Infinera Corporation
SUBCARRIER MODULATION WITH RADIO FREQUENCY (RF) IQ MODULATORS

Abstract:

Methods, systems, and apparatus for subcarrier modulation with radio frequency inphase-quadrature (IQ) modulators. A system includes a plurality of IQ modulators, each configured to receive an input electrical signal comprising an inphase signal and a quadrature signal, and each configured to modulate the inphase signal and quadrature signal based on one of a plurality of local oscillator signals to output a multiplexed signal. Each of the plurality of local oscillator signals is supplied by a respective one of a plurality of local oscillator circuits. A modulator circuit is configured to modulate a carrier optical signal from a laser having a frequency .omega..sub.c based on the multiplexed signal to generate a modulated optical signal centered at frequency .omega..sub.c and comprising a plurality of subcarriers. A center frequency of each of the plurality of subcarriers is offset from .omega..sub.c by a frequency of said one of the plurality of local oscillator signals.