Researchers Leverage Photonics in Radar System to Detect Down to the Millimeter

February 17, 2022 by Kristijan Nelkovski

Scientists from the University of Sydney have developed a new type of photonic radar system and sensor promising non-invasive medical monitoring.

As engineering advancements such as self-driving vehicles, home automation, and smart city designs become more prevalent in everyday life, engineers have a lot of work to do. Some tasks involve developing better and more efficient imaging technologies for high resolution and real-time sensing of a given environment.

Developing such technologies relies on innovating in new fields and reimagining current and old technologies.


A block diagram for a general radar system.

A block diagram for a general radar system. Image used courtesy of Aounallah and Khalfa


One such invention, called photonic radar, improves traditional radar technologies while having the potential to be integrated into existing systems and open the door for new and potentially life-saving applications.

This article will focus on some of the drawbacks of traditional radar for modern implementations and one new photonic radar technology currently being developed at the University of Sydney.


Traditional Radar Imaging Technologies

Radar or radio detection and ranging are some of the most widely used methods for the detection and tracking of objects, as well as analyzing their velocity and angular momentum. 

These systems have existed since the 1940s. In the beginning, their use was strictly connected with military operations during the second world war.

Since then, radar has found other uses in our everyday lives as a sensing tool for different types of devices and technologies. This adoption is because radar principles are generally quite simple and easy to operate and manufacture. 

Radar works by sending out short bursts of electromagnetic waves from a transceiver and calculating the time it takes for them to bounce back. Thus it can measure any object that comes in the way of the system and its distance and position relative to the measuring instrument.

Still, there are some drawbacks to traditional radar technologies' implementation in modern applications. Typically, radar systems are developed on a per case basis making individual systems proprietary depending on a small range of specific sensing needs.

Although some companies are working on standardizing radar development, individual applications often require vastly differing electronics, varying operational frequencies, and different power requirements, even if their development and software platforms are universal.

Despite the advancements of typical radar systems, there are still areas of improvement. One type of radar system aiming to provide a more accurate and precise radar uses photonics. 

A photonic radar promises a real-time imaging rate with higher image quality (resolution) to detect differences in millimeters instead of meters.


University of Sydney’s Photonic Radar Technology

One of the most recent advancements in photonic radar technology is a device developed at the University of Sydney dubbed 'advanced photonic radar.' 

Led by Professor Benjamin Eggleton and supported by the U.S. Air Force and the Australian Research Council, the team behind this project set out to improve radar and create an ultra-high-resolution imaging sensor.

Similar to regular radar, this system uses radio waves to measure the speed, location, and angular velocity of objects; however, some of its main components are manufactured using photonic circuits instead of electronic ones.

This use of photonics is what gives it an edge over traditional radar and an imaging resolution of millimeters instead of meters. 

Additionally, photonics reduces the hardware burden of a radar system while increasing its sampling precision and allowing for the use of a wider range of operational frequencies without any additional components.


Experimental setup schematic for the researcher's radar ranging demonstration. Image used courtesy of Liu et al


Decreasing the hardware burden, or in this case, essentially using fewer components to do more, would allow photonic radar systems to have universal uses, be energy and space-efficient, and do so at a lower cost when compared to traditional radar systems. 

This particular device is composed of: 

  • A photonic signal generator that generates ultra-wideband photonic signals
  • An optical to an electrical converter that translated these signals from photonic to microwave
  • RF antennas
  • A photonic signal mixing unit that demodulates the signal in the optical domain 
  • An electrical to optical converter for signal processing


Applications for Photonic Radar Systems

A photonic radar system has no limit to potential applications; however, professor Eggleton and Ph.D. candidate Ziqian Zhang are currently working on a future life-saving application for the medical monitoring field. 


 Ziqian Zhang (left) and Professor Benjamin Eggleton (right) showed over their radar system.

Ziqian Zhang (left) and Professor Benjamin Eggleton (right) showed over their radar system. Image used courtesy of the University of Sydney


Using their photonic radar sensor, the team wants to develop a novel way of detecting a patient's vital signs such as breathing and heart rate.

By continuously measuring subtle movements of a patient's body, this technology could detect their breathing pattern and determine potential irregularities without attaching any devices to the patient itself. This method would benefit non-invasive measurements of burn victims or infants that would otherwise be sensitive to traditional sensors and monitoring devices.

Similar measurements can be done by using video capturing technologies that carry more data and private information that users can use to identify patients. 

A photonic radar system can help with the privacy problem of medical monitoring as it would only be able to capture specific information related to a patient's health, allowing for complete privacy and anonymity while also complying with the laws and regulations in this area.


The Future of Photonic Radar Systems

This photonic radar system is still in development, and the researchers from the University of Sydney are planning multiple testing phases after receiving ethics approval. 

Their current plan is to test this technology on cane toads first and then move on to human participants. 

Thanks to the non-invasive nature of radio waves used in radar, vital sign medical devices based on this technology would be perfectly safe for widespread use in the home or hospital environments. 

In the future, the team is planning to shrink these sensors making them small enough to be embedded into mobile phones and other devices.