Figure 1

Scheme of the experimental setup. We use a thin Cs cell ($4.5\times 4.5\times 0.5$ mm${}^3$) of a microfabricated array [4].Reuse & Permissions

Figure 2

Measured cell absorption profile at $120{}^{\circ }\mathrm{C}$ with partially resolved ground state hyperfine structure (black line), shot-noise-limited sensitivity in conventional operation modus (open circles) and light-narrowed operation (filled triangles). After optimization of all parameters a sensitivity of $42\mathrm{fT}/\sqrt{\mathrm{Hz}}$ is achieved in the light-narrowed mode (black star).Reuse & Permissions

Figure 3

Cell absorption curve as addition of the four buffer-gas broadened Cs $D_1$ hyperfine transitions fitted to the experimentally determined absorption profile of Fig. 2, using Lorentz profiles due to the dominant buffer-gas broadening. Tuning the narrow-band laser from $F=4$ (conventional mode) to $F=3$ (LN mode) is accompanied by changing the relative pumping ratio ($F=3:F=4$) approximately from 1:5 to 9:1.Reuse & Permissions

Figure 4

Pumping scheme and calculated populations (in percent) of the $\mathrm{Cs}$ ground state in (a) conventional-mode operation (pumping on $F=4$) and (b) in LN configuration (pumping on $F=3$ with 50-fold overall pumping rate). Laser pumping excitation is sketched by black arrows, whose thicknesses indicate pumping strength. The steady-state solutions of the population rate equations for all 16 ground state sublevels, given by Lang et al. [22] are used. This model assumes depopulation pumping mechanism (quenching de-excitation equally probable to all ground state sublevels). It was extended to include a fixed relative pumping ratio between the hyperfine ground state level transitions determined by the overlap of the partially resolved ground state absorption profile at the actual laser pumping frequency (as depicted in Fig. 3). Perfectly circularly polarized light is assumed and effects of repumping by $B_1$ as well as the ${45}^{\circ }$ orientation of $B_0$ in the $M_x$ regime are not included.Reuse & Permissions