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Nb5N6 bolometer is a high sensitive terahertz detector at room temperature. The core part of traditional Nb5N6 bolometer is microbridge with a typical size of 3 μm × 12 μm. We have recently proposed a method using electron beam lithography (EBL) instead of UV lithography on fabrication of Nb5N6 micro bridge, which will reduce the size of the micro-bridge one to two orders of magnitude, the minimum...
We design a T-shape structure reflecting mirror covered a gold thin film on the high-resistivity silicon substrate (ρ=1000 Ω·Cm) for the detector array. The electric field distribution of the T-shape structure is simulated by using finite difference time domain (FDTD) solutions in the frequency range from 300 GHz to 400 GHz. The electric field can be gathered in the central area of the silicon substrate...
Terahertz (THz) direct detectors based on superconducting niobium nitride (NbN) hot electron bolometers (HEBs) with microwave (MW) injection have been studied. Compared to the thermal biasing method, the injected MW is used here to bias the HEB to the optimum point. MW can be expected to be used as the easy read out for the detecting array. The used NbN HEB has an excellent performance as heterodyne...
We present an antenna-coupled 1 × 64 Nb5N6 microbolometer array detectors for real-time terahertz (THz) imaging. The intrinsic average responsivity of the detectors in the array is 650 V/W, and the corresponding noise equivalent power (NEP) is 17 pW/√Hz. The array chip is combined with a low noise readout circuit with 64 channels. The array detector was preliminary used for THz source imaging, and...
A system to detect the terahertz (THz) pulse signals has been studied based on the superconducting NbN hot electron bolometer (HEB) detectors, which has the noise equivalent power (NEP) of 9×10−12 W/√Hz, together with a Fourier transform spectrometer (FTS). The detector has been driven by an easily adjustable microwave source to its best bias working point, and its output shown a linear relationship...
The efficiency is one of the most important parameter of single photon detector (SPD). The ideal SPD is expected to have 100% efficiency without false counts (always called dark counts). Improving the efficiency and reducing dark counts are interesting work for both scientific research and practical applications. Superconducting nanowire single photon detector (SNSPD) was intensively developed for...
Phase grating structure has the ability to converge light. We have introduced it to couple with superconducting nanowire single photon detector (SNSPD) to enhance its response for light. The effects of the coupling structure parameters on the enhancement have been studied systematically by FDTD method. Our numerical simulation show that the optical density arriving on nanowires of SNSPDs can be enhanced...
We have fabricated and characterized ultrathin NbTiN films with high Titanium (Ti) composition for applications of superconducting nanowire single photon detectors (SNSPD). An alloy with 47 wt. % Ti and 53 wt. % Nb as the target material is employed. NbTiN thin films with thicknesses ranging from 5 nm to 20 nm are grown onto MgO (100), Si (100) and $\hbox{SiO}_{\rm X}\hbox{-Si} $ substrates by DC...
We designed and fabricated Nb5N6 microbolometers integrated with five staircases square diffractive lens array (DLA) for THz detection. It gives us a method for designing diffractive lens to improve the coupling efficiency of the incident power into the Nb5N6 microbolometers. We measured the voltage response of the Nb5N6 microbolometer integrated with diffractive lens. We find it has 30 times larger...
An active imaging system has been constructed using a Cassegrain reflector with the diameter of 30 cm and a direct detector with the noise equivalent power of about 1.5×10−11 W/Hz1/2 at room temperature and 0.22 THz. It takes about 0.5 s to get 40×40 pixels and the special resolution is about 1.41 cm.
NbN thin films ( a few nm thick) are deposited on MgO substrates and patterned into meander lines to make single photon detectors at telecommunication wavebands of 1310 nm and 1550 nm. Typically the width of the meander line is 100 nm, and the detection area is 10?? 10 ??m2. The detector efficiency, dark count rate, time jitter, and response speed of the single photon detectors are discussed. Possible...
The optimization of the nanowire geometry of superconducting single photon detector is demonstrated in this paper. A typical setting of the detection area, 10 umtimes10 um, is adopted in this experiment. With 4 nm NbN films, the falling time of the response pulse is calculated, which implies the falling time increase a lot for narrow nanowire. At the same time, the falling time also increase a little...
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