Single-longitudinal-mode selection in a nanosecond-pulsed dye laser

We investigate the dynamics of the excited-state population, the cavity photon number, and the spectrum of an optically pumped nanosecond-pulsed dye laser containing bandwidth-narrowing elements in the cavity. We show that, in order to achieve single-mode operation, the pump-pulse duration has to be long enough and the dye concentration sufficiently high. This is partly due to the frequency shift of the laser spectrum during the decrease of the excited-state population towards its steady-state value. We demonstrate a single-mode dye laser, where single-mode selection is realised with the aid of an intracavity Fox–Smith interferometer. In this way we have obtained 5-ns-long pulses at the wavelength of 590 nm with a pulse energy of 6 mJ and a spectral width of 100 MHz (FWHM).