State of the art and perspectives of the devices with the optical WGM resonators in time and frequency metrology

Abstract

One of the most important tasks in the metrological support of time and frequency measurements is a development of an extremely stable narrow-bandwidth laser sources and oscillators of the sets of the equidistant narrow optical spectral lines (the so-called “optical combs”). These devices are necessary for the transmission of the reference frequency signals and for use as part of mobile sources of time and frequency reference signals in optical and microwave spectral ranges. They are also required for precision ultra-high resolution spectroscopy. A promising direction for the creation of highly stable narrow-band lasers and optical combs is the use of miniature optical whispering gallery modes resonators. Recently, research has been actively performed on the properties and manufacturing techniques of such resonators, as well as devices using them. The article provides a review of current research into applications of optical whispering gallery mode resonators in time and frequency metrology. Main advantages and disadvantages of such devices and prospects for their further use are discussed. The authors review in detail some examples of existing laboratory setups of Russian and foreign scientific groups.