Application of gain-modulated avalanche photodiodes in phase-sensitive fluorescence spectroscopy

Phase and modulation fluorometry experiments at frequencies up to 875 MHz and lifetime-selective fluorescence detection with picosecond resolution are reported. A high-frequency gain-modulated silicon avalanche photodiode is used as an opto-electronic crosscorrelator which permits 10 ps time resolution and 1 photon per laser period sensitivity. Application of the correlator to fluorescence rejection from Raman spectra is proposed.