MEMS optical microphone

An MEMS optical microphone, comprising:

• a case comprising a cavity and a sound inlet that communicates the cavity to outside;
• a membrane suspended in the cavity and closes the sound inlet;
• a waveguide plate suspended in the cavity and located at a side of the membrane away from the sound inlet, wherein a through-hole passes through the waveguide plate, and an input waveguide and an output waveguide are provided at two opposite sides of the through-hole, respectively;
• a variable optical waveplate provided between the membrane and the waveguide plate, wherein the variable optical waveplate comprises a first end connected to a surface of the membrane facing away from the sound inlet, and a second end extends into the through-hole;
• and
• the variable optical waveplate moves back and forth along a first direction along as the membrane vibrates and deforms;
• an optoelectronic module comprising an electromagnetic radiation source and a sensing part that are provided at two opposite sides of the waveguide plate, respectively, wherein a first light path emitted from the electromagnetic radiation source is coupled into the waveguide plate;
• the first light path enters the sensing part after sequentially passing through the input waveguide, the variable optical waveplate and the output waveguide;
• and the variable optical waveplate is configured to convert an input polarization state of the first light path into an output polarization state, which varies as a moving distance of the variable optical waveplate along the first direction;
• and
• an IC module electrically connected to the membrane and the optoelectronic module;
• wherein a reference guide is provided on the waveguide plate, and a second light path emitted from the electromagnetic radiation source enters the sensing part through the reference guide.