Picosecond pulse generation in longitudinally pumped dye laser generators and amplifiers is studied experimentally and theoretically. Frequency-tunable pulses between 720 and 940 nm are generated with a picosecond ruby laser pump source. The amplification of spontaneous emission and of seeding pulses in the generator and amplifier cells is investigated. Stimulated emission cross-sections and excited-state absorption cross-sections are determined by computer simulations. The coherence properties of the generated radiation are analysed. Resonance Raman contributions are resolved.

The intensity-dependent transmission of picosecond ruby laser pulses of different duration through methanolic and ethanolic solutions of rhodamine B and rhodamine 6G is analysed. The transmission is affected by S 0 -S" two-photon absorption, by stimulated emission at the pumplaser frequency, by amplified spontaneous emission and by excited-state absorption. Various parameters involving the two-photon absorption dynamics are determined by comparing experiments with numerical simulations.

No abstract

No abstract

Abstract. Passively mode-locked ruby-laser pulses are used to generate nearly diffractionlimited picosecond light pulses in a dye cell by longitudinally amplified spontaneous emission. The output pulses are amplified in three longitudinally pumped dye cells, then spectrally filtered with a grating spectrometer and finally reamplified in a fourth dye amplifier in order to generate intense frequency tunable picosecond light pulses. The arrangements applying amplified spontaneous emission (ASE) may be grouped into longitudinally pumped [8][9][10], transversally pumped [11][12][13], and travelling-wave transversally pumped systems [14][15][16][17][18]. In longitudinally pumped systems the amplification of spontaneous emission is limited by excitedstate absorption of the pump laser light [19]. In transversally excited dye cells the duration of the amplified spontaneous emission signal is restricted by the transit time of light through the pumped region, and two pulses are emitted in opposite directions. The travelling-wave transverse pumping technique uses a grating for matching the propagation of the pump pulse and the amplified spontaneous emission signal. It avoids the drawbacks of longitudinal (excited-state absorption of pump pulse) and transverse pumping (limitation of duration, double pulsing). PACSIn this paper we describe a versatile longitudinally pumped dye laser generator-amplifier system that generates intense frequency tunable picosecond light pulses and avoids the problems of pump-pulse excitedstate absorption. The light generation is initiated by amplified spontaneous emission in a dye generator cell. The output signal is amplified in a chain of longitudinal amplifiers, and spectrally narrowed and tuned with a spectrometer. Overall conversion efficiencies (output dye-laser pulse energy to total input pump pulse energy) of about 10% are achieved. Amplification ConsiderationsThe light generation in a longitudinally pumped dye generator cell is limited by excited-state absorption. Pump-laser