Open AccessEnhanced third-order nonlinear processes based on Raman resonance
Author(s) -
Li-Ya Pei
Publication year - 2020
Publication title -
wuli xuebao
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.199
H-Index - 47
ISSN - 1000-3290
DOI - 10.7498/aps.69.20200418
Subject(s) - electromagnetically induced transparency , raman spectroscopy , raman scattering , four wave mixing , coherent anti stokes raman spectroscopy , laser linewidth , nonlinear optics , optics , raman cooling , materials science , absorption (acoustics) , polarization (electrochemistry) , resonance (particle physics) , spectroscopy , doppler effect , laser , atomic physics , physics , chemistry , quantum mechanics , astronomy
We observe experimentally huge enhanced four-wave mixing based on Raman resonance in an 85 Rb atomic vapor system. With the decrease of coupling field power or the increase of experimental temperature, the signal tends to be narrowed down in linewidth, and be basically the same spectrum as the stimulated Raman spectroscopy. It is found that the macroscopic polarization interference effect plays a crucial role in determining the nonlinear spectra. Further more, in the Doppler-broadened Λ-type energy level system, there is a strong relationship among electromagnetically induced transparency, four-wave mixing and stimulated Raman spectroscopy. The sharp transparent window in electromagnetically induced transparency can be interpreted as the suppression of Raman gain on the linear absorption of the probe field. However, the four-wave mixing signal is a new field generated by the atomic vapor system, and it comes from the Raman gain which is affected and modified by the absorption and dispersion of the nonlinear optical medium. It shows that in a Λ-type Doppler-broadened system, in essence, both the electromagnetically induced transparency and enhanced four-wave mixing stem from stimulated Raman scattering based on the third-order nonlinear processes, just the spectra of which are from different ways and objects of detection.