Features of faraday rotation in cs atomic vapor in a cell thinner than the wavelength of light

Features of the effect of Faraday rotation (the rotation of the radiation polarization plane) in a magnetic field of the D ₁ line in Cs atomic vapor in a nanocell with the thickness L varying in the range of 80–900 nm have been analyzed. The key parameter is the ratio L/λ, where λ = 895 nm is the wavelength of laser radiation resonant with the D ₁ line. The comparison of the parameters for two selected thicknesses L = λ and λ/2 has revealed an unusual behavior of the Faraday rotation signal: the spectrum of the Faraday rotation signal at L = λ/2 = 448 nm is several times narrower than the spectrum of the signal at L = λ, whereas its amplitude is larger by a factor of about 3. These differences become more dramatic with an increase in the power of the laser: the amplitude of the Faraday rotation signal at L = λ/2 increases, whereas the amplitude of the signal at L = λ almost vanishes. Such dependences on L are absent in centimeter-length cells. They are inherent only in nanocells. In spite of a small thickness, L = 448 nm, the Faraday rotation signal is certainly detected at magnetic fields ≥0.4 G, which ensures its application. At thicknesses L < 150 nm, the Faraday rotation signal exhibits “redshift,” which is manifestation of the van der Waals effect. The developed theoretical model describes the experiment well.     

Study of the Interaction of Potassium Atoms with the Sapphire Surface with the Use of an Ultrathin Spectroscopic Cell

JETP Letters - The effect of the dielectric surface on the 39K D1 line (Fg = 1, 2 → Fe = 1, 2 transitions) at nanometer distances has been experimentally studied for the first time. A...     

KCs Molecular Bands in the Visible Region

Optics and Spectroscopy - We measured light absorption of potassium and cesium mixed vapors at temperatures 360–660°C in the visible spectral region 380–780 nm. By comparison with...     

Strongest Magnetically Induced Transitions in Alkali Metal Atoms

JETP Letters - Atomic transitions in alkali metals that have zero probability in the absence of a magnetic field but have large probabilities in the presence of a magnetic field are called...     

Canonical systems

In this paper, we study canonical systems and pose the problem of constructing a quasihomogeneous canonical system, i.e., the canonical system whose spectral problem has the same solution as that of the spectral problem of some homogeneous canonical system. We present a rational algorithm for constructing a quasihomogeneous canonical systems.     

A Modified Method of Faraday Rotation for Investigation of Atomic Lines of Rubidium and Potassium in Ultrathin Cells

Optics and Spectroscopy - A nanocell filled with atomic vapors of rubidium and potassium was used to develop a modified method of Faraday rotation. The formed lines are characterized by a spectral...     

Selective reflection of laser radiation from submicron layers of Rb and Cs atomic vapors: Applications in atomic spectroscopy

We studied selective reflection (SR) of laser radiation from a window of a nanocell with thickness L ~ λ_1,2/2 filled with Rb and Cs atoms, where λ₁ = 780 nm and λ₂ = 852 nm are the wavelengths resonant with the D₂ laser lines for Rb and Cs, respectively. It is demonstrated that the negative derivative of the SR signal profile for L > λ/2 changes to the positive one for L < λ/2. It is shown that the real-time formation of the SR signal profile derivative (SRD) with the spectral width 30–40 MHz and located at the atomic transition is, in particular, a convenient frequency marker of D₂ transitions in Rb and Cs. The amplitudes of SRD signals are proportional to the atomic transition probabilities. A comparison with the known saturated absorption (SA) method demonstrated a number of advantages, such as the absence of cross-over resonances in the SRD spectrum, the simplicity of realization, a low required power, etc. An SRD frequency marker also operates in the presence of the Ne buffer gas at a pressure of 6 Torr, which allowed us to determine the Ne–Rb collisional broadening, whereas the SA method is already inapplicable at buffer gas pressures above 0.1 Torr. The realization simplicity makes the SRD method a convenient tool for atomic spectroscopy. Our theoretical model well describes the SRD signal.     

Faraday Effect in Rubidium Atomic Layers Thinner than 100 nm

Journal of Experimental and Theoretical Physics - The interaction of rubidium atoms with sapphire cell windows at an interwindow distance L = 40–100 nm is studied. For studies, we used the...     

Selective Reflection of Potassium Vapor Nanolayers in a Magnetic Field

The selective reflection of laser radiation from the interface between a dielectric window and the atomic vapors confined in a nanocell of thickness L ≈ 350 nm is used to develop effective Doppler-broadening- free spectroscopy of potassium atoms. A small atomic line width and a relation between the signal intensity and the transition probability allowed us to resolve four lines of atomic transitions responsible for the D1 lines of the ³⁹K and ⁴¹K isotopes. Two groups containing four atomic transitions form in an applied magnetic field upon pumping by radiation with circular polarization σ⁺ or σ^–. Different intensities (probabilities) of transitions for the σ⁺ and σ^– excitations are detected in magnetic field B₀ ≈ A _hfs /μ_B ≈ 165 G (A _hfs is the magnetic dipole constant for the ground state and μ_B is the Bohr magneton). A substantially different situation is observed at B ? B₀, since high symmetry appears for the two groups formed by radiation with circular polarization σ⁺ or σ^–. Each group is the mirror image of the other group with respect to the frequency of the 4²S_1/2–4²P_1/2 transition, which additionally proves the occurrence of the complete Paschen–Back regime of the hyperfine structure at B ≈ 2.5 kG. A developed theoretical model well reproduces the experimental results. Possible practical applications are described. The results obtained can also be applied to the D₁ lines of ⁸⁷Rb and ²³Na.     

Selective reflection spectroscopy at the interface between a calcium fluoride window and Cs vapour

A 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 impractical, so that we have developed an all-sapphire sealed cell with an internal CaF₂ window. Although some impurities have remained when filling up the prototype cell, leading to line broadening and a shift, the selective reflection spectrum of 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 interactions 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. PACS 34.35.+a; 42.62.Fi; 42.70.Km