Photonic A/D converters

Summary form only given. Optical pulses from mode-locked lasers have long been recognized as having nearly ideal timing properties for sampling microwave signals. The pulses are short, and the pulse-to-pulse timing jitter can be held to sub-femtosecond levels. The primary difficulty in this sampling approach has been maintaining linearity in encoding the electrical signal on the optical pulse. A new technique has been developed which views the encoding process in a Mach-Zehnder interferometer as phase modulation, and maintains this treatment of the signal through the measurement, quantization, and processing of the signal. Such an approach has demonstrated third order intermodulation distortion of less than -80 dBc.