A 1 × 4 optical splitter for TE modes based on a silicon photonic crystal self-collimation ring resonator

A 1 × 4 optical splitter (OS) is proposed for TE modes based on a self-collimation (SC) effect ring resonator (SCRR) in an air-hole type silicon photonic crystal. A 1 × 4 OS consists of four beam splitters formed by varying the radii of the air holes. Utilizing multiple-beam interference theory, the theoretical transmission spectra at each port in the OS were analyzed. By forming four splitters in a SCRR properly, self-collimation light can come out from four ports with the light-intensity ratio we set. OSs were investigated using the two-dimensional finite-difference time-domain (FDTD) simulation technique. The simulation results have good agreement with the theoretical prediction. Because of its small dimensions, whole silicon material, and air-hole type, this structure may have an important role in photonic integrated circuits.