Multiple wavelength-selecting and beam-splitting photonic crystal functional device based on the mode coupling between the central microcavity and the adjacent waveguides.

Abstract

The beam-splitting and wavelength selecting characteristics of the two-dimensional square-lattice photonic crystal with a rectangular microcavity and adjacent W1-type waveguides are studied. Based on the abundant defective modes with different symmetries supported by the central microcavity, a multiple-functional device with the abilities of beam splitting and wavelength selecting is achieved. Through altering the connecting location between the input/output channels and the central microcavity, the proposed device can achieve three kinds of functions at different wavelengths within an ultra-small wavelength band of about 3nm, a maximum transmittance of 0.57, and signal-to-noise ratio of 149 are achieved for the one-channel selecting, 0.31 and 146 for two-channel splitting, and a maximum transmittance of 0.24 for the three-channel light beam sharing. The corresponding forward directions of light propagation along the output channels can also be flexibly adjusted.