Sensitivity measurement of a 10.6-µm parametric upconverter

The sensitivity of a parametric upconverter for the detection of 10.6-µm radiation was measured. 10.6-µm radiation was mixed with the 1.06 µm beam of an Nd :YAG laser in properly oriented single-crystal proustite. The upconverted output at 0.967 µm was then detected by an S-1 photomultiplier tube. NEP of 1.1×10
^-9
W . s
^½
was measured.