Design and Simulation of Unconstrained Coupling and Extinction Ratios in Compact Symmetrical Optical Directional Coupler on SOI Substrate and Study the Polarization Dependent Insertion Loss with Coupling Parameters

A novel design of slab structured symmetrical optical directional coupler with S-bend waveguides on silicon-on-insulator (SOI) platform has been designed by using R-Soft CAD tool. Beam propagation method is used for light propagation analysis. The simulation results of symmetrical optical directional couplers are reported. We find that the symmetrical directional coupler has lower coupling ratios, higher extinction ratios, and lower insertion losses with waveguide parameters such as width, wavelength, waveguide spacing, and coupling length. Simulation results designate that the coupling efficiency for TE and TM modes can reach about more than 90%, with extinction ratio about 9.7dB when the coupling length is 8mm for both the polarization modes and insertion loss is 0.1dB with same coupling length at 1550nm wavelength. This device is also urgent requirement for communication, high speed computing, optical switch, optical filter, and splitter.