Slowing Down of Light in Photorefractive Crystals with Beam Intensity Coupling Reduced to Zero

A considerable deceleration of light pulses in crystals with nearly compensated space-charge field proves that the strong dispersion of dynamic photorefractive gratings in the vicinity of Bragg resonance is of primary importance for light slowing down.

Figure 1

Schematic of pulse propagation through a photorefractive crystal in the presence of a coherent pump wave.

Figure 2

Schematic of the experimental setup with photorefractive crystal (PRC), electro-optic modulator (EOM), beam splitter (BS), mirror (M), piezoelectrically driven mirror (PM), photodiode (PD), signal generators (SG1 and SG2), high voltage amplifier (HVA), and lock-in amplifier. The arrow near the sample indicates the positive direction of the spontaneous polarization; double arrows show the polarization of the light waves.

Figure 3

Experimental dependences of sample transmission $T$ (a),(c) and variation of propagation constant $\Delta k$ (b),(d) of a weak signal wave on frequency detuning of the signal wave.

Figure 4

Time delay of the output pulse maximum (a) and output pulse duration (b) as a function of input pulse duration; $I_p=1\mathrm{W}/{\mathrm{c}\mathrm{m}}^2$, grating spacing $\Lambda =1.8\mu \mathrm{m}$.

Figure 5

Two-beam coupling gain spectrum for CdTe:Ge.