1. Introduction: In high speed PIN and metal-semiconductor-metal (MSM) optical detectors, the speed of operation is limited by the sweep out and hence transit time of the optically generated carriers to contacts, with the transit time being determined by the electron and hole drift velocity in response to the electric field. By contrast, the collective excitation of an electronic medium may transfer energy with much higher velocity and overcome the charge transport limitations. The collective properties of electrons have been the subject of great interest …