LIGHT CONTROL OF OPTICAL INTERSUBBAND ABSORPTION AND AMPLIFICATION INA QUANTUM-WELL INSIDE A CAVITY

We give a local-field calculation of the dynamic response of a single quantum Well (QW) inside a cavity pumped by a strong light beam. The s tarting paint oi our theory is the microscopic Maxwell-Lorentz equatio n combined with light-induced nonlinear current densities associated w ith intersubband transitions in the QW system, The frequency-and space -dependent current densities are derived from the density-matrix forma lism in a nonperturbative manner, Assuming only the electromagnetic co upling from the pump beam to the probe beam is important, we solve the wave equation exactly for both the pump and probe fields. In turn we determine the probe absorption coefficient of the QW structure. For a GaAs/Al0.33Ga0.67As QW placed between vacuum and a GaAs/AlAs distribut ed Bragg reflector followed ed by a GaAs prism. we calculate the probe absorption spectra for different parameters such as the pump frequenc y, the incident intensity of the pump field, and the cavity quality. O ur results shaw that the optical absorption and amplification for the probe field are strongly dependent of these parameters. It is also dem onstrated that it is of importance to take into account the dynamic sc reening effect for the pump field in the calculation of the probe spec tra.