Frequency Reference for Atomic Transitions of Rb D-2-Line Based on the Effect of Selective Reflection

On an example of the D-2-line of the Rb atoms the work of the frequency reference of atomic transitions is demonstrated, based on the application of the spectrum of a selective reflectance (SR) from the boundary of atom vapors with the use of nano-cell (NC) with the thickness L similar to lambda/2, where lambda is the laser wavelength equal to 780 nm. When changing the thickness of the nano-cell near the thickness L similar to lambda/2, we observe the inversion of sign of the SR slope profile which is positive when L < lambda/2 and negative when L > lambda/2. In the case when the incidence angle of the laser beam on the surface of the nano-cell is close to the normal, in real-time it is possible to form the derivative of the SR which represents a resonance peak with similar to 35 MHz spectral linewidth and located at the atomic transition. The phenomenon of oscillation of the sign of slope while changing the nano-cell thickness from L similar to lambda/2 up to L similar to 3/2 lambda is demonstrated. The practical application of the SR is noted.