Development of a picosecond time-resolved Fourier-transform spectrometer

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A picosecond time-resolved Raman spectrometer was constructed for the purpose of measuring picosecond time-resolved Raman spectra from various fluorescent molecules and conducting polymers.Wavelength-tunable near-infrared light pulses are obtained as the signal output (wavelength region : 1060-1350 nm) from an optical parametric generator/amplifier (OPG/A) excited with the fundamental output from a picosecond Ti-sapphire regenerative amplifier coupled with the output from a mode-locked Er-doped fiber laser. The near-infrared light pulses thus obtained are used as the probe light for measuring the Raman spectra. A step-scan Fourier-transform (FT) Raman spectrometer is employed for measuring the Raman scattering. The Raman scattering is introduced into the step-scan FT Raman spectrometer. The interference signal from the detector is processed with a box-car integrator and an A/D converter to obtain a Raman spectrum.When the second harmonic (wavelength region : 775-870 nm) of the idler output from an OPG/A is used as the probe light, the Raman scattering is analyzed with a dispersive spectrometer equipped with a CCD detector.Transient species are generated by irradiating either the second harmonic (388 nm) or third harmonic (258 nm) of the output from the Ti-sapphire regenerative amplifier as the pump light. The time-resolved Raman spectrum from the transient species is obtained by the probe pulse with a delay time from the pump pulse.