Optical transceiver with multimode interferometers

A method for optical communication, comprising:

• providing optical circuitry disposed on a substrate and comprising a transmitter, comprising first waveguides and one or more modulators configured to generate an outgoing modulated optical beam at a free-space wavelength λ0 for transmission over an optical communication link, and a receiver, comprising second waveguides and one or more detectors configured to receive and sense an incoming modulated optical beam at the free-space wavelength λ0 from the optical communication link;
• incorporating in the optical circuitry at least one multi-mode interferometer (MMI), which includes a multi-mode waveguide comprising an input face and an output face, the input and output faces being bisected by a longitudinal axis, the multi-mode waveguide having a predefined width transverse to the longitudinal axis, and which includes ports, which are coupled to respective ones of the waveguides and are configured to launch one or more input beams through the input face and receive one or more output beams from the output face, including two or more ports on at least one of the faces;
• and
• offsetting respective locations of the two or more ports transversely outward from the longitudinal axis by at least λ0/300 from respective base transverse displacements that are equal to integer fractions of the width.