A compact versatile femtosecond spectrometer

A compact apparatus for femtosecond pump-probe experiments is described. The apparatus is based on a cavity-dumped titanium:sapphire laser. Probe pulses are generated by focusing weak (similar to1 nJ) pulses into a microstructure fiber that produces broadband continuum pulses with high efficiency. With the pump pulses compressed and probe pulses uncompressed, the rise time of the pump-probe signals is <100 fs. The 830 nm pump pulses are also frequency doubled to generate light for excitation at 415 nm. The versatility of the spectrometer is demonstrated by exciting molecules at either 830 or 415 nm, and probing at wavelengths ranging from 500 to 950 nm. Some results on the green fluorescent protein are presented. (C) 2002 American Institute of Physics.