Three-channels wavelength division multiplexing based on asymmetrical coupling

In order to realize the wavelength division multiplexing (WDM) device with compact channels and high transmission, a novel three-channel WDM device based on a two-dimensional photonic crystal with a square lattice is proposed. Three parallel line defect waveguides are introduced in this structure to control the propagation of light. Elliptical and rectangular resonators are employed to carry out the selection of light wavelengths by the coupling resonant effects. The point defect cavity is placed at the end of the middle waveguide to further filter the wavelengths. We theoretically analyze the effects of the distances between the resonator and the micro-cavity and between asymmetrical resonators on the light propagation by the finite-difference time-domain (FDTD) method. Three different wavelengths (1560, 1580, and 1620 nm) in the communication window range with maximum transmission over 90% are obtained. The findings may provide potential applications in filters, WDM optical communication systems and other optoelectronics devices.