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) detection 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:sapphire laser, an optical parametric oscillator, pulse selectors, and harmonic generators delivers ultrafast laser pulses (1-2 ps) with variable repetition 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 25 ps full width at half maximum, is described. Typical TCSPC measurements demonstrate the capability of the system of deriving decay or species associated excitation spectra. (C) 2001 American Institute of Physics.