Tri-detector heterodyne receiver for noise suppression

A novel tri-detector structure and signal processing method to suppress the local oscillator noise for optical heterodyne receiver is proposed. The tri-detector receiver adds a negative feedback loop and a photodetector compared with the traditional dual-detector receiver. Theoretical analysis shows: By use of proper signal processing technique the intensity noise of the local oscillator, which is not only in the direct current component but also in the intermediate frequency component, has been canceled completely.