Detection of 3.4 THz radiation from a quantum cascade laser using a microbolometer infrared camera

Abstract

The THz wavelengths cover the frequency range of 0.1-10 THz or 30-3000 μm wavelength band. Currently, detection of THz radiation is carried out using either antenna-coupled semiconductor detectors or superconducting bolometers. Imaging of objects using these detection schemes requires complex scanning mechanisms which limits the applications involving real time imaging. For imaging applications it is desirable to employ focal plane arrays (FPAs) which leads to more compact systems. The FPAs based on photon detectors commonly used in infrared require cooling which becomes stringent as the detection extends to THz wavelengths. On the other hand, microbolometer FPAs using thermal detectors based on temperature change due to infrared absorption have a broad wavelength response and can be operated at room temperature. The advances of microbolometer technology allow real time imaging in the 7-13 μm wavelength range with relatively high sensitivity. However, their ability to detect THz radiation is relatively unknown. In this paper, imaging of a 3.4 THz (88 μm) laser beam using an uncooled microbolometer camera is described.