Optical-waveguide hybrid coupler

As a novel guided-wave passive device, the optical-waveguide hybrid coupler is proposed and its first known demonstration is reported. The proposed device consists of symmetric and nonsymmetric branching forks connected at a junction. An explanation of the working mechanism is presented. The feasibility of the device is confirmed by constructing and testing the hybrid coupler with an integrated Mach-Zehnder interferometer composed of a Y junction and phase shifters using a Ti-diffused LiNbO(3) waveguide.