Integrated photonic coupler based on frustrated total internal reflection

An optical coupler for integrated photonic circuits is presented and analyzed. The coupler is based on frustrated total internal reflection (FTIR) and offers high efficiency in a compact footprint. Analytic expressions for the transmission and reflection coefficients of the coupler are obtained using a plane-wave theory and experimentally verified. Finite-difference time-domain modeling of FTIR is discussed and modeling results of the coupler are presented. A parametric discussion of the FTIR coupler provides design tools for making 3 dB couplers.