller size, and faster processing rate etc. At the same time, it also provides new materials for the photon integration, space photoelectric technology and all optical communication as well as other modern high-tech. Because of its great potential practical value, it attracts large quantities of physics and materials scholars, the research based on photonic crystals present a prosperous situation at home and abroad. Along with the breakthrough of the bottleneck of the preparation, photonic crystal will be sure to cause a photon technology revolution in the new century.The main research contents of this dissertation are as follows:1. Photonic band gap is the most fundamental characteristics in photonic crystals. Of course, the other main characteristic is the local state. The resonator which have very high quality factor can be created by the local state and resonant characteristics. Based on these, we introduced the basic concepts, properties, production and use of the resonator systematically. At the same time, the finite difference time domain method is employed to simulate the behavior of electromagnetic wave and calculate the transmission of the resonator waves. Some methods are also given to improve the quality factor of a resonant cavity.2. We propose ultra-compact wavelength division demultiplexer based on photonic band gap in two dimensional photonic crystals. The structure consists of two different types of lattice, which can separate two communication wavelengths,1310and1490nm. In addition, it also can be used to separate the wavelengths of1310and1550nm if we change the structural parameters. The total size of the present structure is only12.5μm×2.5μm.The transmission efficiency is above97%, and the good performance is verified with plane wave expansion and finite-difference time-domain simulation.3. We proposed and analyzed a novel ultra-compact polarization beam splitter based on resonator cavity in two-dimensional photonic crystal. The two polarizations can be separated efficiently by the strong coupling between the micro-cavities and the waveguides occurring around the resonant frequency of the cavities. The transmittance of two polarized light around1.55μm can be more than98.6%, and the size of the device is less than15μm×13μm, so these features will play an important role in the future integrated optical circuits.4. We study and analysis the propagation and characteristics of light in the structure, and found that by increasing the sizes of air holes in the two rows that are adjacent to the middle slab, there is only one polarization state can propagate in the waveguide within the complete photonic band gap at a specific frequency. Then we proposed a new structure of polarization beam splitter based on the principle. The result of calculation and simulation shows that the device can separate TE and TM modes effectively with a large angle. And the device size is less than17.6μm×9.8μm.We believes it would have potential application in the photonic integrated circuits.