Sensing with Light

TL;DR: In this article, the authors introduce light-based sensing applications, such as the gravity-wave detection and optical clocks, and briefly introduce some of the light spectrum properties and their applications in metrology.

Abstract: The interaction of highly coherent light and matter is the key in the science of measurement. In the classical electromagnetic theory, the absorption and dispersion properties of the light propagation in a medium are described by the classical Lorentz oscillator model. The unavoidable phase and intensity fluctuations of a light field, which are commonly characterized by the first- and second-order correlation functions, respectively, broaden the light spectrum and restrict its practical applications in metrology. In order to suppress the spectral linewidth, the light’s frequency is usually stabilized to an optical resonator. Several light-based sensing applications, such as the gravity-wave detection and optical clocks, are briefly introduced.