International audienceWhispering-gallery modes (WGM) on a spherical surface were first described by Lord Rayleigh at the beginning of the last century, but only after the invention of laser did they start to have some scientific relevance and only during the last two decades there has been a substantial move towards real devices and practical applications. WGM resonators have peculiar properties, the most notable being the potential of having an ultrahigh quality factor Q, which makes them very appealing both as laser cavities and as extremely sensitive sensors. Among the different types of WGM resonators, the microspherical ones represent a very important category, due to their simplicity, easy fabrication, and very high quality. In this review we provide a description of their fundamental properties and we summarize recent works on their application as filters, sensors and lasers
We demonstrate a cavity-enhanced room-temperature magnetic field sensor based on nitrogen-vacancy centers in diamond. Magnetic resonance is detected using absorption of light resonant with the 1042 nm spin-singlet transition. The diamond is placed in an external optical cavity to enhance the absorption, and significant absorption is observed even at room temperature. We demonstrate a magnetic field sensitivity of 2.5 nT/Hz, and project a photon shot-noise-limited sensitivity of 70 pT/Hz for a few mW of infrared light, and a quantum projection-noise-limited sensitivity of 250 fT/Hz for the sensing volume of ∼90 μm×90 μm×200 μm.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.