Low noise NbN hot electron bolometer mixer at 4.3?THz

We have studied the sensitivity of a superconducting NbN hot electron bolometer mixer integrated with a spiral antenna at 4.3?THz. Using hot/cold blackbody loads and a beam splitter all in vacuum, we measured a double sideband receiver noise temperature of 1300?K at the optimum local oscillator (LO) power of 330?nW, which is about 12 times the quantum noise (h?/2kB). Our result indicates that there is no sign of degradation of the mixing process at the superterahertz frequencies. Moreover, a measurement method is introduced which allows us for an accurate determination of the sensitivity despite LO power fluctuations.Kavli Institute of NanoscienceApplied Science

Direct detection effect in small volume hot electron bolometer mixers

We measure the direct detection effect in a small volume (0.15??m×1??m×3.5?nm) quasioptical NbN phonon cooled hot electron bolometer mixer at 1.6?THz. We find that the small signal sensitivity of the receiver is underestimated by 35% due to the direct detection effect and that the optimal operating point is shifted to higher bias voltages when using calibration loads of 300?K and 77?K. Using a 200?GHz bandpass filter at 4.2?K the direct detection effect virtually disappears. This has important implications for the calibration procedure of these receivers in real telescope systems.Kavli Institute of NanoscienceApplied Science

THz communication system based on a THz Quantum Cascade Laser and a Hot Electron Bolometer

We present the experimental study of the direct emission - detection system based on the THz Quantum Cascade Laser as a source and Hot Electron Bolometer (HEB) detector - in view of its application as an optical communication system. We show that the system can efficiently transmit the QCL Terahertz pulses. We estimate the maximal modulation speed of the system to be about several GHz and show that it is limited only by the QCL pulse power supply, detector amplifier and connection line/wires parameters

THz communication system based on a THz Quantum Cascade Laser and a Hot Electron Bolometer

We present the experimental study of the direct emission - detection system based on the THz Quantum Cascade Laser as a source and Hot Electron Bolometer (HEB) detector - in view of its application as an optical communication system. We show that the system can efficiently transmit the QCL Terahertz pulses. We estimate the maximal modulation speed of the system to be about several GHz and show that it is limited only by the QCL pulse power supply, detector amplifier and connection line/wires parameters

Direct Detection Effect in Hot Electron Bolometer Mixers

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