Ultradispersive adaptive prism based on a coherently prepared atomic medium

We have experimentally demonstrated an ultra-dispersive optical prism made from a coherently driven Rb atomic vapor. The prism possesses spectral angular dispersion that is 6 orders of magnitude higher than that of a prism made of optical glass; such angular dispersion allows one to spatially resolve light beams with different frequencies separated by a few kilohertz. The prism operates near the resonant frequency of atomic vapor and its dispersion is optically controlled by a coherent driving field.

Figure 1

(a) Refraction of light by the prism. (b) Configuration of the probe and control laser beams inside the cell of Rb vapor. One can see that our setup can be viewed as an ultradispersive prism. (c) Simplified scheme of the energy levels of Rb atoms.

Figure 2

Experimental setup: ECDL, external cavity diode laser; PBS, polarizing beam splitter; GP, parallel glass plate; $\lambda /2$ and $\lambda /4$, retardation wave plates, PSD, position-sensitive detector; DSO, the digital storage oscilloscope; CCD, linear CCD camera.

Figure 3

(a) Spatial distributions of the control (1) and probe (2) fields at the input of the atomic cell (we have no magnification of the optical beams). The probe is shifted to the right with respect to the control field. (b) Spatial distributions of the probe fields (2) and ($2^{\prime }$) at the distance of 2.3 m after passing the atomic cell for different detunings corresponding to the maximal angles of deviation.

Figure 4

Curve 1: Dependence of the deflection angle of the probe beam on detuning for the probe beam initially shifted to the right (a) and to the left (b) with respect to the control beam. Curve 2: Dependence of the probe field transmission versus detuning.

Figure 5

Calculated dependence of the deflection angle of the probe beam on detuning for the probe beam vs. two-photon detuning.