Abstract: A normally opaque waveguide interacting with a drop-filter cavity can be switched to a transparent state when the drop filter is also coupled to a dipole. This dipole induced transparency may be obtained even when the vacuum Rabi frequency of the dipole is much less than the cavity decay rate. The condition for transparency is a large Purcell factor. Dipole induced transparency can be used in quantum repeaters for long distance quantum communication.

Abstract: A normally opaque waveguide interacting with a drop-filter cavity can be switched to a transparent state when the drop filter is also coupled to a dipole. This dipole induced transparency may be obtained even when the vacuum Rabi frequency of the dipole is much less than the cavity decay rate. The condition for transparency is a large Purcell factor. Dipole induced transparency can be used in quantum repeaters for long distance quantum communication.

Abstract: Optical microcavities based on two dimensional arrays of holes defined in photonic crystals are optimized for maximum Q factors and minimum mode volume. They can also be used for strong coupling between the cavity field and an atom trapped within a defect of the photonic crystals, or for tunable filters if the holes are filled with electro-optical polymers. In one embodiment the Q factor of a cavity is increased by elongation of a plurality of holes in at least one row in a predetermined direction. Modal structures of microcavities, as well as quality factors, mode volumes, symmetry properties and radiation patterns of localized defect modes as a function of the slab thickness and parameters of photonic crystal and defects are illustrated.