Rubidium dimer destruction by a diode laser

We observed rubidium dimer destruction by excitation of rubidium vapor with diode laser light tuned across the Rb ${\mathrm{D}}_2$ resonance line in a 2400 GHz tuning interval. The destruction was measured for rubidium atom concentrations in the $\left(1\text{–}9\right)\times {10}^{16}{\mathrm{cm}}^{-3}$ range, pump beam power up to 43 mW, and with a 5 Torr of the helium buffer gas. We discuss the physical mechanisms involved and specify the molecular pathways which may effectively lead to the observed dimer destruction.

Figure 1

Experimental setup. AM: amplifier; FM: folder mirrors; PD: photodiodes; BS: beam splitters; S: beam stopper.

Figure 2

The optical density $\left(kL\right)$ vs the equilibrium concentration of the ground-state rubidium molecules. The probe laser was tuned at 830 nm. The pump laser was off.

Figure 3

The modulation of the probe beam transmission induced by the pump laser. The pump laser is positioned in the red wing of the Rb ${\mathrm{D}}_2$ first resonance line, whereas the probe laser was set at 685 nm. The rubidium atom concentration was $1.34\times {10}^{16}{\mathrm{cm}}^{-3}$.

Figure 4

The destruction efficiency vs the pump laser output power. The pump frequency detuning from the center of Rb ${\mathrm{D}}_2$ line was $-531\mathrm{GHz}$ with the maximum output power of 31 mW. The probe laser was tuned to 830 nm and the rubidium atom concentration was $2.8\times {10}^{16}{\mathrm{cm}}^{-3}$.

Figure 5

The destruction efficiency vs the pump frequency detuning for pump laser power of 43 mW and probe laser at 830 nm. Full circles: experimental results for ${\mathrm{N}}_{\mathrm{Rb}}=2.45\times {10}^{16}{\mathrm{cm}}^{-3}$; hollow circles: experimental results for ${\mathrm{N}}_{\mathrm{Rb}}=3.64\times {10}^{16}{\mathrm{cm}}^{-3}$. Lines: fit results $L=6\mathrm{cm}$, $K=0.1\mathrm{cm}$, and $L=7\mathrm{cm}$, $K=0.06\mathrm{cm}$ (20% fit error), respectively.

Figure 6

The ${\mathrm{Rb}}_2$ adiabatic potential curves stemming from rubidium $5s+5p$ molecular asymptote taken from Ref. 26.