Optical balanced homodyne receiver

Abstract

An optical balanced homodyne receiver (300) has an optical mixing element (320) configured to convert a modulated optical input signal (311) into a pair of demodulated optical signals (321, 322) and an opto-electric conversion circuitry (330) configured to convert the pair of demodulated optical signals into a demodulated electrical current signal (331). The homodyne receiver also has a transimpedance, TI, amplifier (360) with capacitive feedback configured to convert the demodulated electrical current signal to a demodulated electrical voltage signal (361) and a DC current cancellation circuitry (380) configured to measure a low frequency current component in the demodulated electrical current signal and to derive therefrom a feedback signal (381). The optical mixing element is tuneable (323) and configured to receive the feedback signal (381) and to adapt an optical power balance between the pair of demodulated optical signals based on the feedback signal such that the low frequency current component is suppressed.

Dependencies are inferred from the claim text.