Success Story: Harnessing starlight on a chip

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Harnessing starlight on a chip helps NRC scientists search for life on other planets

Researchers at the National Research Council of Canada (NRC) have packed starlight into a silicon-on-insulator photonic chip to probe the atmospheres of planets around other stars.

The silicon chip-based technology that makes ultrafast internet speeds possible may now benefit astronomical research, particularly in one fast-growing research area—the search for life on Earth-like exoplanets, which are planets that lie outside Earth’s solar system. Traditionally, such research would call for ever-larger astronomical instruments at the next generation of giant telescopes, but building them consumes vast amounts of money and time. So the pressure is on to come up with new solutions while pushing the boundaries of science and research.

It is not the first time that a photonic chip is used for astronomy, but this particular chip is definitely a first.

Enter a disruptive approach to that dilemma : the NRC’s photonic silicon chip technology, developed by the NRC’s Advanced Electronics and Photonics Research Centre in collaboration with the Herzberg Astronomy and Astrophysics Research Centre. Each chip has a specific purpose, for example, to find a certain set of gases on exoplanets when they pass in front of their host stars. This means that future astronomical instruments could contain many chips for different types of astronomy.

“Chips can also be designed and made in weeks or months at a relatively low cost,” says Ross Cheriton, Research Associate at the NRC’s Advanced Electronics and Photonics Research Centre. “And they can sometimes do things better than larger instruments because they’re more stable.”

With silicon-on-insulator photonics chips, light must be squeezed into waveguides nearly 100 times smaller than a human hair. But when light from stars enters the Earth’s atmosphere, it passes through several layers of turbulent air that blur images taken by telescopes on the ground. These disturbances can be corrected using an adaptive optics system. And so NRC scientists have recently commissioned the Research, Experiment and Validation of Adaptive Optics with a Legacy Telescope (REVOLT) system on the 1.2-metre McKellar Telescope.

“This technology corrects the distorted starlight, allowing telescopes to create images focused to the fundamental limit of their optics,” says Kate Jackson, Adaptive Optics Scientist at the Herzberg Astronomy and Astrophysics Research Centre. “It significantly improves the amount of light transferred into the photonic chips.”

REVOLT has a specially designed fibre injection unit to hold the position of the corrected star image stable on the end of a very small fibre, which transfers the light from REVOLT to the chip. Harnessing light from Betelgeuse, the brightest red star in the night sky and located 1,350 light years from Earth, the REVOLT test bed has injected starlight into a photonic waveguide on a chip that is over 5 trillion times smaller than the 1.2-metre telescope opening!

With the initial field test of this new chip technology successfully completed in real operating conditions for a professional-grade telescope, the next steps are being planned. Future work will focus on advancing the technology so it can detect signs of life marked by oxygen, carbon dioxide, methane or other gases in the atmospheres of planets outside our own solar system. The test demonstrates that there is a bright future for astronomical instruments with integrated photonics chips.

“The next frontier is to do large-scale surveys of these exoplanets in faraway star systems and search for signs of life,” adds Ross Cheriton. “This is a giant leap toward discovering other planets like ours and understanding our place in the universe.”

To that end, he is working with Herzberg Astronomy and Astrophysics project manager Adam Densmore to build an advanced version of the chip for use on REVOLT starting this fall.

“The next design will exploit one of the main benefits of integrated optics technology—the ability to array many devices on a single chip,” he says. “This will expand the instrument’s capability to detect several gas targets simultaneously.”

The NRC is also working with astronomers from the University of Toronto and Queen's University in Belfast to identify the most important gases to target and to determine requirements for the instrument.

The NRC’s internationally renowned REVOLT team includes engineers and scientists specializing in adaptive optics, software, high-precision opto-mechanics and electronics.

“This collaboration is a fantastic example where two areas of excellence at the NRC—photonics and astronomical instrumentation—can be leveraged to push the state of the art in science,” says Jean-Pierre Véran, Lead Adaptive Optics Scientist at the Herzberg Astronomy and Astrophysics Research Centre. “Indeed, the collaboration through this prototyping exercise is the first step toward providing the Canadian astronomical community with unique capabilities to carry out their scientific research.”

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