Room-temperature CO₂ laser radiation detector

A novel microthermopile for CO₂ laser radiation detection with a fast response time has been fabricated for the first time. The microthermopile is fabricated by high-resolution e-beam lithography and isotropic plasma etching of the substrate resulting in free-standing hot junctions which are thermally isolated from the substrate. The good thermal isolation and small heat capacity of the hot junctions resulted in a responsivity of 60 V/W and a time constant of 20 μs. The device operates over the entire CO₂ laser wavelength range from 9.4 to 10.6 μm. Detailed measurements are presented for 10.6 μm operation.