Frequencyhyphen;modulated shot noise limited stimulated Raman gain spectroscopy

摘要

We demonstrate for the first time an electrohyphen;optic frequencyhyphen;modulated stimulated Raman gain laser system which achieves shot noise limited detection. The frequency modulation technique reduces the otherwise large thermal background produced by absorbing substrates by a factor of 104ndash;105, thereby permitting the full use of the ultrahigh sensitivity which is sufficeint to observe the vibrational spectroscopy of monolayers.