Posted in | News | Optics and Photonics

Researchers Discovered a Way to Build Sophisticated Photonic Integrated Circuit That Interconnects Optical Data Superhighways

By revolutionizing the connectivity of current optical chips and swapping out bulky 3D-optics with a wafer-thin slice of silicon, a study headed by Monash and RMIT Universities and a University of Adelaide specialist has discovered a way to construct a sophisticated photonic integrated circuit that interconnects between data superhighways.

World first self-calibrated photonic-chip. Image Credit: Monash University / RMIT

This innovation, which was reported in the esteemed journal Nature Photonics, has the potential to accelerate the development of artificial intelligence on a worldwide scale and provides valuable real-world applications like:

  • Smaller switches for reconfiguring optical networks that carry the internet to get data where it is required faster.
  • Making natural language processing even quicker for apps such as Google Homes, Alexa, and Siri.
  • Permitting AI to more quickly analyze medical conditions
  • Safer driverless cars capable of promptly understanding their surroundings

The study of light, or photonics, is changing how humans live, whether it is by enabling TVs to be turned on or by maintaining satellites’ positions. The processing power of large bench-sized utilities can be transferred onto tiny photonic chips.

Dr Andy Boes developed the research as part of a joint Australian Research Council Discovery Project.

Dr Boes conducted this research while at RMIT and has apparently taken a place at the University of Adelaide, Professor Arthur Lowery from Monash University’s Department of Electrical and Computer Systems Engineering, and Dr. Mike Xu, who is now at Beijing University of Posts and Telecommunications.

Professor Arnan Mitchell and Dr Guanghui Ren planned the chip so it was ready for the experiment demonstration.

The project’s principal investigator, Monash University ARC Laureate Fellow Professor Arthur Lowery, asserts that this development builds on Dr Bill Corcoran’s earlier discovery of an optical microcomb chip that can transmit three times as much traffic as the entire NBN through a single optical fiber and is thought to be the fast broadband speed in the entire globe from a single fingernail-sized chip.

The optical microcomb chip constructed the superhighway’s various lanes, and the self-calibrating chip has now constructed the on and off ramps and bridges that link them together and facilitate faster data flow.

We have demonstrated a self-calibrating programmable photonic filter chip, featuring a signal processing core and an integrated reference path for self-calibration.

Arthur Lowery, Study Principal Investigator, ARC Laureate Fellow Professor, Monash University

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

Electronics saw similar improvements in the stability of radio filters using digital techniques, that led to many mobiles being able to share the same chunk of spectrum: our optical chips have similar architectures, but can operate on signals with Terahertz bandwidths,” he adds.

This invention has been three years in the making.

Dr Andy Boes is a Senior Lecturer at the School of Electrical and Electronic Engineering and the Institute for Photonics and Advanced Sensing (IPAS) at the University of Adelaide.

As we integrate more and more pieces of bench-sized equipment onto fingernail-sized chips, it becomes more and more difficult to get them all working together to achieve the speed and function they did when they were bigger.

Dr Andy Boes, Senior Lecturer, School of Electrical and Electronic Engineering, University Of Adelaide

We overcame this challenge by creating a chip that was clever enough to calibrate itself so all the components could act at the speed they needed to in unison,” added Dr Boes.

Upcoming internet-dependent technology will demand even quicker and more bandwidth, including self-driving cars, remote-controlled mines, and medical equipment.

To boost bandwidth, it is not only necessary to upgrade the optical fibers that carry our internet—it is also necessary to install small switches with a variety of colors and orientations so that data can be transferred simultaneously via numerous channels.

This research is a major breakthrough—our photonic technology is now sufficiently advanced so that truly complex systems can be integrated on a single chip.

Arnan Mitchell, Professor, InPAC

The idea that a device can have an on-chip reference system that allows all its components to work as one, is a technological breakthrough that will allow us to address bottleneck internet issues by rapidly reconfiguring the optical networks that carry our internet to get data where it’s needed the most,” he says.

In addition to being able to modify and direct optical information pathways, photonic circuits also include some computational capabilities, such as the capacity to look for patterns. Numerous applications, including search algorithms, driverless vehicles, internet security, threat detection, and medical diagnosis, depend on pattern searching.

New search jobs may be encoded into the chips with speed and accuracy, thanks to rapid and reliable reprogramming. Self-calibration fixes this issue. However, this manufacturing has to be accurate to the degree of a very small wavelength of light (nanometers), which is now challenging and very expensive.

Incorporating all the optical functionalities onto a device that could be “plugged in” to the current infrastructure was a significant difficulty for the research.

Our solution is to calibrate the chips after manufacturing, to tune them up in effect by using an on-chip reference, rather than by using external equipment,” says Professor Lowery, an ARC Laureate Fellow.

We use the beauty of causality, effect following cause, which dictates that the optical delays of the paths through the chip can be uniquely deduced from the intensity versus wavelength, which is far easier to measure than precise time delays. We have added a strong reference path to our chip and calibrated it. This gives us all the settings required to ‘dial up’ and desired switching function or spectral response,” he adds.

To make photonic chips practically viable, the approach is a crucial step. The scientists were able to adjust the chip in a single step, allowing for the speedy and reliable switching of data streams from one destination to another, as opposed to looking for a setting that is similar to tuning in an old radio.

The group has also been studying optical correlators, which can practically instantly discover patterns of data in data streams, like photographs, and which are made possible by the reliable tuning of photonic circuits.

Professor Nelson Tansu leads the School of Electrical and Electronic Engineering at the University of Adelaide.

The multi-university team’s work on this photonic integrated circuit demonstrates that this technology is becoming more readily available for pushing the system-level performance limits in the diverse areas that this technology is being used in,” he said.

Advances in photonic integrated circuitry rely on progress in semiconductor, quantum materials, device fabrications, and integration technology.”

These are critical research areas at the University of Adelaide and of great importance for creating sovereign capability in semiconductor manufacturing in Australia,” he added.

Journal Reference:

Xu, X., et al. (2022) Self-calibrating programmable photonic integrated circuits. Nature Photonics.

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