Electrical measurement capabilities of the cryogenic dual-mode optical power detector

The dual-mode optical power detector combines two primary measurement methods into one device - photocurrent and thermal detection. The combination of these two methods can be exploited in a self-calibration procedure, where the internal losses of the photodiode absorber are determined using the thermal mode as a reference. Another advantage of the dual-mode detector, which this work focuses on, is that it provides a direct link between radiometric primary measurement methods and the new SI, by extracting the fundamental constants ratio e/hc. This makes the dual-mode detector self-assured, and also serves as a validation of the two primary methods, through a cryogenic high-accuracy comparison on one device. In this work, we present the current electrical measurement capabilities of the dual-mode setup at 40 K and 60 K, to give an indication of the achievable uncertainty level of the e/hc measurement.