Light Pulse Slowing Down up to 0.025 cm/s by Photorefractive Two-Wave Coupling

It is shown experimentally and theoretically that photorefractive wave coupling can be used for dramatic ($\lesssim 0.025\mathrm{c}\mathrm{m}/\mathrm{s}$) deceleration of light pulses whose width is larger than (or comparable with) the nonlinear response time. This classical nonlinear scheme exhibits similarities with the technique based on the quantum effect of electromagnetically induced transparency. The main distinctive feature of our scheme is amplification of the delayed output pulse. Advantages of the novel technique and its prospects for manipulation with light photons are discussed.

Figure 1

A schematic of a pulse amplification experiment; the parallel lines inside the crystal depict the grating fringes.

Figure 2

Experimental time dependences of the normalized input and output intensities of the signal (curves 1 and 2, respectively) for ${\mathrm{B}\mathrm{a}\mathrm{T}\mathrm{i}\mathrm{O}}_3$ (a) and ${\mathrm{S}\mathrm{n}}_2{\mathrm{P}}_2{\mathrm{S}}_6$ (b) crystals.

Figure 3

The output signal shape for $t_0/\tau =1$ and $\Gamma d=0$, $8$, and $16$; the corresponding peak amplification factors are $1$, $\approx 2\times {10}^2$, and $3\times {10}^5$.

Figure 4

The ratios $\Delta t/\tau$ (a) and $w_d/\tau$ (b) versus $t_0/\tau$; the squares are experimental data for ${\mathrm{B}\mathrm{a}\mathrm{T}\mathrm{i}\mathrm{O}}_3$ and the theoretical lines are plotted for $\Gamma d=8$.

Figure 5

The calculated normalized output intensity for $\Gamma d=8$, and $t_0/\tau =0.02$ [curve (a)], $0.08$ (b), and $0.25$ (c).