Demonstration of a dual-mode Si detector as a self-calibrating device at room temperature.

We demonstrate the use of a dual-mode detector for determining the internal quantum deficiency of a silicon photodiode without the use of an external reference. This is achieved by combining two different principles for measuring optical power in one device, where the photodiode is used as absorber for both thermal and photon detection. Thermal detection is obtained by the same principle as for an electrical substitution radiometer (ESR), with a type A measurement uncertainty of 0.34 % in unstabilized room temperature. The optical power measured in thermal mode was around 3 % ± 0.5 % higher than what was measured in photocurrent mode. Heat transfer simulations revealed a difference of up to 2.2 % between optical and electrical heating, and based on these simulations we give recommendations for improvements of the detector thermal design.