Radiation Damping in Atomic Photonic Crystals

The force exerted on a material by an incident beam of light is dependent upon the material’s velocity in the laboratory frame of reference. This velocity dependence is known to be difficult to measure, as it is proportional to the incident optical power multiplied by the ratio of the material velocity to the speed of light. Here we show that this typically tiny effect is greatly amplified in multilayer systems composed of resonantly absorbing atoms exhibiting ultranarrow photonic band gaps. The amplification effect for optically trapped ${}^{87}\mathrm{Rb}$ is shown to be as much as 3 orders of magnitude greater than for conventional photonic–band-gap materials. For a specific pulsed regime, damping remains observable without destroying the system and significant for material velocities of a few ${\mathrm{ms}}^{-1}$.

Figure 1

Normalized $x$ component of the force $\overrightarrow{F}$ as a function of detuning around resonance. The two panels show the force velocity-independent ($F_{(0)}^1$) and velocity-dependent ($F_{(1)}^1$) parts.

Figure 2

Normalized impulse $\Delta {\overrightarrow{P}}^{\prime }·\widehat{\mathit{x}}$ acquired from a 3-m-long Gaussian pulse impinging upon a multilayered atomic structure. The detuning ${\delta }_c$ between the pulse carrier frequency (${\omega }_c$) and atomic resonance (${\omega }_0$) is in units of ${\gamma }_e$. The inset shows the absorption $A=1-R-T$.