Electromagnetically induced transparency (EIT) effect has been studied using an extremely thin cell (ETC) with the thickness of an Rb vapor column of the order of light wavelength λ(780nm) and varying in the range of 0.5λ–2.5λ . Λ-systems on the D2 line of Rb85 and Rb87 have been studied experimentally. Along with EIT resonance, we study the peculiarities of velocity-selective optical pumping/saturation (VSOP) resonances, which accompany the EIT resonance and, as a rule, are spectrally broader. It is demonstrated that size-conditioned strongly anisotropic contribution of atoms with different velocities in an ETC causes several dramatic differences of the EIT and VSOP resonances formation in the ETC as compared with an ordinary 1–10cm long cell. Particularly, in the case of the ETC, the EIT linewidth and contrast dramatically depend on the coupling laser detuning from the exact atomic transition. A theoretical model taking into account the peculiarities of transmission spectra when L=nλ and L=(2n+1)λ/2 (n is an integer) has been developed. The experimental transmission spectra are well described by the theoretical model developed. The possibility of EIT resonance formation when atomic column thickness is of the order of L=0.5λ and less is theoretically predicted
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"EIT resonance can occurs in -system with a two long-lived states and one excited state coupled by two laser fields (so called coupling and probe lasers). From the application point of view it is important to reduce dimensions of the cell which are containing atomic vapor of metal where an EIT resonance is formed, while keeping resonance parameters good (such as narrow line-width and contrast)    . "
[Show abstract][Hide abstract] ABSTRACT: Comparison of absorption and fluorescence in a nano-cell containing Rb vapor with other Rb nano-cells with addition of neon gas is presented. It is shown that the effect of collapse and revival of Dicke-type narrowing occurs for Rb nanocells containing N2 as buffer gas under 6 and 20 Torr pressure for the thickness L = λ /2 and L = where λ is the resonant λ, laser wavelength 794 nm (D1 line). Particularly for 6 Torr the line-width of the transmission spectrum for the thickness L =λ/2 is 2 times narrower than that for L = λ. For an ordinary Rb cell with L = 0.1 - 10 cm with addition of buffer gas, the velocity selective optical pumping/saturation (VSOP) resonances in saturated absorption spectra are fully suppressed when the buffer gas pressure > 0.5 Torr. A spectacular difference is that for L = λ, VSOP resonances located at the atomic transitions are still observable even when Ne pressure is ≥ 6 Torr. Narrowband fluorescence spectra of a nano-cell with L = λ/2 can be used as a convenient tool for online buffer gas pressure monitoring for the conditions when ordinary pressure gauges are unusable. Comparison of electromagnetically induced transparency (EIT) effect in a nano-cell filled with pure (without a buffer gas) Rb with another nano-cell, where buffer gas nitrogen is added, is presented. The use of N2 gas inside Rb nano-cells strongly extends the range of coupling laser detunings in which it is still possible to form EIT resonance.
[Show abstract][Hide abstract] ABSTRACT: The electromagnetically induced transparency (EIT) on the atomic D
1 line of rubidium is studied using a nanometric-thin cell with atomic vapor column length in the range of L=400–800nm. It is shown that the reduction of the cell thickness by four orders as compared with an ordinary cm-size cell
still allows to form an EIT resonance for L=λ=794nm with the contrast of up to 40%. Further reduction of thickness to L=λ/2 leads to significant reduction of EIT contrast, verifying that the key parameter for EIT in wavelength-scale-thickness
cells is not the value of L itself but L/λ ratio. Remarkable distinctions of EIT formation in nanometric-thin and ordinary cells are demonstrated. Well-resolved splitting
of the EIT resonance in a magnetic field for L=λ can be used for magnetometry with nanometric spatial resolution. The presented theoretical model well describes the observed
Full-text · Article · Jan 2011 · Applied Physics B
[Show abstract][Hide abstract] ABSTRACT: We report observation of a narrow (sub-natural) and high-contrast resonance of increased absorption ("bright" resonance) in Rb cell with Ne buffer gas under previously unexplored experimental conditions for coupling and probe radiation configuration. The coupling laser stabilized frequency is detuned by ~ 3 GHz from 5S1/2, Fg=3 --> 5P3/2, Fe=2,3,4 transitions, while the probe laser frequency is scanned across these transitions. We believe the bright resonance formation, occurring when the probe laser frequency is blue-shifted from the coupling frequency by a value of the ground state hyperfine splitting, is caused predominantly by a 2-photon absorption of the probe radiation 5S1/2, Fg=2 --> 5S1/2, Fg=3 with 5P3/2 as an intermediate state. We also report and interpret splitting of the bright resonance into 6 well resolved and contrast components in moderate magnetic fields (B ~ 10 - 250 G).