An Optical Mixer-Preamplifier for Lightwave Subcarrier Systems
01 January 1988
An optical traveling-wave amplifier (TWA) is used as a combined mixer and preamplifier for 1.3micron wavelength subcarrier-modulated optical signals. By modulating the TWA gain at the local-oscillator frequency f sub (lo), sum and difference frequencies (f sub s +- f sub (lo)) are generated, where f sub s is the frequency of intensity modulation of the input subcarrier signal. If residual reflectivity from the TWA facets is small, then the measured conversion efficiency is as predicted by a simple model. Operation at frequencies greater than 1 GHz is limited by the modulation response of the gain.