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The operation frequency of superconducting integrated THz receivers can be enhanced by replacing the commonly used elementary niobium with niobium nitride. This work presents the technology development of high-quality niobium nitride thin films and superconductor-insulator-superconductor multilayers along with the simulation and realization of high-frequency circuits for a superconducting integrated THz receiver using niobium nitride electrodes.

To date optically pumped gas lasers are used as local oscillators in heterodyne receivers at frequencies above 2 THz. In this report we describe the design and performance of a compact 1-5 THz gas laser which is operated in a heterodyne receiver aboard of SOFIA, the Stratospheric Observatory for Infrared Astronomy.

Terahertz quantum cascade lasers have been investigated with respect to their performance as a local oscillator in a heterodyne receiver. The beam profile has been measured and transformed in to a close to Gaussian profile resulting in a good matching between the field patterns of the quantum cascade laser and the antenna of a superconducting hot electron bolometric mixer. Noise temperature measurements with the hot electron bolometer and a 2.5 THz quantum cascade laser yielded the same result as with a gas laser as local oscillator. (C) 2005 Optical Society of America.