Linearization of phase-modulated analog optical links using a four-wave mixing comb source

Abstract

We present a novel method for distortion elimination in phase-modulated analog optical links. A small part of the phase modulated signal seeds a four-wave mixing comb source, which generates lightwaves with integer multiples of the phase modulation of the original signal. These lightwaves are scaled and re-combined with the original phase-modulated signal to cancel the distortion generated in the interferometric phase-to-amplitude conversion process. Experimentally, we demonstrate full cancelation of the third-order distortion of the receiver and achieve a 19-dB improvement in the link's SFDR at a 1-Hz bandwidth. This approach is readily extendable to eliminate all relevant higher-order distortion products or synthesize arbitrary phase-to-amplitude transfer functions.