1671-7694/2014/101204(4) 101204-1 © 2014 Chinese Optics Letters

Faraday anomalous dispersion optical filter (FADOF) has many advantages: high transmission, ultranarrow bandwidth[1], and high noise rejection[2]. Hence, FADOF is used in many fields where signal-to-noise ratio (SNR) is critical, such as free-space optical communication[3], lidar[4–7], and the generation of narrowband quantum light[8]. And optical filter can be used for optical frequen-cy stabilization when adopted as a frequency selection component in laser system[9–13]. So far, FADOF has been widely studied both theoretically and experimentally with several elements, including rubidium (Rb)[14–21], po-tassium[22,23], cesium[24,25], sodium[26,27], and calcium[28]. However, the bandwidth of FADOF is generally limited at gigahertz level due to Doppler broadening. Thus, an excited state atomic filter based on circula