Nonlinear optical filter with ultranarrow bandwidth approaching the natural linewidth

Abstract

We demonstrate a nonlinear optical filter with ultranarrow bandwidth in cesium vapor. The optical filter operates on the 6S(1/2)→7P(3/2) transition at 455 nm. The single peak transmission at the 6S(1/2), F=4→7P(31/2), F'=5 transition is 9.7% with a bandwidth of 6.2 MHz, whereas at the 6S(1/2), F=3→7P(3/2), F'=2, 3 (cross-over) transition is 6.1% with a bandwidth of 3.9 MHz. The bandwidth approaching the natural linewidth is improved at least two orders of magnitude compared with conventional Faraday anomalous dispersion optical filters. This technique can also be applied to other alkali atoms.

Simultaneous Faraday filtering of the Mollow triplet sidebands with the Cs-D1 clock transition

“…An ideal point is given close to the atomic resonances when the absorption is low, but the dispersion still allows for a polarization rotation of π /2. Recently, these filters have demonstrated astonishing properties, such as narrow linewidths and reduced background212324, and enabled treating the problem as an optimization challenge25. An interesting feature used in the present experiment is that this filter shows the option to work as a double narrow-band pass filter with the two bands separated by the Cs-clock transition at around 10 GHz, as discussed above.…”

Ten years of active optical frequency standards

“…Active Faraday optical frequency standards [32] utilize Faraday atomic filters [33][34][35][36][37][38][39][40][41][42] as frequency references when working in bad-cavity regime. The output light frequency is determined by alkali atomic transition line of Faraday atomic filter and the output stimulated emission light power can be increased by adopting Ti: sapphire, dye and semiconductor materials as gain medium since the quantum reference of frequency standard and the stimulated emission of gain medium are spatially separated.…”

“…The Faraday atomic filters with narrow bandwidth have been studied in our group since 2011 [36][37][38][39][40][41][42]. The experimental setup of ultranarrow bandwidth Faraday atomic filter based on alkali atoms is shown in Fig.…”

Lasing of Cesium four-level active optical clock

“…In a three-level configuration [2,6], the pumping laser directly affects the frequency of clock transition. In order to greatly reduce the light shift of clock transition caused by pumping laser, an optical clock scheme in fourlevel configuration with Cesium atoms is proposed [7][8][9][10][11][12].…”