U of T theoretical physicist honored for work with light capture technology

Dr.  Sajeev John, professor of theoretical physics at the University of Toronto, has developed a technology to capture light in microchips and photocells.

It’s not exactly a lightning bolt in a bottle, but Professor of Theoretical Physics at the University of Toronto, Dr. Sajeev John’s life’s work is something close.

John, who this week was honored with a Herzberg Gold Medal from the Natural Sciences and Engineering Council of Canada, has spent much of his career developing a technology that captures light in a crystal and is getting ready to revolutionize green energy, medicine and possibly computer.

The technology of so-called photonic crystals – also known as the Photonic Band Gap technology – uses materials that are configured so that the microscopic wavelength of photons is contained in the crystal matrix long enough to extract more energy or to use the light in a way that electricity works in transistors and microchips.

This means that silicon solar cells designed in such a way can be as thin as a plastic film and potentially adhere to any surface.

“You can make it much thinner, by a factor of a hundred thinner, and absorb a lot more sunlight (than conventional solar cells),” John said. “So now silicon is becoming very light. And it’s so thin that it’s becoming flexible, you can bend it and coat it on a variety of surfaces, buildings, cars, even clothes. It extends the applicability of this type of solar capture beyond the traditional ones. areas.”

The promise of thin-film solar cells is not that far off, John said. He said he is working with partners in Europe and around the world to perfect a way to make the crystals based on his designs.

As the effects of climate change become more pronounced, John sees the solar cell applications of photonic crystals to collect solar energy as the most immediately vital, but the technology has other uses in medicine and computers.

In the case of the latter, John says that it should be possible to capture light on a silicon microchip – something that has not been possible before the development of photonic crystal.

“With this photonic crystal, you not only limit it, but you do it on a scale of the wavelength of light itself,” he said. Once such a chip has been perfected, it would be effectively powered by laser light – and literally work at the speed of light.

The technology has first been used in medicine for years for diagnostic procedures, but John hopes it can be used in an optical microchip that could perform medical laboratory work at the microscopic level, “a laboratory on a chip,” he said.

It would not exactly be like a Star Trek medical tricorder “Doctor McCoy waves it over a patient and it would be taking a sample from the body.”

But John noted that it would be smaller and it would let patients have all the work done in their family doctor’s office.

Mississauga resident John’s award of the Herzberg Gold Medal was announced on November 17th. The award comes with $ 1 million in funding, spread over five years, which John said will go to hiring and supporting young scientists, graduate students and others to join his team.

“It might mean going in some whole new directions,” he said. “It’s not tied to just one specific topic.”


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