Discovery of a novel source of light

Professor Robert Boyd and his PhD student Samuel Lemieux are standing behind a table on which photonics research equipment is installed.

Professor Robert Boyd with Dr. Maria V. Chekhova (Max Planck Institute for the Science of Light, Germany), postdoctoral fellows Enno Giese and Robert Fickler, and PhD student Samuel Lemieux

Department of Physics

Over the years, Professor Boyd's name has become a synonym of research excellence at the University of Ottawa. This year again his laboratory stood out through an outstanding discovery a novel source of light for which the brightness is solely known from the laws of physics.

This newly discovered light source can be used directly as a standard to measure the sensitivity of a detector, without the need for any other reference. In order to achieve this result, Prof. Boyd and his team based their standard on the spontaneous generation of photon pairs, which is triggered by vacuum fluctuations. Quantum mechanics predicts that even in the absence of light (the vacuum), there remains minute fluctuations in the electromagnetic field. In this regard, they used the laws of quantum mechanics to predict the amplitude of those vacuum fluctuations, and thus infer the intensity of light at the output of their source. The light from their source is produced by shining an intense laser beam into a crystal with specific properties. The coupling of this laser with the vacuum fluctuations leads to the generation of the photon pairs. This coupling has a different strength depending on the color of the light being generated. In that sense, they used the spectrum of the vacuum fluctuations themselves as a reference for the brightness of the light.

The brightness of most sources of light in our daily lives, such as lightbulbs and computer monitors, must be calibrated. Any calibration procedure ultimately relies on primary standards, which can be based on a single agreed-upon artifact, or far preferably, on the laws of physics.  This is why primary standards based on the laws of physics are needed, rather than artifact-based standards. Prof. Boyd’s new standard will allow the dissemination and enhance the accuracy of current optical calibration procedures. Ultimately, this could lead to more efficient and safer lightbulbs and lasers. The researchers are hoping to develop methods to gauge the performance and safety of these devices to ensure that they can be trusted and used everywhere in the world

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