The 1×4 Optical Splitters Based on Silicon Photonic Crystal Self-Collimation Ring Resonators

We report 1 × 4 optical splitters (OSs) with different splitting ratios based on either rod-type or hole-type silicon photonic crystal self-collimation ring resonators (SCRRs). The four beam splitters of the OSs are formed by changing the radii of silicon rods or air holes. The light beam propagating along the SCRR can be controlled by the self-collimation effect. The transmission spectra at the through and drop ports are investigated by using the finite-difference time-domain (FDTD) method. The simulated results agree well with the theoretical calculation. For 1550-nm dropping wavelength, the free spectral ranges for rod-type and hole-type configurations are 28.8 nm and 32.5 nm, respectively, which almost cover the whole optical communication C-band window. The dimensions of these structures are only about 10 μm × 10 μm .