Interferometric combinations of frequency-shifted mode-locked-laser pulses.

We describe some optical modulation/demodulation schemes that consist of shifting the optical frequency spectrum of mode-locked-laser pulses and interferometrically combining the shifted pulses. Several forms of frequency shift produced by electrooptic phase modulators driven at frequencies commensurable with the pulse repetition rate are considered. Analyses are made in terms of superposition of phase-modulation sidebands, and expressions are also obtained for the pulse intensity waveform in the time domain as the product of an envelope function times the original pulse waveform. Computed examples are presented.