Abstract
Some optoelectronic differential amplifiers have been developed for gigahertz signal bandwidths.1–3 These previous optoelectronic approaches were based on a balanced heterodyne receiver design. The electrical-to-optical and optical-to-electrical conversion was used to electrically isolate the two input signals. The actual signal subtraction was done electronically. In the optoelectronic differential amplifier we present here we do the signal subtraction while still in the optical domain. We have eliminated the need for a balancing network, increased the usable bandwidth, developed a variable gain mechanism, and improved the linear and spurious free dynamic range over previous opto-electronic differential amplifiers.