In this work, a 230 GHz all-NbN superconductor-insulator-superconductor (SIS) mixer was designed and analyzed. The NbN/AlN/NbN tunnel junctions (with an energy gap of 5.7 meV) and NbN/MgO/NbN tuning circuits were utilized. Full-height waveguides and bow-tie waveguide probes were adopted. The signal coupling circuit was designed and optimized to be transmissible to the given band. The quantum mixing characteristics of the all-NbN mixers were optimized with different-size SIS junctions. The mixer with a junction diameter of 1 μm achieves a conversion gain close to 0 dB and a noise temperature close to 40 K. The proposed design and analysis will provide technical support for the recovery and upgrade of the heterodyne receiver for the Leighton Chajnantor Telescope (LCT).
The Leighton Chajnantor Telescope (LCT) is an international cooperation project among Caltech, University of Concepcion (UdeC), and Shanghai Normal University (ShNU), which aims to relocate the Caltech Submillimeter Observatory (CSO) telescope from Mauna Kea, Hawaii to the Chajnantor plateau in northern Chile. ShNU has the opportunity to upgrade a 345/650 GHz dual-color SIS receiver, which was made by Caltech, for the LCT. In order to technically support this dual-color receiver, 345/650 GHz SIS mixers were designed and optimized based on the existing superconducting technology in the lab of ShNU. Within the proposed frequency range, both mixers show good sensitivity and gain characteristics. The optimized mixers show a DSB noise temperature of 24K and a conversion gain of 4.2dB at 345GHz, and a DSB noise temperature of 61K and a conversion gain of -2.9dB at 650GHz, respectively. Detailed design and results will be provided.
The Leighton Chajnantor Telescope (LCT) project, sponsored by Shanghai Normal University in collaboration with Caltech and the University of Concepción, is seeking to relocate the Caltech Submillimeter Observatory (CSO)[1] from Mauna Kea, Hawaii to Llano de Chajnantor Observatory on the Chajnantor Plateau in Chile. The LCT will be equipped with a new 345-GHz band heterodyne array receiver of 3×3 beams and quantum-limited sensitivity. Based on superconducting Nb/Al-AlOx/Nb tunnel junction (SIS) mixers, we have developed a compact 1×3 array as one unit of the new heterodyne array receiver. Detailed design and measurement results will be presented.
In this theoretical work, we report on voltage-controllable hybridization of electromagnetic modes arising from strong
interaction between graphene plasmons and molecular vibrations. Compared with the strong light-matter interaction
platforms based on noble metals, graphene offers much tighter plasmonic field confinement thus smaller effective mode
volume and higher quality-factor due to longer carrier relaxation time in midinfrared regime, leading to Rabi splitting
and hybridized polaritonic modes at 3 orders of magnitude lower molecular densities. Electrostatically tunable carrier
density in graphene allows for dynamic control over the interaction strength. In addition, the flat dispersion band arising
from the deep confinement of the polaritonic modes gives rise to the omni-directional excitation. Our approach is
promising for practical implementations in infrared sensing and detection.
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