The design of a novel photonic crystal waveguide power splitter is presented.The proposed power splitter has three output ports,the coupling among three parallel photonic crystal waveguides can be considered as a multimode interference(MMI),and the positions of output waveguides are determined by those of twofold images which are formed by the self-imaging effect of multimode interference.The transmission characteristics of the splitter are investigated by using the finite-difference time domain(FDTD) and the plane wave expansion method.The output optical power in each port can be controlled by adjusting the radius of the dielectric rods in the coupling region,and the coupling effect among output ports is decreased by using the T-shaped output port.The results indicate that 1 × 1,1 × 2 and 1 × 3 type power splitters can be realized when the normalized radius of dielectric rods in the coupling region is 0.130,0.180,0.152 or 0.221,respectively.
A high channel-count comb filter based on multi-concatenated sampled chirped fiber Bragg gratings （MC- SCFBGs） is proposed and optimally designed by using several chirped gratings with different fundamental grating periods, instead of non-grating sections of SCFBGs. The numerical simulations of the reflection spectra show that the channel spacing and the channel bandwidth in MC-SCFBGs are smaller than those in multi-concatenated chirped fiber Bragg gratings （MC-CFBGs） and that the spectral bandwidth of MC-SCFBGs can be greatly broadened by increasing the cascade number of the grating sections in each samDling Deriod.
