Optically Assisted High-Speed, High Resolution Analog-to-Digital Conversion

摘要

An approach that modifies an analog fiber optic link with a recirculating optical loop as a means to realize a high-speed, high-resolution Analog-to-Digital Converter (ADC) is presented. The loop stores a time-limited microwave signal so that it may be digitized by using a slower, conventional electronic ADC. Detailed analytical analysis of the dynamic range and noise figure shows that under appropriate conditions the microwave signal degradation is sufficiently small so as to allow the digitization of a multi-gigahertz signal with a resolution greater than 10 effective bits. Experimental data is presented which shows that a periodic extension of the input signal can be sustained for well over one hundred periods that in turn suggests an electronic ADC speed-up factor of over 100. The data also shows that polarization effects must be carefully managed to inhibit the loops tendency to lase even though the loop itself contains no frequency-selective elements.