Seebeck infrared photodetectors for high power CO2 laser beam monitoring

Generic Seebeck infrared photodetectors for high power CW and pulsed CO2 laser beam monitoring in industrial and medical applications are presented here. The theoretical background of Seebeck or thermo-electric detectors in doped semiconductors is briefly denoted. Different operation modes such as the intensity, energy and power operation regime of the Seebeck photodetector depending on the temporal characteristics of the incident laser beam are presented as well. The main attention is paid to the design parameters and geometrical structures related to high power profilometry. We will also explain how one can control the detectable power and intensity levels by means of the doping concentration, absorption layer thickness, pixel geometry, metallic shielding and cooling mechanisms of the detector. The wide dynamic range of design possibilities of Seebeck infrared photodetectors allows us to measure CO2 laser powers and beam profiles from W to multi-kW in CW and to GW/cm2 in the nano to picosecond range. Finally, an overview is given of experimental results on multi-pixel arrays for multi-kW CO2 laser beams.