Abstract:A novel eight-channel 2-D photonic crystal filter with high channel isolation is presented. The influence of photonic crystal medium column radius on the frequency characteristics of point defect microcavity with fixed lattice constant (540nm) is analyzed by using the FDTD method. The conclusion of the coupling frequency increasing with medium column radius is obtained. In addition, the transmission characteristics of the eight-channel filter are simulated. Results demonstrate that the filtering wavelengths are in the range of 1 510~1 580nm, which coincide with the optical communication system. And the neighboring channel interval is less than 9.5 nm and the channel isolation is above 35 dB.