A new method of degenerate four-wave mixing is demonstrated. This method uses nanosecond optical pulses from an optical parametric oscillator (OPO) that has a broad bandwidth. The OPO uses a β-BaB2O4 crystal that has a coherence time from 60 to 800 fs and the OPO wavelength can be tuned from 410 to 2600 nm. This Letter also reports the signal decay time constants that correspond to the energy relaxation time constants for plasmon absorption in Au nanocrystals dispersed in Al2O3 films, for absorption in vanadyl oxophthalocyanine microcrystals dispersed in water, and for absorption in a nitrobenzene solution of 4-(N,N-diethylamino)-β-nitrostyrene.
- Multiwave mixing
- Optical parametric oscillation
- Ultrafast phenomena