Photovoltaic indium antimonide detectors have been operated at temperatures ≤77 K with sufficiently low background radiation levels that Johnson noise limited performance is realized. Under such conditions the noise equivalent power (NEP) is completely determined by the detector operating temperature, resistance, and quantum efficiency. Optimization of these parameters in the manufacture of commercially available detectors has led to 5-μm NEP’s as low as 10-15 W. The particular preamplifier is critical to the achievement of Johnson noise limited operation and is described in detail.
Donald N. B. Hall, Richard S. Aikens, Richard Joyce, and Thomas W. McCurnin, "Johnson Noise Limited Operation of Photovoltaic InSb Detectors," Appl. Opt. 14, 450-453 (1975)