cw dye laser synchronously pumped by the third harmonic of a modelocked cw Nd:YLF laser for tunable blue and green excitation and picosecond time-correlated photon counting detection

摘要

Abstract: The range of excitation wavelengths for a setup of time-resolved detection of fluorescence was extended with tunable blue by the synchronous pumping of a Stilbene 3 dye laser. A conversion efficiency of over 30% was found when pumping a coherent radiation (CR) model CR590 with extended cavity length using the third harmonic output of a cw mode-locked Nd:YLF laser (CR Antares). For decreasing the repetition rate of excitation pulses, an electro-optic modulator in a dual pass configuration was used. In this way, pulses with durations of less than 4 ps were generated with energies of up to 2.6 nJ and a repetition rate of 600 kHz, fitting very well with the requirements of the time-correlated photon counting detection technique. The tuning range of Stilbene 3 was from 415 to 465 nm. A further extension of the wavelength range is planned by pumping Coumarin 151 (465 - 520 nm) and a mixture of Stilbene 3 and Coumarin 7 (495 - 570 nm) using the same pump laser source. !6