The accurate metrological characterization of light sources and detectors is fundamental for many fields of application that satisfy social (lighting, human vision, industrial (telecommunications, new materials) and scientific (environmental monitoring, research basis). It is therefore essential to take care of the creation of the basic photometric unit of the International System of Units (SI), the Candela, and the derived photometric and radiometric units.
Our group carries out innovative research for the improvement of primary standard and for the characterization of detectors and sources also in response to the needs created by new lighting technologies, emerging quantum technologies and new knowledge on the physiology of human vision.
Among the activities we carry out we can highlight:
- The realization of photometric units starting from radiometric units according to an appropriate physiological model of the response of the human eye. Photometry is essential for the characterization of light sources used for illumination, signaling, displays and other applications where the light is intended for human observers;
- The validation of predictable photodetectors (PQEDs) as primary samples. These detectors are made up of photodiodes that allow measuring optical powers with uncertainties comparable to those of the cryogenic radiometer, which constitutes the state of the art in this field. The sector is an active partner in European projects that aim to validate these performances thanks to the dual photoelectric-radiometric operation of PQEDs;
- Research on the traceability of radiometric measurements from the classical to the quantum regime, with the development of tools and methodologies for the characterization of single photon sources and detectors operating in the first and third telecom windows (around 850 nm and 1550 nm respectively), of interest in classical and quantum communications, and the creation of new prototypes of single photon sources as radiometric standards;
- The development and characterization of superconducting single photon detectors, in particular Transition-edge sensors (TESs), in close collaboration with the ML1 sector, which deals with the fabrication of the devices. In addition to taking care of their development and characterization, the sector is involved in various experiments aimed at using TES for low luminous flux calibrations in quantum metrology experiments, for the search for dark photons with which the nature of cold dark matter is investigated and for the detection of single electrons in fossil neutrino experiments.