Characterisation of a Predictable Quantum Efficient Detector and Application for a Direct Calibration of a Reference Photometer

A predictable quantum efficient detector (PQED) based on induced-junction silicon photodiodes has been developed lately which can be used as a novel primary standard for optical power, thus, providing an alternative to cryogenic radiometers. Modeling and characterisation at a set of selected wavelengths have shown that the spectral responsivity of a PQED operated at room temperature (RT-PQED) can be predicted with an uncertainty at the level of 100 ppm. The implementation of the RT-PQED as a primary standard for radiometry, though, requires experimental validation by characterising its performance with respect to the relevant characteristics over the whole spectral range of applications. We present measurements investigating the angular, polarisation and bandwidth dependences of the RT-PQED. Moreover, the spectral irradiance responsivity of a reference photometer will be determined by a direct calibration against the RT-PQED using a wavelength tunable laser setup at PTB. The results are compared to those obtained via a conventional traceability route using a state-of-the-art transfer standard detector which is traceable to a cryogenic radiometer.