The world's first self-calibrated photonic chip: Exchange for superhighway optical data

Conceptual diagram of a self-calibrating integrated broadband PIC. Credit: Xingyuan Xu et al, Nature Photonics (2022). DOI: 10.1038/s41566-022-01020-z

Research led by Monash and RMIT University in Melbourne has found a way to create advanced photonic integrated circuits that build bridges between data superhighways, revolutionizing the connectivity of today’s optical chips and replacing bulky 3D optics with thin slices of silicon wafers.

This development, published in the journal Nature Photonicshas the ability to accelerate the global advancement of artificial intelligence and offers significant real-world applications such as:

• Safer driverless cars capable of instantly interpreting their surroundings
• Enable AI to diagnose medical conditions faster
• Makes natural language processing faster for apps like Google Homes, Alexa, and Siri
• Smaller switch to reconfigure the optical network that brings our internet to get the data we need faster

Whether it’s turning on the TV or keeping the satellites on track, photonics (the science of light) is changing the way we live. Photonic chips can turn large bench-sized utility processing capabilities into fingernail-sized chips.

Dr. Mike Xu from Monash University’s Department of Electrical and Computer Systems Engineering and now at Beijing Post and Telecommunication University, Professor Arthur Lowery from Monash University’s Department of Electrical and Computer Systems Engineering, and Dr. Andy Boes, who did this research while at RMIT.

Professor Arnan Mitchell and Dr. Guanghui Ren engineered the chip so that it was ready for experimental demonstration.

The project’s lead researcher, Professor Arthur Lowery from Monash University ARC Laureate, said the breakthrough complements previous findings from Dr. Bill Corcoran of Monash University, who partnered with RMIT in 2020, developed a new optical microcomb chip that can triple the traffic. of the entire NBN via a single optical fiber, which is considered the world’s fastest internet speed from a single chip the size of a fingernail.

Optical microcomb chip builds multiple superhighway lanes; now self-calibrating chips have created ramps and on and off bridges that connect everything and allow for greater data movement.

“We have demonstrated a self-programmable photonic filter chip, which features a signal processing core and an integrated reference path for self-calibration,” explains Professor Lowery.

“Self-calibration is very important because it makes tunable photonic integrated circuits useful in the real world; applications include optical communication systems that redirect signals to destinations based on their color, very fast similarity calculations (correlators), scientific instrumentation for chemical or biological analysis, and even astronomy.

“Electronics is seeing a similar improvement in radio filter stability using digital techniques, which means that multiple phones can share the same chunk of spectrum; our optical chips have a similar architecture, but can operate on signals with a terahertz bandwidth.”

This breakthrough has been made for three years.

New internet-dependent technologies such as self-driving cars, remotely controlled mining, and medical equipment will require faster and greater bandwidth in the future. Increasing bandwidth isn’t just about increasing the optical fiber through which our internet travels, it’s about providing a compact switch with multiple colors, going in multiple directions, so data can be sent across multiple channels at once.

“This research is a major breakthrough—our photonic technology is now advanced enough that truly complex systems can be integrated on a single chip. The idea that a device can have an on-chip reference system that allows all of its components to work as a single unit is a technological breakthrough that allows us to solve the problem of internet bottlenecks by reconfiguring the optical network that carries our internet rapidly to get data where it is needed most,” said Professor Arnan Mitchell of InPAC.

Photonic circuits are capable of manipulating and routing optical information channels, but they can also provide some computational capabilities, for example, searching for patterns. Pattern search is essential for many applications: medical diagnosis, autonomous vehicles, internet security, threat identification and search algorithms.

Fast and reliable chip reprogramming allows new search tasks to be programmed quickly and accurately. However, these manufactures must be precise at the level of small wavelengths of light (nanometers), which is currently difficult and very expensive—calibration alone solves this problem.

The main challenge of this research is to integrate all the optical functions into a device that can be “plugged” into the existing infrastructure.

“Our solution was to calibrate the chips after manufacturing, to tune them into effect using an on-chip reference, rather than by using external equipment,” said Professor Lowery, ARC Laureate Fellow. “We used the beauty of causality, effect following cause, which determines that the optical delay of the path through the chip can be uniquely inferred from intensity versus wavelength, which is much easier to measure than exact time delay. We’ve added a robust reference path to our chip. and calibrate it. This gives us all the necessary settings for the desired ‘dial up’ and switching function or spectral response.”

This method is an important step towards making photonic chips practically useful. Instead of looking for a setup, similar to tuning an old radio, the researchers were able to tune the chip in one step, enabling fast and reliable switching of data streams from one destination to another.

The reliable tuning of photonic chips opens up many other applications, such as optical correlators, which can almost instantly find data patterns in data streams, such as images—something the group is also working on.

“As we integrate more and more bench-sized devices onto fingernail-sized chips, it becomes increasingly difficult to get them all to work together to achieve the speed and functionality they did when they were bigger. We overcame this challenge by creating a chip that was smart enough to calibrate itself. itself so that all components can work at the speed they need simultaneously,” said Dr. Andy Boes from the University of Adelaide.

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Generating radio signals using light

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Further information:
Xingyuan Xu et al, self-calibrating programmable photonic integrated circuit, Nature Photonics (2022). DOI: 10.1038/s41566-022-01020-z

Provided by Monash . University

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