Optical Hybrid with a Folded, Tilted MMI

Abstract

An optical hybrid device is disclosed for use in photonic integrated circuits, including coherent optical receivers. The device includes a first multi-mode interferometer (MMI) configured as a 2×4 splitter and a second MMI configured as a 2×2 coupler directly connected to two outputs of the 2×4 MMI. The 2×2 MMI is folded about a midpoint to form first and second serial sections having respective tilt angles. A first phase shift is introduced at an interface tilt and a second phase shift is introduced at the fold, such that the combined phase condition maintains quadrature relationships among four output signals. The folded configuration reduces the required tilt magnitude relative to an unfolded 2×2 MMI, enables a substantially horizontal output section, simplifies routing to output waveguides, and improves manufacturability, yield, and wavelength performance. The folded topology further provides an improved starting geometry for iterative optimization of MMI boundaries.

Dependencies are inferred from the claim text.