Suppression of exciton-polariton light absorption in multiple quantum wellBragg structures

A dramatic suppression of the absorption of light by exciton polaritons is observed after resonant excitation of the polaritonic modes in a multiple q uantum well Bragg structure. Time-resolved reflectivity measurements confir m that this is due to the formation of a dominant superradiant polariton mo de created by the light-induced coupling of excitons in different quantum w ells that suppress absorption. The stability of the superradiant mode is de monstrated at high excitation powers and at temperatures of up to 180 K.