High-sensitivity nonlinear spectroscopy using a frequency-offset pump.
We report the development of a simple method for eliminating coherent background noise and fluctuations from saturation-spectroscopy signals. With this technique, which we believe will also be effective in two-photon and other types of nonlinear spectroscopy, we have routinely observed background-free saturation signals in I2 at 514.5 nm with signal-to-noise ratios within an order of magnitude of the fundamental quantum limit.
Snyder
J J
JJ
Loborotoire de Physique des Lasers, Université Paris-Nord, 93430 Villetaneuse, France.
Raj
R K
RK
Bloch
D
D
Ducloy
M
M