An optical heterodyne mixer providing image-frequency rejection

Abstract

This paper describes an optical heterodyne mixer which detects a desired signal at frequencyf_{LO} \pm f_{IF}while rejecting interference from any signal at the image frequencyf_{LO} \pm f_{IF}. Implementation of the mixer is relatively simple. Its performance is insensitive to fluctuations in the optical dimensions of the circuit. This mixer is particularly attractive for communication systems using wavelength division multiplex techniques.