Polarization-insensitive 90-degree spatial optical mixer

The invention belongs to the technical field of free space optical communication equipment, and discloses a 90-degree spatial optical mixer insensitive to polarization. The mixer comprises a first half-wave plate, a phase modulator, a second half-wave plate, a third half-wave plate, a first quarter-wave plate, a second quarter-wave plate, a first polarization beam splitting interface, a second polarization beam splitting interface, a first beam splitting interface, a second beam splitting interface, a first reflection interface and a second reflection interface. According to the polarization-insensitive 90-degree spatial light mixer provided by the invention, the input signal light is subjected to polarization beam splitting, so that the two polarization components of the signal light are respectively mixed with the two components with the same amplitude of the local oscillation light, and the polarization-insensitive light mixing can be realized only by carrying out phase modulation on one of the local oscil