Cs 5D_ 5/2–6F 728nm Laser Spectroscopy with Single Pumping Laser

The sub-Doppler absorption laser spectroscopy at 728 nm transition from the 5D_ 5/2 state to the 6F state of cesium with linewidth near 10 MHz is first experimentally performed with indirect pumping from the ground state 6S_1/2 to the state 7P_3/2 by a 455.5 nm diode laser. Using a 455.5 nm diode laser as an indirect pump laser, several excited states will be populated due to spontaneous decay from the 7P state. We first implement the sub-Doppler absorption laser spectroscopy at 728 nm from the 5D_ 5/2 state to the 6F state when Cs atoms within thermal glass cell decay to the 5D_ 5/2 state. Due to velocity transfer effect, the hyperfine structure of 5D_ 5/2 shows a mixed and complicated pattern but very clear structure when the 455.5 nm pumping laser is counter-propagating (or co-propagating) with the 728 nm probing laser.