Study on optical transition-edge sensors sensitive to a single photon
金属が低温で示す超伝導現象を応用した超伝導転移端センサを用いた超高感度の光検出器を開発しています。本研究で開発した光センサは高い検出効率を実現し、可視光から近赤外までの広帯域の光をとらえられます。さらに、光子を1個1個分光することが可能です。超伝導転移端センサは、単一光子の分光を高感度で実現するデバイスです。単一光子レベルでの分光計測が可能となることで、多色のバイオイメージング、光情報通信に必要な光子の計測など様々な分野での極限応用計測を可能とします。さらに、軽い暗黒物質探索への応用も目指します。超伝導転移端センサは1電子ボルト(eV)の信号に感度があることから、暗黒物質と電子の相互作用によって生成した信号を捉えることが期待されます。
We are developing optical transition edge sensors, which are based on the superconductivity phenomenon that metals exhibit at low temperatures. Our TESs achieves high detection efficiency and can capture a wide range of light from visible to near-infrared. They are capable of spectroscopic analysis of individual photons. TESs realize single photon spectroscopy with high sensitivity. The ability to measure spectroscopy at the single photon level enables extreme applications in a variety of fields, such as multi-color bio-imaging and photon measurement for optical information communication. We aim to apply TESs to dark matter search experiments. We also aim to apply this to light dark matter searches. Since transition-edge sensors are sensitive to signals at the electronvolt (eV) scale, they are expected to detect signals generated by interactions between dark matter and electrons.
本研究では、超伝導転移の特性を利用した非常に感度の高い温度計である超伝導転移端センサを用いて、超高感度の光検出器(左図)を実現しました。
In this study, we have realized an ultra-sensitive photodetector (left) using a superconducting transition edge sensor, which is an extremely sensitive thermometer that utilizes the properties of the superconducting transition.
By detecting the slight increase in temperature caused by a photon absorbed by a TES, the energy of the photon can be measured. When monochromatic light source is irradiated, the TES can count the number of photons absorbed simultaneously.
Fiber-coupled TES
(legacy setup)
Fiber-coupled TES
Device wafer
Cross sectional view of TES
左図は、パルスレーザーをセンサに照射して得られた光子数スペクトルです。今回、超伝導転移温度を従来の1/3にすることで、68 meV (at 0.8 eV)エネルギー分解能を達成しました。
The left figure shows the photon number spectrum obtained by irradiating the sensor with a pulsed laser. In this study, we achieved 68 meV (at 0.8 eV) energy resolution by lowering the critical temperature to one-third of the conventional value.