Photon switch in a quantum well by quantum interference in interband transitions

We propose a scheme for a photon switch based on quantum interference in interband transitions in an asymmetric semiconductor coupled double quantum well structure. It is shown that, due to the existence of tunneling induced quantum interference, a weak resonant probe field, in the ultraviolet or visible spectral region, can pass through this structure with little absorption. A second coupling field can switch off the probe laser by destroying the destructive interference at the resonant probe frequency. The photon switch can be achieved easily with relatively small pulse intensity (104 W/cm2) because of a large dipole moment length (10−8 m) in the interband transition.