Design And Study Of Multiplexer/Demultiplexer Based On Photonic Crystal Resonant Coupling

Photonic crystals are artificial materials which possess a periodic modulation of dielectric constant on wavelength scale. They were initially proposed and used in their photonic bandgaps (PBGs) where no guided mode can exist. Typically, waveguides in PhCs are achieved by introducing linear defects, which support guided modes inside the PBGs. Photonic crystal waveguide and resonant cavity are two basic components to constitute a variety of optoelectronic devices which are widely applied due to their compact size and easy integration. In this paper, the characteristics of resonant coupling between photonic crystal waveguides and resonant cavities is discussed as the foundation of WDM.1. The properties of photonic crystal ring resonators (PCRR) and microcavity are obtained by using coupled mode theory. Firstly, they are the size, coupling, and resonator frequency of the factors of influencing performance index of photonic crystal microcavity. Secondly, the transmission coupling characteristics of the light wave in PCRR is studied using finite difference time domain (FDTD) method.2. We study the resonant coupling frequency which stands for the coupling effect between photonic waveguide, PCRR and microcavity is calculated according to the resonant coupling theory. A filter composed of coupling resonant is designed based on the characteristics of resonant coupling between photonic crystal resonators.3. Based on the characteristics of resonant coupling between two PCRR, four cavities with different sizes and waveguides, the demultiplexing of four wavelengths, i.e.3310nm,1550nm,1600nm and1650nm is realized. The numerical results obtained by the FDTD method show that the output efficiency of the four wavelengths can be higher than90%only by modulating the radius of the border rods of output waveguides. The presented device having not only a compact size with12μm×17μm but also a high output efficiency, may have potential application in the future optical communication fields. 4. We proposed a three-wavelength multiplexer/demultiplexer based on the characteristics of resonant coupling between PCRR and cavity. The structure composed of one PCRR and three cavities. The numerical results obtained by the FDTD method show that it can realize the demultiplexing of three wavelengths, i.e.1440nm,1490nm and1550nm only by modulating the radius of the cavities. The designed device not only has a compact size with12μm×11μm but also a high efficiency, may have potential applications in the integrated optics fields.