High Repetition Rate Production of Picosecond Pulses at Wavelength <250 nm
Two of the major challenges to ultrafast laser spectroscopists are the generation of the needed wavelengths and the production of a sufficient transient population for observation. As laser pulses become shorter, this second requirement becomes evermore difficult to meet; to create the same excited population in picoseconds rather than nanoseconds may require 1000 times the peak intensity and a corresponding increase in unwanted nonlinear processes in the sample. In this paper we describe a laser system for generating picosecond pulses with wavelength <250nm at a 5kHz repetition rate. Short pulses from a synchronously pumped dye laser are amplified to a peak power >5MW in a dye medium pumped by a copper vapor laser. The high peak powers allow nonlinear optical techniques to shift the wavelength of the pulses well into the UV as in many of the high-power low repetition-rate laser systems [1–5]. The high repetition rate of the system described here, however, allows for sophisticated signal averaging needed in detecting extremely small populations of transients using pumpprobe picosecond spectroscopy.
KeywordsPicosecond Pulse Copper Vapor Laser 5kHz Repetition Rate Excited Population Single Pass Gain
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