Scheme of an optical transistor based on phase modulation

We study the realization of the switching, routing and amplifying functions of an optical transistor by means of modulating the probe transmission signal and the four-wave mixing band gap signal by changing the relative phase and the nonlinear phase shift in an electromagnetically induced transparency medium based on an inverted Y-type four-level atomic system experimentally and theoretically. By changing the frequency detuning of relevant fields, we can change the nonlinear phase shift and correspondingly realize different functions. Through altering the incident angle of the dressing field, we can obtain different relative phases and realize further modulation for all-optical switches, routers and amplifiers. This scheme offers more flexible control parameters for the modulation of optical devices used in quantum information processing. (paper)