The FR2122 optical fiber microphone uses a light-emitting diode as the light source and is incident onto the metal diaphragm through the optical fiber. When the sound signal causes the diaphragm to vibrate, the incident light is modulated by the diaphragm vibration and reflected, receiving the reflected light through the fiber optic. After demodulation, it can be restored to the sound signal.

The audio output of optical fiber microphones is based on analog output of standard audio cables, without the need for any additional preamplifiers or amplifiers. Each optical fiber microphone is individually calibrated during the manufacturing process to ensure consistency in performance and ensure normal operation throughout its lifespan.