Design Of Two Dimensional Photonic Crystal Multi-channel Filters

Photonic crystal is a kind of artificial material whose dielectric constant is arranged periodically, the two main features are photonic band gap and photon localization. Using these features, the introduction of point defects and line defects in the complete photonic crystal structure, it easily to produce large-scale integration of high-performance?low-loss and micro-sized optics devices. This paper studies the basic structure of photonic crystal waveguides ? micro-cavity and ring resonator, and combined with the coupling characteristics between several structures, design and optimization of multi-channel photonic crystal filters.First, we studied the structural characteristics of the photonic crystal waveguide, and designed the three-channel parallel waveguide filter, with the use of parallel waveguides coupled waves and coupling length of light waves has different selectivity characteristics. In order to improve the efficiency of the filter, increased incidence media column density to reduce the reflection of light, adjusted the coupling medium column radius to reduce the scattering of light. After optimization, the transmittance of 1310 nm, 1490 nm and 1550 nm wavelengths are 82.4%?91.2% and 76.6%, respectively. The three-channel parallel waveguide filter's size is 400.5?m2, and the transmission rate of 1550 nm is only 76.6% because of the relatively large crosstalk between the channels.Secondly, we studied the photonic crystal micro-cavities, and designed a threechannel micro-cavity filter, with the use of micro-cavities and waveguides coupled waves, combined with the micro-cavity resonance's narrow bandwidth and other features, its transmittance of 1400 nm, 1490 nm and 1550 nm are 88.9% ?90.8% and 82.2%. The three-channel micro-cavity filter's size is 400.5?m2, and has the better transmission efficiency than the parallel waveguide coupling and greater flexibility design. However, it is not conducive to large scale integrated channels, because with the number of micro-cavity increases, enlarges the crosstalk in the system, also results in a decreased rate of single channel transmission.Finally, studied the structural properties of the ring resonator, and designed three-channel ring resonator filter, with the use of ring resonator and the waveguide coupling of light-waves, combined with its multi-model of the resonant wavelength and narrow bandwidth characteristics. All the transmittance are more than 96%, and the size is 270.6?m2; On this basis, increased it to five-channel filter, the channel spacing is 8nm, the transmittance are all above 92%, and the size increased 65.3?m2. The three-channel ring resonator filter has High-efficiency?small size and easy to expand, while reducing the crosstalk which may increase as the number of parallel waveguide and microcavities increased.