Study of EIT resonances in an anti-relaxation coated Rb vapor cell

We demonstrate---experimentally and theoretically---that resonances obtained in electromagnetically induced transparency (EIT) can be both bright and dark. The experiments are done using magnetic sublevels of a hyperfine transition in the D$_1$ line of $^{87}$Rb. The degeneracy of the sublevels is removed by having a magnetic field of value 27 G. The atoms are contained in a room-temperature vapor cell with anti-relaxation coating on the walls. Theoretical analysis based on a two-region model reproduces the experimental spectrum quite well. This ability to have both bright and dark resonances promises applications in sub- and super-luminal propagation of light, and sensitive magnetometry.Comment: 16 pages, 9 figure

SELECTIVE REFLECTION SPECTROSCOPY AT THE INTERFACE BETWEEN A CALCIUM FLUORIDE WINDOW AND Cs VAPOUR

International audienceA special vapour cell has been built, that allows the measurement of the atom-surface van der Waals interaction exerted by a CaF2 window at the interface with Cs vapour. Mechanical and thermal fragility of fluoride windows make common designs of vapour cells unpractical, so that we have developed an all-sapphire sealed cell with an internal CaF2 window. Although impurities were accidentally introduced when filling-up the prototype cell, leading to a line-broadening and shift, the selective reflection spectrum on the Cs D1 line (894 nm) makes apparent the weak van der Waals surface interaction. The uncertainties introduced by the effects of these impurities in the van der Waals measurement are nearly eliminated when comparing the selective reflection signal at the CaF2 interface of interest, and at a sapphire window of the same cell. The ratio of the interaction respectively exerted by a sapphire interface and a CaF2 interface is found to be 0.55 ± 0.25, in good agreement with the theoretical evaluation of ~0.67

Laser spectroscopy with nanometric gas cells : distance dependence of atom-surface interaction and collisions under confinement

The high sensitivity of Laser Spectroscopy has made possible the exploration of atomic resonances in newly designed "nanometric" gas cells, whose local thickness varies from 20nm to more than 1000 nm. Following the initial observation of the optical analogous of the coherent Dicke microwave narrowing, the newest prospects include the exploration of long-range atom surface van der Waals interaction with spatial resolution in an unprecedented range of distances, modification of atom dielectric resonant coupling under the influence of the coupling between the two neighbouring dielectric media, and even the possible modification of interatomic collisions processes under the effect of confinement

Experimental Investigation of Electromagnetically Induced Transparency in Selective Reflection Spectra

We have investigated electromagnetically induced transparency in the spectrum of selective reflection at the interface of Rb atom vapors and a dielectric nanocell window. A nanocell with atomic vapor column thicknesses ranging from 150 to 1200 nm, as well as a 50~$\mu$m thickness microcell were used. We have compared electromagnetically induced transparency observed for the cases of the selective reflection and transmission. It was demonstrated that for the thicknesses of below $\leq 1000$ nm selective reflection technique is more favorable. In contrast, for wider cells and microcells, using transmitted radiation as probe field is more effective.Comment: 9 pages, 4 figure

Observation of magnetically-induced transition intensity redistribution in the onset of the hyperfine Paschen-Back regime

The Zeeman effect is an important topic in atomic spectroscopy. The induced change in transition frequencies and amplitudes finds applications in the Earth-field-range magnetometry. At intermediate magnetic field amplitude $B\sim B_0 = A_\text{hfs}/\mu_B$, where $A_\text{hfs}$ is the magnetic dipole constant of the ground state, and $\mu_B$ is the Bohr magneton ($B_0\approx 1.7$ kG for Cs), the rigorous rule $\Delta F = 0, \pm1$ is affected by the coupling between magnetic sub-levels induced by the field. Transitions satisfying $\Delta F = \pm2$, referred to as magnetically-induced transitions, can be observed. Here, we show that a significant redistribution of the Cs $6\text{S}_{1/2}\rightarrow 6\text{P}_{3/2}$ magnetically-induced transition intensities occurs with increasing magnetic field. We observe that the strongest transition in the group $F_g=3\rightarrow F_e=5$ ($\sigma^+$ polarization) for $B<B_0$ cease to be the strongest for $B>3 B_0$. On the other hand, the strongest transition in the group $F_g=2\rightarrow F_e=4$ ($\sigma^-$ polarization) remains so for all our measurements with magnetic fields up to 9 kG. These results are in agreement with a theoretical model. The model predicts that similar observations can be made for all alkali metals, including Na, K and Rb atoms. Our findings are important for magnetometers utilizing the Zeeman effect above Earth field, following the rapid development of micro-machined vapor-cell-based sensors