Low-noise Si transferring detector for correlated photon absolute source

Abstract

The space radiometric benchmark enables in-orbit traceable to SI system, calibrates in-orbit loads, improves data consistency across different space radiometric remote sensing missions, and facilitates long-term high-precision monitoring of global climate and environment. The transferring detector becomes an absolute power detector by quantum optical radiation measurement in the self-calibration mode, and is used to measure solar radiation in the observation mode. Si photodiode is used as transferring detector in the visible band, which requires high-precision radiometric detection at the photon level. Therefore, Si photodiode and its amplifying circuit need to have low noise. To expand the detection dynamic range of Si photodiode under low radiation condition, the noise sources of Si photodiode and its amplifier circuit are analyzed, and cooling of Si photodiode is proposed to reduce the noise. Vacuum cryogenic experiment was conducted to study the temperature characteristics of Si photodiode at 223K to 263K, and the temperature control design requirements were obtained. A sealed package Si photodiode based on two-stages TEC was developed, and a high-precision temperature control circuit with -40 °C ± 0.01 °C was designed. The shunt resistance of the cooled Si photodiode at -40°C was tested to be 8.5 TΩ, and the dark current was 1.2 fA. A wide dynamic range low-light-level irradiance source with adjustable radiation intensity is used to test the cooled Si photodiode with a low-noise transimpedance amplifier, the measurement signal-to-noise ratio was 1158 when the photocurrent was about 1pA.