Atomic vapor quantum counter: Narrow-band infrared upconverter

A novel device for the upconversion of narrow-band infra-red (IR) radiation in the 1.5-20-µm spectral region is described. The atomic-vapor quantum counter (AVQC) takes advantage of the efficient incoherent upconversion of narrow-band IR radiation in an optically excited atomic vapor. In a 300 K background and a 2π-sr field of view, a D^*is projected that is two orders of magnitude greater than that of conventional semiconductor devices. The device offers the extremely high Q´s (>10⁵) associated with heterodyne detection while simultaneously offering a broad tuning range and an unlimited collection aperture. The anticipated performance characteristics of the AVQC are discussed, Experimental results in sodium and potassium have demonstrated the high Q and the tunability of the device. Electric field tuning of the wavelength response to CO2laser wavelengths spanning 23 cm^-1has been accomplished. Applications of the AVQC involving the detection of low level laser radiation and molecular emission are discussed.