June 16 (UPI) -- Researchers in Russia have successfully grown optical chips in a Petri dish. The breakthrough could pave the way for a variety of smaller and more precise optical technologies.
Optical chips are made of tiny lasers and waveguides. Lasers inside the optical chips currently deployed by the modern photonics industry rely on infrared emissions.
In order to build a more compact optical chip, engineers at IMTO University set out to pair microlasers and waveguides that use light in the visible spectrum. Visible light features smaller wavelengths.
"The size of a chip depends on the wavelength of its emission," Sergey Makarov, chief researcher with ITMO's department of physics and engineering, said in a news release.
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Microlasers produce light emissions, while waveguides direct the emissions. But the silicon waveguides found in infrared optical chips are unable to direct light emissions in the visible range.
"They transmit the signal no further than several micrometers," said Ivan Sinev, senior researcher in the physics and engineering department. "For an optical chip, we need to transmit along tens of micrometers with a high localization, so that the waveguide would have a very small diameter and the light would go sufficiently far through it."
Previous attempts to replace silicon with silver have yielded poor results. For the new optical chip, researchers turned to gallium phosphide for the waveguide, a material better suited to propagating visible light.
Typically, waveguides are carved using nanolithography. The research team at ITMO used solution chemistry to successfully grow both the optical chip's light source and waveguide in a Petri dish -- a much cheaper and more efficient method.
Scientists were able to synthesize optical chips roughly three times smaller than current infrared chips. The team of engineers described the new technology in a new paper, published this week in the journal ACS Nano.
The new chip could be used to create more compact biosensors or serve as the building blocks of the next generation of quantum computers, which use photons instead of electrons to store, process and transfer information.
"The chip's important property is its ability to tune the emission color from green to red by using a very simple procedure: an anionic exchange between perovskite and hydrogen halides vapor," said Anatoly Pushkarev, senior researcher at ITMO.
"Importantly, you can change the emission color after the chip's production, and this process is reversible. This could be useful for the devices that have to transmit many optical signals at different wavelengths," Pushkarev said. "For example, you can create several lasers for such a device, connect them to a single waveguide, and use it for transmitting several signals of different colors at once."
Researchers were also able to combine two of the new optical chips using a tiny perovskite antenna, which receives the signal traveling through the waveguide
"We added a nanoantenna at the other end of our waveguide," said Pavel Trofimov, doctoral student in the department of physics and engineering. "So now, we have a light source, a waveguide, and a nanoantenna that emits light when pumped by the microlaser's emission."
"We added another waveguide to it: as a result, the emission from a single laser went into two waveguides," Trofimov said. "At the same time, the nanoantenna did not just connect these elements into a single system, but also converted part of the green light into the red spectrum."
