We present the design and development of a stimulatedudRaman scattering (SRS) experimental set-up using a femtosecond laser system. The set-up involves theudgeneration of (i) a picosecond (ps) narrow-bandwidthud(5–20 cm–1) Raman pump, and (ii) a femtosecond (fs)udbroadband continuum Raman probe pulse (800– 1050 nm) providing the Stokes field, covering vibrationsudin the range 300–2500 cm–1. When the two fieldsudinteract with the system simultaneously, gain featuresudare observed on top of the probe beam at frequencyudcorresponding to the characteristic molecular vibrationudfrequency of the system. The ratio of the probe spectrumudwith and without the Raman pump provides a background-free gain spectrum. We present initial studies on some standard systems, viz. benzene, cyclohexane and β-carotene in CCl4/benzene. These studies indicate that this technique provides a better signal with improved signal-to-noise ratio even for a low acquisition time in comparison with normal Raman spectroscopy.
展开▼
