When science meets engineering

Interdisciplinary research team develops technology and prototype for a tunable and configurable radio frequency photonic filter


Researchers from the ARC Centre for Ultrahigh bandwidth Devices for Optical Systems (CUDOS) in the University of Sydney’s School of Physics and Australian Institute for Nanoscale Science and Technology (AINST) have achieved the final milestone in the development of a novel tunable and configurable photonic filter prototype.


Professor Benjamin Eggleton, Dr Eric Magi, Dr Amol Choudhary, Iman Aryanfar and Dr David Marpaung with the new tunable radio frequency (RF) photonic filter prototype

In a multi-year project, supported by the CUDOS ARC Centre of Excellence and the Asian Office of Aerospace Research and Development (AOARD), an interdisciplinary team of researchers working across three of the CUDOS projects Hybrid Integration, Terabit Communications and Stimulated Brillouin Scattering, developed a tunable radio frequency (RF) photonic filter prototype based on a nonlinear optical process, known as stimulated Brillouin scattering (SBS). In a significant milestone for the CUDOS program, the University of Sydney team have successfully delivered and demonstrated the RF Photonic filter prototype to key end users and stakeholders at the US Army Research Lab (ARL) in Adelphi, Maryland.

Radio frequency (RF) is a particular range of electromagnetic wave frequencies, used by most broadcast radio, television, wireless communications and radar signals. Interference mitigation is crucial in modern RF communications systems with dynamically changing operating frequencies, such as cognitive radios and modern military radar.

jamming signals

Frequency agile RF notch filters can remove interferers or jammers

“In an environment where there are lots of different signals, for example on a ship platform, these signals can sometimes interfere with other devices on the platform or mitigate jamming signals. The idea is to put a RF filter between the antenna and RF communications system to remove interferers or jammers with large variations in frequency, power and bandwidth,” CUDOS Laboratory Manager and senior researcher Dr Eric Magi said.

“Current RF filters are usually quite large and lack the tunability and precision. Our idea was to develop a new compact filter application specifically for radar signals. The filter needed to broadly tunable across tens of Gigahertz of frequency and provide high resolution and precise filtering.”


The self-contained prototype was designed and engineered within the School of Physics

This is where science meets engineering. Based on their research publications, in which the team demonstrates the technology - originally built on a 1.5m² optical table with electrical components provided by the School of Physics workshop team - they started to design a miniature, high performance frequency agile microwave filter technology prototype. The technology was patented in 2012 and a first prototype was finalised in 2013 to showcase the technology to potential stakeholders at various trade shows, including major international conferences such as CLEO:2014 Expo in San Jose, California.

In the framework of additional funding partner AOARD, the researchers conducted further key tests in their laboratories to improve the design and performance of the first prototype and develop a new tunable RF photonic filter prototype based on SBS.

“SBS is a coherent interaction of light and high frequency sound-waves that manifested in the generation of a high spectral resolution gain resonance. Combining SBS with a new concept of RF sidebands amplitude and phase control resulted in a notch filter with enhanced suppression through frequency selective interference,” senior researcher Dr David Marpaung said.

The filter has a unique capability of ultra-wide frequency tuning (20 GHz) combined with high spectral resolution (20 MHz) and very high rejection (>50 dB).

“Our technology provides a high-resolution filter function to cut off very small slices of interference over a large range – no other technology can do that. The novelty is that our prototype is totally tunable and can be reconfigured to a band-pass filter,” Dr Magi said.

Dr Eric Magi

Dr Eric Magi successfully demonstrated the operation of the prototype

The multi-year project reached now its final milestone: The unique capabilities of this new prototype were successfully showcased in March at the Army Research Labs (ARL), Adelphi MD, by senior researcher Dr Eric Magi who travelled to Adelphi with the prototype. Dr Magi demonstrated wideband tuning of the notch central frequency through the integrated control software as well as switching the filtering responses from high extinction notch filter to highly selective bandpass filter.

Following the successful demonstration of the new prototype, the research team is already looking at the next stage of this breakthrough project.

“The next stage involves the miniaturisation of the prototype using photonic integration based on silicon photonics, which offers the incorporation of SBS and components,” Dr Marpaung said.

“We demonstrated in a series of prototypes that all individual components can also be implemented on a chip, which is the end goal,” he added.

Professor Ben Eggleton, CUDOS Director and head of the Photonics group at the University of Sydney emphasised the importance of this milestone as part of CUDOS’ increased engagement with end users, particularly in the defence context.

“Our work in RF signal processing has attracted significant attention and interest from end users and defence industry in Australia and the USA. This reinforces our credibility and reputation as a word leading research group that can bridge breakthrough physics with advanced engineering and end user engagement.”


The end goal is to build the Tunable Microwave Photonic Filter Technology on a chip

Research collaborators

Additional information

The prototype is programmable and comes with a control software integration, developed by former CUDOS research assistant Shayan Shahnia, and a smart power controller for the optical modulator, developed by CUDOS PhD student Andri Mahendra, and available through his start-up nicslab. The technologies developed during the multi-year project are now licensed/patented.

The research was supported by U.S. Department of the Air Force AFOSR/AOARD (FA2386-16-1-4036); Australian Research Council (ARC) (CE110001018, DE150101535, FL120100029, DE170100585).


  1. A. Choudhary; B. Morrison; I. Aryanfar; S. Shahnia; M. Pagani; Y. Liu; K. Vu; S. Madden; D. Marpaung; B. J. Eggleton,
    "Advanced integrated microwave signal processing with giant on-chip Brillouin gain,"
    Journal of Lightwave Technology, vol.PP, no.99, pp.1-1doi: 10.1109/JLT.2016.2613558
  2. David Marpaung, Blair Morrison, Mattia Pagani, Ravi Pant, Duk-Yong Choi, Barry Luther-Davies, Steve J. Madden, and Benjamin J. Eggleton,
    "Low-power, chip-based stimulated Brillouin scattering microwave photonic filter with ultrahigh selectivity,"
    Optica 2, 76-83 (2015)
  3. Pant, R., Marpaung, D., Kabakova, I. V., Morrison, B., Poulton, C. G. and Eggleton, B. J. (2014),
    "On-chip stimulated Brillouin Scattering for microwave signal processing and generation,"
    Laser & Photon. Rev. doi: 10.1002/lpor.201300154
  4. Blair Morrison, David Marpaung, Ravi Pant, Enbang Li, Duk-Yong Choi, Steve Madden, Barry Luther-Davies, Benjamin J. Eggleton,
    "Tunable microwave photonic notch filter using on-chip stimulated Brillouin scattering,"
    Optics Communications, Volume 313, 15 February 2014, Pages 85-89, ISSN 0030-4018