Millimeter wave, multigigahertz optical modulation by feedforward phase noise compensation of a beat note generated by photomixing of two laser diodes

Abstract

A technique is described for high frequency (up to 100 GHz), narrowband ( approximately GHz) optical modulation by encoding the millimeter-wave signal onto a beat note produced by photomixing of radiation from two 1.3 mu m DFB lasers. The phase noise on the beat note is compensated by a feedforward technique, using a low-frequency external optical modulator which simultaneously encodes the information to be transmitted. The modulation band can be tuned by varying the lasing frequency of one or both of the lasers. The fundamental performance limit of this technique is investigated, and the transmission of a pulsed RF signal at 40 GHz is demonstrated.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>