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/lambda, where lambda = 895 nm is the wavelength of laser radiation resonant with the D-1 line. The comparison of the parameters for two selected thicknesses L = lambda and lambda/2 has revealed an unusual behavior of the Faraday rotation signal: the spectrum of the Faraday rotation signal at L = lambda/2 = 448 nm is several times narrower than the spectrum of the signal at L = lambda, 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 = lambda/2 increases, whereas the amplitude of the signal at L =. 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.