An optical coupling apparatus, comprising: a coupling and polarization beamsplitter, a phase shifter, a 2×2 adjustable beamsplitter, a photoelectric detector, and a microprocessor, wherein the coupling and polarization beamsplitter is configured to: couple light from an optical fiber into a waveguide, and perform polarization beam splitting and rotation to obtain a first transverse electric, TE polarized beam and a second TE polarized beam, the first TE polarized beam and the second TE polarized beam having a phase difference, wherein a ratio of intensity of the first TE polarized beam to intensity of the second TE polarized beam is a 1:a 2; the phase shifter is configured to adjust the phase difference between the first TE polarized beam and the second TE polarized beam based on a working voltage of the phase shifter; the 2×2 adjustable beamsplitter is configured to: adjust a split ratio based on a working voltage of the 2×2 adjustable beamsplitter, and perform beam combination processing on the first TE polarized beam and the second TE polarized beam based on the split ratio to obtain a first output and a second output; the photoelectric detector is configured to: detect a working current of the first output, and send the working current to the microprocessor; the microprocessor is configured to adjust the working voltage of the phase shifter and the working voltage of the 2×2 adjustable beamsplitter based on the received working current; and wherein the microprocessor is configured to: adjust the working voltage of the phase shifter and the working voltage of the 2×2 adjustable beamsplitter, until the working current is less than or equal to a preset threshold. a coupling and polarization beamsplitter, a phase shifter, a 2×2 adjustable beamsplitter, a photoelectric detector, and a microprocessor, wherein the coupling and polarization beamsplitter is configured to: couple light from an optical fiber into a waveguide, and perform polarization beam splitting and rotation to obtain a first transverse electric, TE polarized beam and a second TE polarized beam, the first TE polarized beam and the second TE polarized beam having a phase difference, wherein a ratio of intensity of the first TE polarized beam to intensity of the second TE polarized beam is a 1:a 2; the phase shifter is configured to adjust the phase difference between the first TE polarized beam and the second TE polarized beam based on a working voltage of the phase shifter; the 2×2 adjustable beamsplitter is configured to: adjust a split ratio based on a working voltage of the 2×2 adjustable beamsplitter, and perform beam combination processing on the first TE polarized beam and the second TE polarized beam based on the split ratio to obtain a first output and a second output; the photoelectric detector is configured to: detect a working current of the first output, and send the working current to the microprocessor; the microprocessor is configured to adjust the working voltage of the phase shifter and the working voltage of the 2×2 adjustable beamsplitter based on the received working current; and wherein the microprocessor is configured to: adjust the working voltage of the phase shifter and the working voltage of the 2×2 adjustable beamsplitter, until the working current is less than or equal to a preset threshold.