Optical trapping, Field enhancement and Laser cooling in photonic crystals.

We present a detailed study of the mode structure of inverse opal photonic crystal materials with an emphasis on their potential use in optical trapping and cooling. In particular, we analyze the modes corresponding to the upper and lower band edges of a high refractive index inverse opal, i.e., the so-called ;;air' and ;;dielectric' bands. In the dielectric band, we demonstrate optical intensity enhancements of two orders of magnitude which may facilitate nonlinear optical effects in the solid. In the air band, dipolar optical trapping potentials for cold atoms in the voids arise when these modes are excited by an external laser field. In addition, we discuss aspects of atom cooling through the polarization gradients provided by these modes. The results suggest that optical trapping and cooling may be achieved within a photonic crystal using a single laser source.