Realising the candela based on electrical substitution and quantum standards
Combining two types of primary standard detectors – Predictable Quantum Efficient Detectors (PQED) and cryogenic electrical substitution radiometers (ESR) – is a promising way to deliver simplified, accurate and cost-effective traceability for optical power measurements. Packaging two standards together also creates a robust link to the revised SI, by measuring the fundamental constant ratio of the elementary charge divided by the Planck constant. Low availability and lack of experimental techniques to extract PQED internal quantum deficiency has, so far, prevented exploitation.
The project developed experimental techniques to make optical power measurements over a wide spectral and dynamic range, for an eventual self-calibrating ‘NMI-on-a-chip’. Models to predict internal quantum deficiency were improved; techniques developed to enable self-calibration of photodiodes, instrumentation and packaging developed; and metrological applications demonstrated. Take-up of technologies will be promoted to the photonics sector, and commercialisation of developed products is expected after a follow-up project. Self-calibrating photodiodes will enable measurements of optical power to unprecedented levels of accuracy and could enable remote operation.
This project builds on from EMRP project SIB57 NEWSTAR.