Funding type: COFUND Marie Slodowska Curie Action
This project is under the Marie Skłodowska-Curie Actions (MSCA) program. There are no nationality conditions but the candidates must fulfill the MSCA mobility conditions, which means that she/he must not have stayed more than 1 year in France during the last 3 years immediately before the deadline of the call (31/05/2019)

Expected start date: 01/10/2019

Contacts:
Dr. Christian Grillet, CNRS/Ecole centrale de Lyon
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+ 33 4 72 18 62 53

Pr. Arnan Mitchell, RMIT
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websites:

• https://www.rmit.edu.au/about/our-locations-and-facilities/facilities/research-facilities/micronano-research-facility
• http://inl.cnrs.fr/en/ 

Collaborations/External partners : 3D oxides

Domain and scientific context :

The Mid-infrared  (Mid-IR) wavelength range - from 2.5 to 13 µm - is currently experiencing a huge surge in interest for an enormous range of applications that affect almost every aspect of our society, from compact and highly sensitive biological and chemical sensors, imaging, defense and astronomy. A notable feature of the Mid-IR is that most chemical and biological compounds that relate to our health, safety and environment have a strong spectral signature in this spectral range. The Mid-IR therefore offers unique opportunities for the development of technologies with a high societal (sensor applications, defence, industrial and environmental security, etc.) and fundamental impact (chemistry, biology, astrophysics, etc.).
Many actors in the nanophotonics scene have invested in this theme in the USA (Air Force research lab, Harvard, UCLA, Princeton MIRTHE, IBM, Cornell etc...), Australasia and Europe (INL, C2N, University of Surrey, Southampton, University of St Andrews, Ghent/IMEC).

Keywords : Lasers, nanophotonics, nonlinear optics, integrated optics, heterogeneous integration

Objectives and scientific challenges:

Despite its recognized potential, Mid-IR technologies are still limited in their range of applications, largely because of the size of the Mid-IR devices (optical components operating in this wavelength range have long been restricted to discrete components operating in free space, and to simple passive guides, generally based on multimode chalcogenide fibres) and the prohibitive costs of the instruments used due to the lack of compact Mid-IR optical devices.
Our strategy is therefore based on the development of an integrated hybrid Mid-IR platform , involving the miniaturization of optical components and their integration on a planar substrate made of materials with remarkable optical properties (particularly in terms of transparency and non-linearities) at MIR wavelengths like SiGe alloys , ,  and LiNbO3 . Heterogeneous integration with material platform transparent in the visible and near-infrared (like SiTiO2  and innovative oxides developed by our collaborator - 3D oxides), will also be pursued in order to access the full spectral range from visible to mid-IR.
The student's project will focus on one of the fundamental issues of integrated Mid-IR, namely efficient and broadband MIR sources and their integration into an optical circuit.

In this thesis, we will pursue an original approach using multimode and hybrid waveguides (based on thin-ridge concept  initially developed at RMIT) in order to exploit nonlinear-phenomena over an unprecented wavelength range (from visible to Mid-IR). The aim here will be to develop an on-chip supercontinuum (and potentially combs) broadband from visible to mid-IR

Expected original contributions :

• First supercontinuum on an integrated hybrid platform extending from visible to mid-IR above 8 µm and potentially up to 13 µm
• First supercontinuum exploiting integrated multi mode waveguides
• First demonstration of a frequency comb or frequency mixing on a multimode waveguide-based resonator.  

Research program and methodology :

The student will be involved at all stages of the project from the design of the devices using commercial or in-house developed electromagnetic modelling tools such as FEMSIM, FDTD, Schroedinger non-linear equations, the manufacture of the devices by clean room processes via the NANOLYON nanotechnology platform and the Micro Nano Research Facility - MNRF at RMIT (nanolithography, etching) and their optical characterizations.  
The student will be working with the Nanophotonics, Mid-IR team at the INL ECL site led by Dr. Grillet and the InPAC centre led by Prof. Arnan Mitchell in RMIT. The student will benefit from INL's and RMIT’s resources and expertise in integrated photonics and non-linear optics (C. Monat, ERC grant holder, Thach Nguyen) and new oxide platforms (S. Cueff, Andy Boes), both in terms of device design (the student will rely on INL and RMIT's theoretical and numerical expertise as well as the electromagnetic simulation tools available at both laboratories) and on technology and clean room manufacturing aspects for the production of the first basic demonstrators.

The student will work closely with our industrial partner 3D oxides on the oxide platforms in particular to optimise these new material platform (SiTiO2, transition metal oxides ect…) in the context of integrated photonics (losses, high nonlinearity ect…), and the deposition process.
The student will spend most of the time in the 1st and 3rd year at INL ECL and the 2nd year at RMIT in the InPAC centre, as indicated below.

Year1: Mostly at INL.

• Literature review of materials and material combinations that offer unique Mid-IR optical properties and nonlinear waveguide design capabilities
• Design of the nonlinear optical waveguide for supercontinum generation using commercial and in-house developed electromagnetic modelling tools.
• Establishing the fabrication capability for novel heterogeneous integrated photonic devices in the NANOLYON.

Year 2: Mainly at RMIT.

• Design and simulate and prototype multimode waveguides for supercontiuum generation.
• Investigate novel dispersion engineering methods on a multimode-waveguide resonator
• Experimentally characterise the linear and nonlinear properties of prototype multi-mode waveguides in the near and mid-IR (with collaborators at ANU).

Year 3: Mainly at INL.

• Realisation, characterisation of optimised devices (including harnessing 3D oxides approach of lateral and longitudinal varying material properties).
• Writing of the thesis

Scientific supervision:

• Description of the supervision committee :

• Integration inside the laboratories (percentage of working time inside these laboratories) : 67% at INL, 33% at RMIT

PhD funding : Co-Fund Marie Sladowska Curie Action (MSCA) ECL/RMIT (ECLAUsion program)

Profile of the candidate :

The required skills for the intern will be a good knowledge and a solid background in the field of solid-state physics, optics, nonlinear optics, and semiconductor devices. S/he should work towards his/her Masters/honours or Engineering degree in a field appropriate to one of these areas. An experience in photonics, clean-room fabrication, material deposition or optical modeling and characterization will be strongly appreciated.

Objectives for the valorization of the research work :

The results obtained will be published in peer-reviewed journals with a high impact factor and presented at international conferences in the field (CLEO-US/Europe, SPIE photonics Europe, NLO...). No patent filing or confidentiality constraints are envisaged, but this could change (in consultation with our collaborators).

Skills that will be developed during the PhD :

The student will develop the complete range of "nanophotonics / nanotechnology" skills, from device design (simulation and design of optical microcomponents using different modelling techniques including FDTD-Finite difference time domain, BPM-Beam propagation method, FEM-finite element method, Nonlinear Schrodinger equation) and their integration into a circuit using an industry standard design framework, the manufacture of these components in clean room environments (from deposition, growth to electron beam lithography, chemical etching and dry etching), their characterization (within a complete optical bench - wafer coupling, microreflectivity, Fourier optics, non-linear characterization, pulsed laser, parametric processes - that the student will have contributed to design and deploy) and data processing.

The highly collaborative and international environment of the project will require the student to develop, in addition to technical and scientific skills, communication, teamwork and project management skills.

Professional opportunities after the PhD:

This conceptual, scientific and technological work on the creation of a new generation of photonic components operating from visible to mid-IR will result in the emergence of a platform that is completely different from current technologies. This platform will therefore be a milestone for new scientific and technological advances in the many fields of science and industry that can benefit from the mid-infrared. The future prospects for the student, at the end of his/her thesis, are therefore extremely rich, with the possibility of pursuing an academic career in a prestigious photonics laboratory or entering an industrial field that will be eager for the skills developed by the student.

Bibliographic references about the PhD topic :

1. F. K. Tittel, D. Richter, and A. Fried, “Mid-Infrared Laser Applications in Spectroscopy,” in Solid-State Mid-Infrared Laser Sources, (Springer Berlin Heidelberg, 2003).
2. R. Soref, “Mid-infrared photonics in Silicon and Germanium,”Nat. Photonics 4, 495 (2010)
3. L. Carletti, P. Ma, Y. Yu, B. Luther-Davies, D. Hudson, C. Monat, R. Orobtchouk, S. Madden, D. J. Moss, M. Brun, S. Ortiz, P. Labeye, S. Nicoletti, and C. Grillet, "Nonlinear optical response of low loss silicon germanium waveguides in the mid-infrared," Opt. Express 23, 8261-8271 (2015)
4. L. Carletti, M. Sinobad, P. Ma, Y. Yu, D. Allioux, R. Orobtchouk, M. Brun, S. Ortiz, P. Labeye, J. M. Hartmann, S. Nicoletti, S. Madden, B. Luther-Davies, D. J. Moss, C. Monat, and C. Grillet, "Mid-infrared nonlinear optical response of Si-Ge waveguides with ultra-short optical pulses," Opt. Express 23, 32202-32214 (2015)
5. M. Sinobad, C. Monat, B. Luther-Davies, P. Ma, S. Madden, D. J. Moss, A. Mitchell, D. Allioux, R. Orobtchouk, S. Boutami, J.M. Hartmann, J-M. Fedeli, and C. Grillet, "Mid-infrared octave spanning supercontinuum generation to 8.5  μm in silicon-germanium waveguides," Optica 5, 360-366 (2018)
6. A. Boes, B. Corcoran, L. Chang, J. Bowers, A. Mitchell, “Status and Potential of Lithium Niobate on Insulator (LNOI) for Photonic Integrated Circuits, "  Laser & Photonics Reviews 2018, 12, 1700256. https://doi.org/10.1002/lpor.201700256
7. T. Kornher, K. Xia, R. Kolesov, B. Villa, S. Lasse, C. S. Sandu, E. Wagner, S. Harada, G. Benvenuti, H-W. Becker, and J. Wrachtrup, “Amorphous Silicon-Doped Titania Films for on-Chip Photonics,” ACS Photonics 2017 4 (5), 1101-1107
   DOI: 10.1021/acsphotonics.6b00919
8. M. A. Webster, R. M. Pafchek, A. Mitchell and T. L. Koch, "Width Dependence of Inherent TM-Mode Lateral Leakage Loss in Silicon-On-Insulator Ridge Waveguides," in IEEE Photonics Technology Letters, vol. 19, no. 6, pp. 429-431, March15, 2007.
   doi: 10.1109/LPT.2007.891979