Optical phased array chip with contra-directional coupler, optical phased array system and on-chip phase calibration method

An optical phased array chip with a contra-directional coupler, comprising:

• m levels of beam splitting section, each level of the beam splitting section comprises an optical splitter group and an optical waveguide branch group;
• each optical splitter in each level of the optical splitter group is configured to divide an optical signal into an N-channel output signal;
• an m-th level of the optical waveguide branch group comprises N paths of first optical waveguide branch, configured to transmit the N-channel output signal;
• each path of the first optical waveguide branch in the m-th level of the optical waveguide branch group is arranged with a thermo-optical phase shifter, and an end of each path of the optical waveguide branch in the m-th level of the optical waveguide branch group is connected to an emitting element;
• an upper layer or a lower layer of each path of the optical waveguide branch in the m-th level of the optical waveguide branch group is arranged with at least one contra-directional coupler, the contra-directional couplers in two paths of the first optical waveguide branch combine light by two paths of second optical waveguide branch and form an interferometer structure, and the interferometer structure is configured to transmit an optical signal after being combined and interfered to a detector for a phase calibration, wherein the first optical waveguide branch and the second optical waveguide branch are locating in different layers in a space.