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The Australian National University

Dr Stephen Madden

BSc(Eng) PhD DIC
A/Professor
ANU College of Science

Areas of expertise

  • Photonics, Optoelectronics And Optical Communications 020504
  • Photonics And Electro Optical Engineering (Excl. Communications) 090606
  • Classical And Physical Optics 020501
  • Polymers And Plastics 091209
  • Nanophotonics 100711
  • Nonlinear Optics And Spectroscopy 020503
  • Condensed Matter Characterisation Technique Development 020401
  • Ceramics 091201
  • Complex Physical Systems 029902
  • Optical Networks And Systems 100507
  • Surfaces And Structural Properties Of Condensed Matter 020406
  • Glass 091206
  • Nanotechnology 1007
  • Condensed Matter Physics 0204

Research interests

Fibre and Integrated optics, Planar waveguides, optical transmission systems, optical switching, MIR light generation and processing with integrated optics, Semiconductor processing methodology, Liquid crystals, optical polymers, Tellurite and Chalcogenide glasses and devices

Biography

Dr Madden currently leads research on Chalcogenide, Tellurite, and polysiloxane integrated optical devices at the Laser Physics Centre. His research career in fibre & integrated optics spans much of the period from 1984 to the present in start-ups, Multi-nationals, and academia covering a diverse range of areas including Liquid Crystals, seven different materials systems for planar devices, all fibre devices, Hybrid integration, Bragg gratings and devices, planar tunable lasers, optical transmission systems and all optical networking, and non-linear effects in SOAs and planar waveguide devices. The spectrum of work has covered fundamental science through to putting new high technology products into volume production and out onto the market.

Available student projects

General note for all potential applicants

Regrettably in the current funding environment we are unable to provide student stipends to overseas students, and so if you wish to apply from overseas we require that you obtain a suitable scholarship to support your living costs. The ANU has several schemes (see http://physics.anu.edu.au/education/graduate_scholarships.php for example) as do a number of countries (e.g. the Chinese Government CSC scholarship programme).

 

Mid-infrared Sensing

The current decade will see revolutions in sensing for healthcare, the environment, National Security, and industrial applications as Mid-Infrared (MIR) sensing systems come down in cost and expand in capability. The MIR region is technologically vital as pretty much all known chemical species have unique characteristic ro-vibrational absorption signatures in this region. A key innovation will be the advent of integrated on-chip sensing systems which will reduce the cost to the point that such systems become ubiquitously deployable. Currently there are two major barriers to this occurring; the lack of bright on-chip broadband MIR sources, and the absence of low cost array deployable MIR waveguide detectors. Several PhD projects are offered which could revolutionise the state of technology in these fields.

 

1). Mode Locked Lasers and Supercontinuum on a chip for sensing and instrumentation

We recently demonstrated an integrated planar waveguide nonlinear optical supercontinuum source generating broadband MIR light >100x brighter than a synchrotron [1]. Whilst offering ground breaking functionality, this source used an external mainframe laser for pumping, and these are bulky and expensive. To fully planar integrate such sources requires an on chip mode locked laser as a pump source. A fully integrated mode locked laser has never been demonstrated. To attain such a device requires a planar waveguide with high gain, passive waveguides which can be dispersion tailored and where pump couplers and mirrors can be built, and a waveguide saturable absorber. We have already demonstrated a high optical gain waveguide platform and suitable passive waveguides in Tellurium dioxide, and so are offering the opportunity to take this platform and make an on-chip mode locked laser. The project will require both theoretical and experimental work, the former to design the individual components comprising the laser as well as the total nonlinear cavity, and the latter involving the planar fabrication of the designed components and laser, and characterisation thereof. This project is being partly funded by Agilent through the support of the Stevens Creek Research Laboratories.

 

2). MIR waveguide detector arrays

Conventional wideband MIR detectors are based on narrow band gap semiconductors requiring exotic processing and are not easily integrated with conventional waveguide technology. In recent times it has become apparent that Graphene possesses photodetection capabilities, and very recently it has been found that this extends deep into the MIR in some circumstances. Additionally it has also been established that certain superconductor materials also enable MIR detection at the single photon level. Both of these technologies are well suited to integration onto chalcogenide glass waveguides (now established as an excellent MIR waveguide platform). This project seeks to examine the MIR photodetection in graphene and find the optimum waveguide & detector architecture for this as well as to characterise and optimise the MIR performance of waveguide superconducting nanowire detectors.  The project also includes collaboration with the UNSW and ANU LPC nodes of the Centre for Quantum Computing and Communication Technologies, and the world’s leading experts on Superconducting nanowire materials at NIST and Graphene detectors at TU Wein and Monash University.

 

3) MIR rare earth doped chalcogenide waveguide amplifiers

Analysis of MIR supercontinuum generation discussed above has clarified that to get the very broadband spectral coverage required for next generation sensing systems, a MIR pump at >3.5um is essential. Currently this requires the use of an optical parametric device, but interestingly chalcogenide glass hosts uniquely offer the properties required to enable rare earth lasing in glass hosts at wavelengths beyond 3.5um. However until recently there had been no demonstrations of rare earth doped amplifiers or lasers in such hosts beyond 1.3um. Very recently we achieved the first gain at 1.55um in a chalcogenide host using Erbium and also the first demonstration of a planar waveguide amplifier in a chalcogenide glass. Erbium also has a lasing transition at 3.5um and other rare earths offer longer lasing wavelengths. This project then aims to explore the materials and excitation challenges in making the world’s first chalcogenide MIR waveguide laser. The project will be heavily focussed on materials fabrication and excitation characterisation to determine the pump energy loss pathways with the goal of making a waveguide amplifier/laser using the simplest possible structure.

 

4) MIR waveguide sensor devices

The prime goal of MIR sensing devices is to enable ultrasensitive detection of chemical species for applications in health (breath diagnosis is a key target here), the environment, national security, agriculture and industry, and so this requires appropriate device architectures. Planar waveguide devices by their nature have a small cross section and confine most of their light in the waveguide and so the interesting question of how to increase sensitivity arises. This project seeks to investigate waveguide designs that maximise the overlap of the guided light with the material to be sensed and also resonant structures that increase sensitivity effectively by using multipass methods. Work will involve detailed optical modelling and optimisation of devices and architectures, fabrication and characterisation of planar waveguide integrated sensing structures, and ultimately demonstrations in real life settings such as breath analysis potentially in a healthcare setting.

 

5) Nonlinear integrated photonics

Whilst the work we have undertaken at the Laser Physics Centre over the last 10 years has laid an excellent foundation for highly integrated nonlinear optical devices on a chip, much remains to be done. Our current focus is on building nanophotonic devices to increase nonlinearity, loss compensation, non-linear processing in the presence of gain, and heterogenous integration of multiple optical waveguide platforms on a single chip. Work spans materials science to device architectures and full heterogeneously integrated device fabrication. We collaborate with a number of the world’s leading institutions in planar optics and nonlinear processing, (e.g. IMEC, Ghent, DTU, etc) and can offer a number of projects in the nonlinear planar devices arena.

 

6) Midinfrared Astrophotonics for Protoplanaet Exploration

The exact nature of the planetary formation process is still a scientific conundrum, and untangling this is difficult without direct observational evidence. However given that planets form in dust clouds and close to bright stars, observations are very difficult. The dust clouds can be penetrated and contrast maximised by going into the mid-infrared (MIR) region, and by using nulling interferometry, the central star can be cancelled from view leaving the protoplanet visible. However the interferometry requires an extremely stable self aligned platform that is only really feasible in an integrated optics implementation, and has never been demonstrated in the MIR. The Laser Physics Centre are world leaders in low loss MIR waveguide technology and this project would focus on the design, fabrication, and testing of suitable interferometric nullers in the 3-4.5um spectral region. This is a collaborative project with the University of Sydney and the Anglo-Australian Observatory, and is part of the CUDOS centre of excellence. Through these collaborations, access to the Subaru Telescope on Mauna Kea in Hawaii is possible to take the first actual MIR images if the project reaches a successful conclusion.

 

Publications

Projects and Grants

Grants information is drawn from ARIES. To add or update Projects or Grants information please contact your College Research Office.

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Updated:  18 January 2018 / Responsible Officer:  Director (Research Services Division) / Page Contact:  Researchers