Photonic band gap with coherently controlled defeat induced by a nanoscale structure

Photonics band gap properties will be changed dramatically if there is a defect at the center of the photonic crystal. We theoretically proposed a nanoscale structure, i.e., n-doped asymmetric quantum wells, coherently controlled by an infrared laser. Due to the quantum interference in the conduction intersubband transitions, the refractive index could be monitored at some specific wavelength. This structure is applied at the center of the photonic crystal or grating waveguide as a coherently controlled defect . We also investigated the reflection, transmission or delay time of this one-dimensional photonic band gap at various wavelengths while the defect is adjusted by an infrared laser beam. It is believed that the structure could be used in the devices for the optical pulse reshaping, dispersion control, and wavelength filter or used as a distributed Bragg grating reflector for the laser mode tuning. Therefore it might have great applications in the optic communication or information processing.