Search results for "Raman cooling"
showing 4 items of 4 documents
High-resolution non-linear Raman spectroscopy in gases
1990
The resolution in the Raman spectra of gases has been greatly improved by the development of the different methods of non-linear Raman scattering. When two laser beams, one of which has a tunable frequency, are focused in a sample, a stimulated Raman process occurs as soon as the frequency difference between the two lasers is equal to a Raman-active rovibrational or rotational transition frequency. The Raman resonance can be detected in different ways: by coherent anti-Stokes Raman scattering (CARS) or the corresponding Stokes process (CSRS), by a gain in one of the beams (stimulated Raman gain spectroscopy, SRGS) or a loss in the other (inverse Raman spectroscopy, IRS), or even by detectio…
Influence of parametric four-wave mixing effects on stimulated Raman scattering in bimodal optical fibers.
2007
We analyze stimulated Raman scattering in normally dispersive bimodal fibers under single-frequency pumping conditions. Experiments show that whenever the interacting nonlinear waves propagate in the LP(01) and LP(11) modes, a parametric four-wave mixing enters unavoidably into play in the wave-coupling behavior, which causes qualitatively different phenomena compared with the ordinary process of Raman scattering, such as the parametric suppression of the first-order Raman Stokes radiation.
Excitonic model for second-order resonant Raman scattering.
1994
A theoretical model for second-order resonant Raman scattering is presented. The effect of Coulomb interaction between electrons and holes is fully taken into account in the framework of the effective-mass approximation. By introducing discrete and continuous excitonic intermediate states in the Raman process, an explicit expression for the Raman scattering efficiency is given for long-range Fr\"ohlich electron-phonon interaction. The model developed can be used to evaluate Raman profiles around the resonant region. A closed-form expression for all matrix elements of the exciton-phonon interaction is obtained once the Coulomb problem for the relative electron-hole motion is separated in sph…
Inelastic neutron and low-frequency Raman scattering in a niobium-phosphate glass for Raman gain applications
2011
Abstract We present measurements of the vibrational spectrum of a binary niobium-phosphate glass in the THz frequency range using inelastic neutron and Raman scattering. The spectra of these glasses show a low-frequency enhancement of the vibrational density of states (“boson peak”). Using a recently developed theory of vibrational excitations in disordered solids we are able to reconcile the measured neutron and Raman spectra using fluctuating elastic and Pockels constants as a model concept. As the spontaneous Raman susceptibility is a key parameter for Raman amplification our results suggest a significant gain profile for application of niobium-phosphate glasses in Raman amplifiers.