Abstract

This paper reports the theoretical and experimental work of an instantaneous frequency measurement (IFM) receiver using an acoustooptic (AO) implementation.¹ A homodyne interferometric dual Bragg cells configuration was used wherein the reference is derived from the input signal by passing through a wideband delay line, a frequency shifter, and a limiting amplifier. Both the I and Q components of the input signal were measured within each channel by an array of IF phase discriminators. From these results the frequency data were determined. A demonstration breadboard of the AOIFM receiver was designed, built, and tested. A compact in-line interferometric bench was chosen which included a laser diode, a pair of efficient gigahertz bandwidth GaP cells, and an array of fiber-fanout detectors. A local oscillator of the IF of 65 MHz was used to provide the frequency offset between the signal and reference. An IF phase discriminator in turn measured the signal phase for frequency determination. Excellent results were obtained from the demonstration breadboard. These performances include 1-GHz bandwidth, 1-MHz resolution, and 55-dB dynamic range. More details on the theoretical and experimental findings are reported.

© 1988 Optical Society of America