Fig. 1. Relevant energy-level and fine transitions of Cs atoms for (a) a 6S1/2-6P3/2-8S1/2 (852  nm+795  nm) ladder-type system (not to scale) and for (b) a 6S1/2-6P3/2-7S1/2 (852  nm+1470  nm) ladder-type system (not to scale). There are fewer decay channels from the Cs 7S1/2 state than that from the Cs 8S1/2 state, which may aid in the analysis of the cooling mechanism.

Fig. 2. (a) Schematic diagram of the laser beam configuration of the Cs TC-MOT and (b) the relevant energy levels and transitions. Four 852 nm CTBs (Ωge) couple the |g〉-|e〉 hyperfine transition, while two 1470 nm CTBs (Ωee′) couple the |e〉-|e′〉 hyperfine transition. σ± are specified with respect to the positive directions of the x, y, and z axis, and I is the direct current (DC) electric current of the anti-Helmholtz coils.

Fig. 3. The peak fluorescence intensities of Cs atoms trapped in the Cs TC-MOT as a function of the two-photon detuning δ1, the repumping beams’ total power is 2×2.0  mW, (a) with various 1470 nm CTBs’ power, while the 852 nm CTBs’ total power is 4×6.10  mW, and the single-photon detuning is Δ1=−12.5  MHz. The insets are false-color fluorescence images of the cold cloud for δ2=−36.6 and +28.4  MHz, respectively; (b) with different 852 nm CTBs’ power, while the 1470 nm CTBs’ total power is 2×20.0  mW, and Δ1=−12.5  MHz; (c) with various Δ1, while the 1470 nm CTBs’ total power is 2×20.0  mW, and the 852 nm CTBs’ total power is 4×6.10  mW. The vertical red lines in (a), (b), and (c) indicate δ2=0, the vertical blue lines in (a), (b), and (c) indicate δ2=+12  MHz, and the vertical gray lines in (a) and (b) indicate δ2=−12  MHz.