Development of Submillimeter-Wave SIS Photon Detectors

利用超导隧道结的亚毫米波直接探测器的研制。超导亚毫米波探测器具有比低温测辐射热计更好的性能，适合于实现二维阵列。通过将工作温度降低到超导体临界温度的1/10以下，可以大幅度地抑制漏电流，实现高灵敏度的亚毫米波光子探测器。一种是入射光子的能量大于超导能隙。在此方案中，我们已经实现了远红外光子探测器。量子效率是一个有待解决的问题。另一种方案适用于能量低于差距能量的光子，其通常被称为视频检测器。该方案可以成功地实现宽带、高灵敏度的直接探测器，其性能可与工作在1.5K的测辐射热计相媲美。并联双结（PCTJ）已成功地应用于这种探测器。使用分布式结（DJ）阵列进行进一步的改进。在不久的将来，使用超导直接探测器的亚毫米波相机将被实现。

Development of submillimeter-wave direct detectors using superconducting tunnel junctions. The superconducting submillimeter-wave detectors are capable to realize better perfoamance than cryogenic bolometers and is suitable for realizing two dimesional array. By decreasing operating temperature less than 1/10 of the critical temperature of the superconductors, leakage current can be supressed dramatically and high sensitivity submillimeter-wave photon detector is to be realized.We used two schemes for its rdevelopment. One applies to incoming photon whose energy is larger than the superconducting energy gap. We have realized far-infrared photon detectors in this scheme. Quantumn efficiency is a problem to be solved. Another scheme is applicable for photons whose energy is lower than the gap energy, which is usually addressed as video detectors. For this scheme we could successfully realize wide band and high sensitivity direct detectors whose performance is comparable to bolometers operating at 1.5K.Parallel Connected Twin Junction (PCTJ) have been successfully applied for this detectors. Further improvement is performed using Distributed Junction (DJ) arrays. In near future submillimeter-wave camera using the superconducting direct detectors will be realized.