Figure 2
A single recorded spectrum. Transmission spectra of the sodium cell with the coupling laser turned on (blue) and turned off (red). The peaks due to enhanced transparency and dips due to enhanced absorption are clearly visible. Observed are two sets of features separated by the ground state splitting of sodium. The spectra are horizontal cuts from the density plots in Fig. 4 at zero detuning of the coupling laser. The background spectrum is obtained by averaging the transmission signals across all recorded detunings of the coupling laser. (a) Shows the recording for the D1-line. The probe power is 15 μW; the coupling laser power amounts to 440 mW. (b) The same recording for the D2-line. To note that the absorption is increased due to the higher oscillator strength of the D2-line. Probe power: 35 μW and coupling power of 530 mW.
