Description du sujet de thèse

Photonic integrated circuits (PICs) are microchips containing photonic components that interact to detect, generate, transport, and process light. A notable fabrication technique, direct laser writing (DLW) of PICs in glass, involves focusing an ultrashort laser inside the chip to modify its structural and chemical properties at the microscopic scale. DLW offers a unique advantage by enabling rapid prototyping of complex, high-precision structures based on 3D photonic waveguides. DLW is widely used to produce PICs with low-loss, high-fidelity optical components for classical and quantum information processing. Most DLW photonic systems are currently designed for visible and telecommunications and consist predominantly of passive components. There is now a critical need to develop integrated active photonic components operating in the mid-infrared (2-5 µm), particularly for medical and environmental applications, astronomical instrumentation, and quantum sensing, where compact, stable, and flexible PICs proposed by DLW [1] are of major importance. Among rare earth ions, Tm3+ has attracted considerable interest, mainly for the development of novel mid-infrared lasers [2]. Indeed, when excited at 800 nm, Tm3+ can emit at 1470 nm, which overlaps with the S-band of optical communication, and especially, between 1800 and 2200 nm. Glasses appear to be promising host materials for Tm3+ due to their relatively simple synthesis method and low production cost compared to those used for crystal preparation. Furthermore, the efficiency of emission processes is highly dependent on the glass systems and is very high in low-phonon energy glasses such as tellurite glasses.

In this context, the main objective of this thesis is to develop and fabricate a high-performance integrated light source emitting in the mid-infrared using DLW from novel Tm3+-doped tellurite glasses. Since a higher absorption/emission cross section and longer lifetime luminescence levels can be achieved if Tm3+ is present in crystals, glasses will be prepared from Tm3+-doped crystals using the glass-ceramic method, based on the nucleation and growth of nanoparticles. DLW technology will be used to fabricate integrated waveguiding microstructures directly embedded in these active glasses.

The main objectives of the thesis are:
- To synthesize Tm3+-doped tellurite glass materials and demonstrate enhanced MIR emission from crystals embedded in the glass;
- To improve the fundamental understanding of the photoresponse of tellurite glass materials to femtosecond IR laser radiation [3]
- To design, fabricate, and characterize active optical waveguides etched in crystals prepared with a metal nanoparticle precursor;
- To demonstrate the feasibility of active waveguides etched by femtosecond laser in crystals/metal particles containing tellurite glasses.

[1] A. Le Camus et al., Opt. Exp. 29, 8531 (2021).
[2] J. Wu et al., IEEE Photon. Technologie. Lett. 18, 334 (2006).
[3] G. Torun et al., Adv. Master's degree. 35, 2210446 (2023)

Practical Information
- Duration of the PhD: 48 months
- Industrial supervision: Fastlite by Amplitude
- Host laboratory: Institute of Physics of Nice (France)
- Thesis supervisor: Dr. Matthieu Bellec
- Co-host laboratory: University of Tampere
- Co-thesis supervisor: Prof. Laeticia Petit
- Secondments: Wlodzimierz Trzebiatowski Institute of Low Temperatures and Structures (Poland, 2 months) for the analysis of the spectroscopic properties of MIR glasses and glasses containing particles, Fastlite by Amplitude (France, 1 month) for the writing of waveguides with advanced laser pulse shaping, and Nazarbayev University (Kazakhstan, 1 month) for the characterization of active waveguides.

Contexte de travail

Over the past four decades, glass, glass-ceramics, and composites have contributed to the most advanced socioeconomic advances as high-tech materials. To compete with emerging economies such as China and India, the European glass industry must strive for leadership by investing more in research and innovation to develop new materials and train specialists for a competitive but promising market.

Contributing to this challenge is the primary objective of the "Structured Functional Glasses for Laser, Sensing, and Healthcare Applications" (FunctiGlass) project, dedicated to advanced high-tech materials for three sectors: light sources, sensors, and biological applications.

FunctiGlass, coordinated by the CNRS, is a unique interdisciplinary research and training program, offering a dual degree, within the framework of Horizon Europe's doctoral networks (Marie Sklodowska Curie Actions, project 101169415). It will train 11 doctoral students who will participate in a joint research training program based on very close cooperation between academia and industry. It will allow trainees to evolve in 11 academic environments (universities and research institutes) and 9 non-academic environments (industry and SMEs) representing 9 different countries. Each doctoral student will be supervised by two academic tutors from different countries (sharing their time between the two units) and one mentor (industrial partner) to ensure cross-sector knowledge sharing and the acquisition of transferable skills, focused on entrepreneurship and innovation. Thanks to the multidimensional training of the FunctiGlass program, the 11 doctoral students will excel in the economy of the future by acquiring a multidimensional perspective and mindset to become future leaders in glass science, and in particular in nano/microstructured glass-based materials. Through this program, they will find their own path to innovation, whether in academia or industry.

The project will create the necessary conditions for establishing lasting relationships between the academic and private sectors for the transfer of technology and skills. Five institutions will award the dual degrees: Université Côte d'Azur (Nice, France), Universities of Tampere (Finland), Gottfried Wilhelm Leibniz University Hannover (Germany), University of Milan-Bicocca (Italy), and the Research Institute for Low Temperatures and Structures of the Polish Academy of Sciences (Wroclaw, Poland).

Industrial partners: AOI Tech (France), Corning (France), Fastlite (France), Klearia (France), Else Nuclear (Italy), Nobula3D (Sweden), Nyfors Teknologi (Sweden), Rosendahl Nextrom (Finland), Scout Scientific Outsourcing (Poland).

Other project partner universities (not awarding doctorates): Cergy-Pontoise University (France), Ghent University (Belgium), Pardubice University (Czech Republic), Nazarbayev University (Kazakhstan), and Umeå University (Sweden).

For this four-year thesis, the host laboratory is the Nice Institute of Physics (Nice, France) and the thesis supervisor is Matthieu Bellec. The co-organizing laboratory is the Photonics Laboratory at the University of Tampere (Finland), with Laeticia Petit as co-supervisor. The candidate will divide their time between the two countries.

Project website: https://functiglass.eu

The position is located in a sector covered by the Protection of Scientific and Technical Potential (PPST), and therefore, in accordance with regulations, requires that your arrival be authorized by the competent MESR authority.
Constraints and Risks

The position is located in a sector covered by the Protection of Scientific and Technical Potential (PPST) and therefore requires, in accordance with regulations, that your arrival be authorized by the competent MESR authority.

Le poste se situe dans un secteur relevant de la protection du potentiel scientifique et technique (PPST), et nécessite donc, conformément à la réglementation, que votre arrivée soit autorisée par l'autorité compétente du MESR.

Contraintes et risques

The student will also receive a mobility allowance and a family allowance (depending on family circumstances) of up to €600 and €495 per month respectively. The doctoral student will share their time between the two universities, based on a long period in each country.