Cs 728 nm excited state Faraday anomalous dispersion optical filter with indirect pump

We demonstrate a Cs excited state Faraday anomalous dispersion optical filter (ESFADOF) operating at 728 nm using a novel pump method, by which the pump beam and the probe beam in the ESFADOF realized here have no a common energy level. Using this method, the ESFADOF achieves a transmission of 2.39% with a bandwidth of 22.52 MHz, which can be applied to both laser frequency stabilization and future four-level active optical clocks. Under the 455 nm laser pump, in addition to 52D5/2, other states such as 72S1/2, 72P3/2, 62P3/2, 62P1/2 and 52D3/2 have also been populated effectively. Meanwhile, multiple wavelength filters exploiting atomic transitions to these states can be realized. •A Cs ESFADOF operating at 728 nm is realized using an indirect pump method.•The ESFADOF can be applied to both laser frequency stabilization and future four-level active optical clocks.•Multiple wavelength filters exploiting atomic transitions to these states can be realized.•This method can also be extended to other wavelengths of ESFADOF.