Interference with (Pseudo) Thermal Light; The Hanbury Brown and Twiss Effect

TL;DR

This paper reviews the Hanbury Brown and Twiss effect, its historical development, theoretical basis, and demonstrates correlation measurements of pseudo-thermal light using a Michelson interferometer in a laboratory setting.

Contribution

It provides a comprehensive overview of the HBT effect and presents experimental results on intensity correlation of pseudo-thermal light in a controlled environment.

Findings

Correlation in pseudo-thermal light can be observed using a Michelson interferometer.

The HBT effect is applicable in laboratory settings for studying light coherence.

Historical context and theoretical framework of the HBT effect are summarized.

Abstract

The correlation of light from two sources leads to an interference pattern if they belong to a specific time interval known as the coherence time, denoted as $\Delta \tau$. The relationship governing this phenomenon is $\Delta \tau \Delta \nu \approx 1$, where $\Delta \nu$ represents the bandwidth of the light. This requirement is not satisfied, and hence, interference fringes are not observable in the case of ordinary (thermal) light. In the 1950s, Robert Hanbury Brown and Richard Q. Twiss explored interference phenomena using a narrow bandwidth of thermal light. This investigation led to the discovery of the Hanbury-Brown and Twiss effect (or the HBT effect in short), which has since found applications in various fields, particularly stellar observations and quantum optics. This article briefly traces the history of the HBT effect and its applications in various fields, including stellar observations. More importantly, it outlines the basic theoretical framework of this effect, followed by the design and results of the correlation in intensity fluctuation of a pseudo-thermal light in a college laboratory setting (Michelson interferometer).