Fiber Coupled 90° Optical Hybrid

SKU: FCOH

The FCOH is a passive, micro-optics-based 90° optical hybrid designed for coherent optical signal demodulation, including BPSK and QPSK formats. It functions by mixing the incoming signal (S) with a local oscillator reference signal (L), generating four optical outputs corresponding to the vector sums and differences of the two inputs: S+L, S−L, S+jL, and S−jL. These outputs represent four quadrature states in the complex optical field space. The signals are then directed to two pairs of balanced photodetectors, enabling differential detection of the in-phase (I) and quadrature (Q) components. This configuration allows extraction of both amplitude and relative phase information through digital signal processing. In a coherent receiver system, preserving the optical phase enables advanced functionalities such as dispersion compensation and phase noise mitigation in the electrical domain, improving overall system performance and enabling cost-effective compensation of optical transmission impairments. A block diagram illustrating the integration of the 90° Optical Hybrid in a coherent receiver is shown below.