The current position：Research < Atomic Optical Filter
In optical communication, especially spatial optical communication, the background light can have a serious impact on communication quality. Therefore, optical filter is necessary. However, interference filter usually has a wide transmission spectrum of light and may have a bad performance under some conditions. Meanwhile, the frequency of laser may have a Doppler frequency shift when the laser source or receiver is moving, so it's best for the filter to be continuously tunable. Thus, we aimed at the research on atomic optical filter.
Atomic optical filters are based on the quantum properties of atomic energy levels, and realized with the magneto birefringence effect of atomic gas. Atomic optical filters are based on the quantum properties of atomic energy levels, and realized with the magneto birefringence effect of atomic gas. It is used to obtain ultra-narrow band optical filtering, achieving band pass of approximately 1 GHz, linewidth of atomic transitions. Kinds of atomic optical filters have been realized in various elements, such as potassium (770nm), rubidium (422nm, 780nm), cesium (455nm, 459nm, 852nm), calcium (423nm) and strontium (461nm).
Atomic optical filters have been widely used in laser communication, laser radar, solar observation and laser frequency stabilization. These filters can block background light beyond the transmission spectrum effectively and improved the noise-resisting capacity significantly. Today CREAM group focuses on realizing atomic optical filters of different wavelengths with different atoms, and hope to produce practical filters with better performances.
 Longfei Yin, Bin Luo, Anhong Dang, and Hong Guo, “An atomic optical filter working at 1.5 μm based on internal frequency stabilized laser pumping,” Opt. Express 22 (7), 7416-7421 (2014).  Longfei Yin, Bin Luo, Zhongjie Chen, Lei Zhong, and Hong Guo, “Excited state Faraday anomalous dispersion optical filters based on indirect laser pumping,” Opt. Lett. 39 (4), 842-844 (2014).