New picosecond laser system for easy tunability over the whole ultraviolet/visible/near infrared wavelength range based on flexible harmonic generation and optical parametric oscillation

A new laser-based and time-correlated single photon counting (TCSPC) detect ion system which allows easy and fast tuning of excitation wavelengths over a broad range from 240 to 1300 nm, with small gaps from 335 to 360 nm and 660 to 720 nm, has been built. The unique combination of a mode-locked Ti:s apphire laser, an optical parametric oscillator, pulse selectors, and harmo nic generators delivers ultrafast laser pulses (1-2 ps) with variable repet ition rates and excitation wavelengths. Performance characteristics of the laser system at different excitation wavelengths are reported and the TCSPC setup, which is characterized by a total instrument response function of 2 5 ps full width at half maximum, is described. Typical TCSPC measurements d emonstrate the capability of the system of deriving decay or species associ ated excitation spectra. (C) 2001 American Institute of Physics.