Photonic Sampling of RF and Microwave Signals
NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF ELECTRICAL AND COMPUTER ENGINEERING
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Optical sampling of wideband microwave signals has recently gained a lot of attention due to the availability of high repetition rate mode-locked lasers. This report examines the state-of-the-art in mode-locked lasers and their performance requirements when used for wideband signal sampling. The required sample time uncertainty jitter and optical pulsewidth are shown as a function of the Nyquist sampling rate. Nonuniform sampling theory is also presented as a means to quantify the sampling jitter from spectrum analyzer measurements. Various laser configurations and mode locking techniques are discussed with emphasis on the measurement of the laser performance. A summary of the measured pulsewidth and minimum jitter times for a number of lasers reported in the literature is presented. The design for a NRL sigma laser currently being constructed at NPS is also discussed. To relax the requirements on a lasers required sample time uncertainty, 1st and 2nd order optical sigma delta architectures are investigated. Also introduced is an undersampling, optical DFT receiver concept that could allow frequency measurements beyond Nyquist.
- Lasers and Masers
- Electrooptical and Optoelectronic Devices