The Design And Performance Analysis Of Wavelength Division Multiplexers Based On The Coupling Of Ridge Waveguide And Photonic Crystal Waveguide

Wavelength division multiplexer is an important device in the wavelength division multiplexing (WDM) system. With the merits of flexible design, low loss and small size, the photonic crystal (PC) has been widely used in various optical communication devices including beam splitter, WDM multiplexer and demultiplexer. The wavelength Division Multiplexer fabricated by coupling the optical wave into the photonic crystal waveguides (PCW) can realize high efficient demultiplexing, which has important application in the WDM system.Firstly, by using plane wave method the band gap properties of the two-dimensional PC and PCW based on GaAs material are discussed, the band gap variation with the ratio of dielectric cylinder radius to lattice period is analyzed, and the parameters of two-dimensional PC and PCW are determined. Secondly, a method using6one-dimensional slowly-varying dielectric cylinders coupled into the cosine type edge of the PC is proposed. The coupling efficiency of light between ridge waveguide and PCW is improved by this method. The coupling efficiency achieves more than99%in the wavelength range from1.51μm to1.64μm by simulation. Thirdly, according to the coupling mode theory of point and line defects, a wavelength division multiplexer with a channel interval of20nm based on ridge waveguide and PCW is designed in this wavelength range. The performance characteristics, such as insertion loss, channel isolation, return loss and response time of the device, are analyzed by numerical simulating using finite difference time domain method. Simulation results demonstrate the size of the wavelength division multiplexer as small as29.7μm×20.7μm, the dropping efficiency of more than97%, the insertion loss of less than0.12dB, the return loss of less than22dB, the channel isolation of more than23dB, and the response time of4ps in each channel. Therefore, this device reveals the advantages of small size, high performance and easy integration. Finally, the applications and prospects in integrated optics and fiber to home technology of the wavelength division multiplexer are briefly discussed.