COHERENT EXCITON LASING IN ZNSE/ZNCDSE QUANTUM-WELLS

A new mechanism for exciton lasing in ZnSe/ZnCdSe quantum wells is proposed. Lasing, occurring below the lowest exciton line, may be associated with a BCS-like condensed (coherent) exciton state. This state is most stable at low temperatures for densities in the transition region separating the exciton Bose gas and the coherent exciton state. Calculations show the gain region to lie below the exciton line and to be separated from the absorption regime by a transparency region of width, for example, about 80 meV for a 90 Å ZnSe/Zn0.75Cd0.25Se quantum well. Experimental observation of the transparency region using differential spectroscopy would confirm this picture.© 1995 American Institute of Physics.