3.4 THz heterodyne receiver using a hot electron bolometer and a distributed feedback quantum cascade laser

Abstract

We report a heterodyne receiver using a superconducting NbN hot electron bolometer ͑HEB͒ integrated with a tight winding spiral antenna as mixer and a distributed feedback ͑DFB͒ terahertz quantum cascade laser ͑QCL͒ operating at 3.42 THz as local oscillator. The aim is to demonstrate the readiness of both devices for the detection of OH lines at 3.5 THz in a real instrument. We show that the improved single-spot beam of the terahertz QCL can easily pump the HEB mixer. We measured a double sideband receiver noise temperature of 2100 K at the optimum local oscillator power of 290 nW. This noise temperature can be further reduced to 1100 K if we correct the loss due to the use of an uncoated lens, and the losses of the window and the air. Therefore, the combination of a HEB and such a DFB QCL can in principle be used to detect an OH line at 3.5 THz. However, a high input power of several watts, which is needed to operate the QCL in a liquid-helium cryostat, poses a big challenge to the receiver stability.

Low-voltage terahertz quantum-cascade lasers based on LO-phonon-assisted interminiband transitions

“…The QCLs exhibit lasing over a broad range of frequencies from 2.91 to 3.21 THz. Using single-plasmon waveguides, pulsed operation up to 114 K and CW operation up to 65 K has been achieved.Introduction: Terahertz (THz) quantum-cascade lasers (QCLs) have received a great deal of attention since they may be used as compact radiation sources for THz imaging and as local oscillators for THz heterodyne detection of trace gases [1][2][3]. The main problem of THz QCLs is their limited operation to cryogenic temperatures, quite frequently even well below liquid nitrogen temperatures, i.e.…”

Development of superconducting mixers for THz astronomy

“…In addition, we have also participated in the efforts of Netherland Institute for Space Research (SRON) and Delft University of Technology (TUDelft) on the development of superconducting HEB mixers around 5 THz and the integration of THz superconducting HEB mixers with THz quantum cascade lasers (QCLs). The measured noise performances are all summarized in Figure 2 [27][28][29][30][31][32]. Note that low frequency results were measured earlier with no specific optimization of the measurement setup.…”

Analysis of NbN Hot Electron Bolometer Receiver Noise Temperatures Above 2 THz With a Quantum Noise Model

“…The entire IF chain has a gain of about 80 dB and a noise temperature of 7 K. At 1.9, 2.5 and 4.3 THz an optically pumped FIR laser is employed as LO. At 2.8 and 3.5 THz, quantum cascade lasers are used [8], [9]. Fig.…”