Quantum optics in a photonic band gap material

Corin Adlard, Sarben Sarkar

S. John

Summary form only given. Photonic band gap (PBG) materials are a new class of dielectrics which represent a major new frontier in quantum, nonlinear, and classical optics. They also represent a new technology platform for the optical networking industry. Unlike semiconductors which facilitate the coherent propagation of electrons, PBG materials execute their novel functions through the coherent localization of photons. When a PBG material is doped with impurity atoms (or other two-level systems) which have an electronic transition that lies within the gap, spontaneous emission of light from the atom is inhibited. Instead, the photon forms a bound state to the atom. This has dramatic consequences for collective light emission from a large number of atoms and for the interaction of such atoms with an external laser field. I describe the design of an all optical micro-transistor based on collective switching of two-level atoms near a photonic band edge, by an external laser field. I discuss tunable PBG materials whose band structure can be modulated by means of an external field. This effect enables the steering of light in a manner similar to the steering of electrons by an electric field in a semiconductor.

Kazuaki Sakoda

Sajeev John

Photonic band gap (PBG) materials are a new class of dielectric materials which exhibit a complete three-dimensional gap to electromagnetic wave propagation. These materials facilitate two novel and fundamental optical principles, namely (i) the coherent localization of light and (ii) the control and inhibition of spontaneous emission of light from atoms and molecules.

Marian Florescu A, Sajeev John

We describe all-optical transistor action in photonic band gap materials doped with active atoms. In the presence of a photonic band gap (PBG) material, a coherent laser beam with the frequency slightly detuned from the resonant atomic transition frequency can drive a collection of two-level atoms to an almost totally inverted state, a phenomenon strictly forbidden in ordinary vacuum. By changing the laser field intensity in the neighborhood of a threshold value, it is possible to drive the atomic system through a transition from states in which the atoms populate preferentially the ground level to almost totally inverted states. In this process, the atomic system switches from a passive medium (highly absorptive) to a active medium (highly amplifying). The switching action in a PBG material is not associated with operating near a narrow cavity resonance with conventional trade-off between switching time and switching threshold intensity. Rather it is associated with an abrupt discontinuity in the engineered broad band electromagnetic density of states of the PBG material. We demonstrate all-optical transistor action in PBG materials by analyzing the absorption spectrum of a second probe laser beam and we show that the probe beam experience a substantial differential gain by slight intensity modulations in the control laser field.