Linear optics, Raman scattering, and spin noise spectroscopy

TL;DR

This paper explores the unique properties of spin noise spectroscopy (SNS), a nonperturbative optical method that reveals insights into spin dynamics and absorption characteristics, showing its relation to Raman spectroscopy and nonlinear effects.

Contribution

The paper clarifies the apparent contradiction between SNS's nonperturbative nature and its nonlinear-like properties, linking SNS to Raman spectroscopy and highlighting its unique capabilities.

Findings

SNS depends on light power density.

SNS can probe inside inhomogeneously broadened bands.

SNS enables pump-probe spectroscopy without optical nonlinearity.

Abstract

Spin noise spectroscopy (SNS) is a new method for studying magnetic resonance and spin dynamics based on measuring the Faraday rotation noise. In strong contrast with methods of nonlinear optics, the spectroscopy of spin noise is considered to be essentially nonperturbative. Presently, however, it became clear that the SNS, as an optical technique, demonstrates properties lying far beyond the bounds of conventional linear optics. Specifically, the SNS shows dependence of the signal on the light power density, makes it possible to penetrate inside an inhomogeneously broadened absorption band and to determine its homogeneous width, allows one to realize an effective pump-probe spectroscopy without any optical nonlinearity, etc. This may seem especially puzzling when taken into account that SNS can be considered just as a version of Raman spectroscopy, which is known to be deprived of such abilities. In this paper, we clarify this apparent inconsistency.