Integrated Photonics and Applications Centre (InPAC)

Welcome to the InPAC webpage. InPAC is a research centre within RMIT University (Melbourne, Australia), which focuses on applied research in photonic integrated circuits (PICs) and the translation of such PICs into industrial applications. For more information about the centre please click here.




Australian collaboration to deliver world-leading gyroscope technology

Australian researchers, and industry partners will collaborate to design and manufacture the world’s most precise, compact and cost-effective gyroscope, in a new $8.7 million project. Well done to Arnan Mitchell and Andy Boes on being a part of the industry-academia collaboration.

See the full RMIT story here.


Congratulations to Markus Knoerzer who just submitted his PhD thesis ‘Advanced interrogation methods for integrated photonic biosensors’ for examination. In this thesis he investigated optical biosensor systems. The research identified limitations in the methods for reading current interferometric optical biosensors and introduced new methods overcoming these limitations. The findings enable biosensors to be sensitive and precise but also stable and easy to use, advancing practical point-of-care diagnostics harnessing micro-chips.


InPAC last night published a new paper 'Ultra-dense optical data transmission over standard fibre with a single chip source' in Nature Communications, which provides a record capacity of 40 terabits-per-second from a single chip source through a single standard optical fibre, installed between the Monash and RMIT nodes of the centre.

Dr. Bill Corcoran provides a breakdown of this work in The Conversation, and you can explore the coverage of this work in wider news media

Want to get involved? Check out our open PhD positions


Great to see the work 'Ultra-efficient frequency comb generation in AlGaAs-on-insulator microresonators' of Dr. Lin Chang in collaboration with Dr. Andy Boes published in Nature Communications. In this contribution, we challenge this status quo and demonstrate a low loss AlGaAs-on-insulator platform with anomalous dispersion and quality (Q) factors beyond 1.5 million. Such a high quality factor, combined with high nonlinear coefficient and small mode volume, enabled us to demonstrate a Kerr frequency comb threshold of only ∼36 µW in a resonator with a 1 THz free spectral range, ∼100 times lower compared to that in previous semiconductor platforms.


Dr. Cesar S. Huertas was invited to talk about InPAC latest advances in the creation of Biomedical technology in the very inspiring session: “Innovation in Healthcare with Precision Medicine” at the RMIT Engaging For Impact 2020. Our innovative research in integrated photonics and microfluidics aims at improving diagnostic accuracy of complex diseases, such as diabetes, cardiac injuries and cancer, to foster the development of individually tailored therapies for more personalized medicine.


Andreas Frigg's work 'Optical frequency comb generation with low temperature reactive sputtered silicon nitride waveguides' has been in APL Photonics. In this work, we report on low-stress, high-confinement, dispersion-engineered SiN waveguides utilizing low temperature grown reactive sputtered thin-films. We demonstrate a microring resonator with an intrinsic quality factor of 6.6 × 10^5, which enabled us to generate a native free spectral range spaced frequency comb with an estimated on-chip pump power of 850 mW. Importantly, the peak processing temperature is 400°C making this approach fully back-end compatible for hybrid integration with preprocessed CMOS substrates and temperature sensitive photonic platforms such as lithium niobate on insulator.



Andreas Frigg published his research 'Low loss CMOS-compatible silicon nitride photonics utilizing reactive sputtered thin films' in Optics Express. It presents a back end of line (< 400°C), low loss SiN platform based on reactive sputtering for telecommunication applications. Waveguide losses of 0.6 dB/cm at 1580 nm have been achieved for moderate confined waveguides which appear to be limited by patterning rather than material. These findings show that reactive sputtered SiN thin-films can have lower optical losses compared to PECVD SiN thin-films, and thus show promise for future hybrid integration platforms for applications such as high Q resonators, optical filters and delay lines for optical signal processing.


Dr. Bill Corcoran presented his latest work 'Ultra-high data rate communications with a single soliton crystal micro-comb' at the Australian and New Zealand Conferences on Optics and Photonics (ANZCOP) at RMIT University. He demonstrated how optical frequency combs can be used to transmit record amount of data across a single optical fibre. The findings from this study will enable to increase the data capacity of currently employed fibres without the need of new fibre infrastructure.


Congratulations to Dr. Thach Nguyen who just published 'Microwave engineering filter synthesis technique for coupled ridge resonator filters' in Optics Express. In this paper he shows how recently reported ridge resonance structures can be arranged as coupled resonators with very close spacing and thus can be harnessed to achieved many of the filter functionalities available in the field of microwave engineering. The filter is comprised of multiple parallel ridges on a common silicon slab, with each resonator exhibiting a resonant frequency and quality factor which can be controlled through engineering the geometry of the ridge. He demonstrate through rigorous simulation how this approach can be used to achieve high order optical bandpass filters at 1.55 µm center wavelength with Butterworth or Chebychev responses and analyse the impact of non-ideal behaviours on filter performance.


Dr. Guanghui Ren just published his research 'Asymmetric transmission of light in hybrid waveguide-integrated plasmonic crystals on a silicon-on-insulator platform' in Optics Letters. It demonstrates asymmetric transmission of light in hybrid waveguide-integrated plasmonic crystals where triangular silver islands create a regular array of nanogaps, which couple to an underlying silicon-on-insulator optical waveguide. Up to 60% difference is observed between light transmission in the forward and backward directions. This asymmetric transmission of light is not caused by an external magnetic field or nonlinearity, but solely a consequence of the structure geometry.


Trends in personalized medicine has promoted the development of analytical tools for the detection of genetics and epigenetics biomarkers for more accurate and precise diagnosis. Dr. Cesar S. Huertas latest review: 'Advanced Evanescent-Wave Optical Biosensors for the Detection of Nucleic Acids: An Analytic Perspective' gives a comprehensive overview on the latest advances and challenges on the development of photonic biosensors for nucleic acid analyses. This work has been done in collaboration with the Nanobiosensors and Bioanalytical Applications Group (NanoB2A) from the Catalan Institute of Nanoscience and Nanotechnology (ICN2).


Congratulations to Thach Nguyen who just published his latest research titled 'Ridge Resonance in Silicon Photonics Harnessing Bound States in the Continuum' in Laser & Photonics Reviews. This work presents the theoretical analysis and experimental demonstration of a waveguide resonator based on bound states in the continuum. This phenomenon is experimentally demonstrated on a silicon photonic chip using foundry‐compatible parameters and it is interfaced on‐chip to standard single‐mode silicon nanowire waveguides. The fabricated chip exhibits a single sharp resonance near 1550 nm with a line width of a few nanometers, an extinction ratio of 25 dB, and a thermal stability of 19.5 pm/°C. It is believed that the demonstration of a resonance operating near a bound state in the continuum realized using guided wave components will form the basis of a new approach to on‐chip wavelength filtering and sensing applications.


Bill Corcoran's latest research 'Optical sampling to enhance Nyquist-shaped signal detection under limited receiver bandwidth' in Optics Express.

Insufficient receiver bandwidth destroys the orthogonality of Nyquist-shaped pulses, generating inter-symbol interference (ISI). We proposes using an optical pre-sampler to alleviate the requirement on the receiver bandwidth through pulse re-shaping. Experiments and simulations using an optically shaped 40-Gbaud Nyquist-shaped on-off-keying signal (N-OOK) show receiver sensitivity improvements of 4- and 7.1-dB under 18- and 11-GHz receiver electrical bandwidths, respectively.


Thach Nguyen's latest research 'Lateral Leakage in Silicon Photonics: Theory, Applications, and Future Directions' in IEEE Journal of Selected Topics in Quantum Electronics. This paper presents an overview of lateral leakage in silicon photonics due to polarization coupling between the guided mode of a ridge waveguide and unguided slab mode in the etched cladding. We explain the physical origins and provide insight into how this effect can be suppressed or harnessed. We show how lateral leakage can manifest as new resonant behaviour and explore this effect in the context of bound states in the continuum. We review a number of applications for devices based on lateral leakage and present outlook for a new generation of polarization manipulators, antennas and filters.


Andy Boes just published his work 'Improved second harmonic performance in periodically poled LNOI waveguides through engineering of lateral leakage' in Optics Express. This work investigated the impact of lateral leakage for linear and nonlinear optical waveguides in lithium niobate on an insulator and provides guidelines for designing waveguides in LNOI that do not suffer from the lateral leakage effect. By applying these design considerations, it was possible to avoid the lateral leakage effect at the second harmonic wavelength of a nonlinear optical waveguide in LNOI and demonstrate a peak second harmonic generation conversion efficiency of ~1160% W−1cm−2.


This year, the 11th eddition of the Advanced Study Course on Optical Chemical Sensors (ASCOS) has taken place at the University Center Bertinoro (Italy). Siew Joo Beh has attended to this proficient optical/chemical sensor course, where she learned alongside highly qualified selected tutors in a very relaxed atmosphere. The final test consisted of developing a biosensor for a given purpose applying all the insights gained during the course, where Siew's group won the first price! Congratulations!


Congratulations to Markus Knoerzer who just published his research 'Optical frequency comb based system for photonic refractive index sensor interrogation' in Optics Express, where he demonstrates how an optical frequency comb can be used to enhance the functionality of an integrated photonic biosensor platform. The proposed phase measurement approach is accurate, independent of the bias of the interferometer and robust against intensity fluctuations that are common to each of the comb lines.


Andreas Frigg and Islam Abdo presented this week their work at the Conference on Lasers and Electro-Optics (CLEO) Europe in Munich, Germany. Andreas Frigg presented his work titled 'Low stress, anomalous dispersive silicon nitride waveguides fabricated by reactive sputtering' and Islam Abdo presented 'Design Algorithm for Adiabatic Photonic Components using a Constant Coupling Approach '.


Andreas Frigg presented this week his work titled 'Low loss, plasma beam assisted reactive magnetron sputtered silicon nitride films for optical applications' at the Optical Interference Coatings conference in Santa Ana Pueblo, New Mexico, United States.


InPAC was awarded the Automotive Engineering Graduate Program (AEGP) grant that supports two PhD scholarships for the project "Advanced Integrated Photonics Circuits for Future Navigation Systems in Autonomous Driving Cars" with our Industry Partner Advanced Navigation. We are currently looking for PhD candidates to fill these positions, please find more information about the PhD positions here.


Congratulations to Dr Cesar S. Huertas who was awarded the RMIT Vice-Chancellor’s Postdoctoral Fellowship. This is a fantastic achievement and highlights his outstanding research in biophotonic devices.