Ultrafast luminescence spectroscopy using sum frequency generation

The basic concepts of sum frequency generation are reviewed and its application to the measurement of time-resolved luminescence spectra with subpicosecond time resolution is discussed. The emphasis is on the discussion of those aspects which are important for the optimization of such an upconversion spectrometer. Results of numerical calculations are presented for various nonlinear crystals, and a recently developed upconversion system is reviewed. This system provides excellent time resolution (<400 fs), wide spectral range, large dynamic range, and allows determination of the absolute zero in time delay with high precision. Application of this technique to some problems of current interest in semiconductors is briefly discussed