Monash University in Melbourne and RMIT Universities have collaborated to develop a photonic integrated circuit. This creates data superhighways and revolutionizes the connectivity of optical chips. It also replaces bulky 3D-optics by a thin, wafer-thin slice of silicon.

The journal Nature Photonics published this development. It has the potential to accelerate the global advancement in artificial intelligence. This discovery also offers real-world applications, such as:

Photonics, the science of light, is changing how we live. Photonic chips can turn bulky utility programs into tiny chips that are as small as a fingernail.

Dr. Mike Xu, Monash University’s Department of Electrical and Computer Systems Engineering and currently at Beijing University of Posts and Telecommunications. Professor Arthur Lowery, Monash University‚Äôs Department of Electrical and Computer Systems Engineering and Dr. Andy Boes conducted this research while at RMIT.

Professor Arnan Mitchell, Dr. Guanghui Ren designed the chip to be ready for the experimental demonstration.

Monash University ARC Laureate Fellow, Professor Arthur Lowery, said that this discovery complements the earlier discovery by Dr. Bill Corcoran of Monash University. In 2020, RMIT and Monash University partnered to develop an optical microcomb chip. This chip can squeeze three times as much traffic through one optical fiber. It is regarded as the fastest internet speed using a single fingernail-sized device.

The optical microcomb chip created multiple lanes on the superhighway. Now the self-calibrating chips has built the ramps and bridges connecting them all, allowing for greater data movement.

Professor Lowery explains, “We have demonstrated a selfcalibrating programmable filter chip that uses photonic filters to self-calibrate,”

Self-calibration is important because it makes tunable photosnic integrated circuits more useful in the real life. Examples include optical communications systems that switch signals between destinations based on color, very fast computations (correlators), scientific instrumentation to perform chemical and biological analyses, and even astronomy.

“Electronics saw similar advances in radio filter stability using digital techniques. That led to many mobiles being allowed to share the same spectrum chunk; our optical chips have the same architectures but can operate on signals with high terahertz bandwidths.

This breakthrough was three years in the making.

Future internet-dependent technologies, such as self-driving cars and remote controlled mining, will need faster and more bandwidth. Bandwidth increases are not about increasing the optical fibers that our internet travels through. It’s also about creating compact switches in many colors and going multiple directions so that data can be sent down many different channels simultaneously.

“This research is a major breakthrough. Our photonic technology has advanced enough that complex systems can be integrated onto a single chip. InPAC Professor Arnan Mitchell says that the idea of a device having an on-chip reference system that allows its components to work together is a technological breakthrough. This will enable us to quickly reconfigure the optical networks that carry our internet in order to resolve bottleneck issues.

Photonic circuits can manipulate and route optical information channels, but they also have some computational capabilities, such as the ability to search for patterns. Pattern searching is essential for many applications, including medical diagnosis, autonomous vehicles and internet security.

The chips can be reprogrammed quickly and reliably, allowing new search tasks to become programmed quickly and accurately. However, this manufacturing needs to be precise to the degree of a tiny wavelength of light (nanometers), which is currently difficult and extremely expensive–self-calibration overcomes this problem.

The research involved integrating all of the optical functions into a device that could be “plugged-in” to existing infrastructure.

Professor Lowery, ARC Laureate Fellow, says that the solution is to calibrate chips after manufacturing and to tune them up in effective by using an on chip reference. We use the beauty and necessity of causality, effect after cause. This means that the optical delays in the paths through the chip can be determined uniquely from the intensity versus wavelength. This is much easier than measuring precise time delays. We calibrated our chip with a strong reference path. This allows us to dial up the desired switching function or spectral response.

This is an essential step in making photonic chips practical. Researchers could instead of searching for a setting like a radio tuner, they could tune the chip in one stage, allowing the switch of data streams quickly and reliably from one destination to the next.

Reliable tuning of photonic chip opens up many new applications, including optical correlators which can almost instantly find patterns in data streams such as images. This is something the group has also been working towards.

“It becomes increasingly difficult to get more parts of smaller equipment into small chips. This makes it more difficult to get them to work together and achieve the same speed and function as when they were larger. This was overcome by designing a chip smart enough to calibrate itself to ensure that all components work at the same speed,” Dr. Andy Boes, University of Adelaide.