Direct optical detection of pure spin current in semiconductors

TL;DR

This paper proposes a novel optical method using two-color Faraday rotation to directly detect pure spin currents in semiconductors, enabling precise measurement of spin flow characteristics.

Contribution

It introduces a practical scheme based on quantum interference to measure spin currents directly, which was not previously available.

Findings

The Faraday rotation of QUIP depends on spin orientation and wave vector.

The method allows tuning of the rotation via laser phase and polarization.

The scheme enables detection of the magnitude and direction of spin currents.

Abstract

We suggest a new practical scheme for the direct detection of pure spin current by using the two-color Faraday rotation of optical quantum interference process (QUIP) in a semiconductor system. We demonstrate theoretically that the Faraday rotation of QUIP depends sensitively on the spin orientation and wave vector of the carriers, and can be tuned by the relative phase and the polarization direction of the $\omega$ and $2\omega$ laser beams. By adjusting these parameters, the magnitude and direction of the spin current can be detected.