Room‐temperature CO2laser 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.