Self-homodyne RF-optical LiNbO3 microdisk receiver

AbstractA novel RF-optical receiver architecture based on nonlinear optical modulation in a LiNbO 3 microdisk modulator is presented.This is the first RF-optical receiver without high-speed electronic components for transmitted carrier links. We demonstrate receiveroperation by demodulating 50 Mb/s digital data from a 8.7 GHz carrier frequency. 2005 Elsevier Ltd. All rights reserved. Keywords: RF-optical receiver; Self-homodyne; Nonlinear modulation; LiNbO 3 microdisk modulator 1. IntroductionIn homodyne and super-heterodyne RF receiverarchitectures local oscillators (LOs) and mixers are usedto down-convert and extract the baseband informationfrom the received RF signal. Due to a desire for reducedpart counts, size, weight and power consumption inhigh-carrier frequency short distance applications, self-homodyne and self-heterodyne systems have been pro-posed [1,2]. In a self-homodyne and self-heterodynetransmission system the transmitter broadcasts a RFmodulated signal and the local carrier so the base-band/IF signal can be down-converted by mixing the re-ceived carrier and modulated signal in a nonlineardevice (i.e., a self-mixer). The receiver power consump-tion, phase noise, and complexity are reduced by elimi-nating the LO and the mixer. Although such anapproach suffers from reduced power efficiency, it hasbeen shown that it can lower overall cost and complexityin mm-wave local area networks and indoor wirelesstransmission systems [1]. In this paper we demonstratethat the second-order nonlinearity of an optical micro-disk modulator, biased at its maximum transmissionpoint, may be used to realize the mixing process requiredto extract the baseband signal from the transmitted car-rier RF signal.2. Self-homodyne RF-optical receiverA self-homodyne RF-optical receiver replaces thefunction of a single-ended diode or FET mixer in atransmitted carrier wireless link with a sensitive opticalmodulator that performs down-conversion in the opticaldomain. In this approach the nonlinear dependence oftransmitted optical power (P