The Design And Optimization Of Multi-channel Photonic Crystal Waveguide Wavelength Division Multiplexer

Wavelength division multiplexing(WDM) is one of the most useful technologies of all-fiber network communication system. The traditional WDM has a large size, high-loss and unstable transmission. Moreover, it is difficult to further reduce the loss or improve transmission stability. Therefore, we optimize three kinds of WDM(including WDM with two-channel three wavelength, three-channel three wavelength and four-channel four wavelength) by using characteristics of the coupling and decoupling between waveguides, which are selected with curved and array waveguide structure type.First of all, we design and study a photonic crystal WDM of waveguide with two-channel three wavelength. By selecting the appropriate super original cell, we establish the model of photonic crystal waveguide wavelength division multiplex, use the plane wave expansion method to calculate the dispersion relation of coupling structure, and find out the corresponding normalized frequency range from 0.369 to 0.484. By adjusting the number and radius of the medium column, and optimizing the device, we implemented the optimization of transmissivity for the three communication wavelength, which are 1310 nm, 1490 nm and 1550 nm.Further, we design and investigate a photonic crystal waveguide wavelength division multiplexer with three-channel three wavelength. By changing photonic crystal refractive index of medium column, the radius and the normalized frequency of coupling point, we suggest a photonic crystal WDM with three-channel resonance coupling structure. For two different wavelength(1490 nm and 1440 nm), a new resonance coupling area are formed by increasing the radius of medium column. For all the considered light waves, transmission rate will be increased dramatically by increasing the radius of the medium column. For the wavelength of 1310 nm, the transmission rate are increased to 95.5% by changing the radius of medium column.Finally, we design and investigate a four-channel four wavelength photonic crystal waveguide wavelength division multiplexer. By using the resonance coupling between waveguides, four wavelength(1310 nm, 1490 nm, 1550 nm and 1670 nm) of lights are transmitted in their respective channel, leading to implement the function of WDM. By changing the radius of the coupling region media column and adding a certain amount of medium column, the optimal effect is achieved for the transmission rate of light in the waveguide. The spectrum transmittivity of four wavelengths has been reached to 94%, 87%, 89% and 94% respectively, and they all have a good transmission performance.