- Université Gustave Eiffel
- Research Field
- PhysicsPhysics » Condensed matter propertiesPhysics » Quantum mechanicsPhysics » Computational physics
- Researcher Profile
- First Stage Researcher (R1)
- Application Deadline
- Type of Contract
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- Hours Per Week
- Is the job funded through the EU Research Framework Programme?
- H2020 / Marie Skłodowska-Curie Actions COFUND
- Marie Curie Grant Agreement Number
- Is the Job related to staff position within a Research Infrastructure?
The mid-infrared (MIR) spectral region has numerous scientific interests and technological applications. In recent years, by the emergence of quantum cascade lasers (QCLs) as compact, reliable and commercially available semiconductor sources, even more applications have been empowered such as in telecommunication, defense, spectroscopy, etc. These sources can deliver up to hundreds of mW at room temperature. Passive mode-locking in QCLs remains one of the huge challenges because of the fast relaxation time of the excited carriers which is typically in the range of sub-picoseconds. The use of conventional techniques such as the semiconductor saturable absorber mirror is inefficient because the spatial hole burning effect dominates the carrier dynamics. To overcome this effect, longitudinal transition structures with relaxation time around 50 ps were proposed . However, mode-locking is assured with an external modulation at a cavity roundtrip frequency. We demonstrate a passive modelocking ability in MIR QCL by integrating a single-layer graphene used as a saturable absorber . The graphene has been integrated with a highly reflective mirror to increase the internal electric field and achieve the saturation intensity. We have shown that an optimized location corresponds to a distance of a quarter wavelength between the Bragg mirror and the graphene layer for which the electric field intensity attains the maximum value. Without graphene, the QCL operates in a continuous waves mode which means that the mode-locking failure. For a QCL structure with a vertical transition, SHB effect dominates because of the fast recovery time compared to the cavity roundtrip time. With T1=5 ps, multiple pulses per roundtrip are obtained in 2.6 mm cavity length. However, isolated pulses are obtained by reducing the cavity length to 1.8 mm. Thus, passive mode-locking of the MIR QCL is obtained by integrating a graphene reflective mirror but requires shorter cavity length for T1 in the range 0.5 – 1 ps. In this work, external cavity MIR QCL will be investigated for passive modelocking by integrating graphene. Recent work uses diffraction grating compensation which presents a complex configuration method to implement experimentally .
We have at Esycom Lab. an expertise on the modeling of semiconductor quantum devices, photonic integrated circuits and more recently quantum cascade lasers in MIR spectral region. We developed a simulation tools to determine the dynamic of the QCL through the resolution of Maxwell-Bloch equations for the gain section , . For the graphene layer, Maxwell-Ampere equation has been considered by the determination of a nonlinear conductivity from a saturable absorption coefficient. However, graphene layer can be modeling using Maxwell-Bloch equations which is efficient method for fast light interaction with matter but need to have the graphene physical parameters. Thus, in this PhD work such method will be used from experimental data of graphene. In addition, recent work in  proposes to describe graphene as a surface current with no optical thickness. This method was proved experimentally. For modelocking of QCL, saturable absorption effect could be included in such modeling.
The first mission consists in implementing Maxwell-Bloch equations or a new method to consider the single-layer graphene in FDTD.
The second aim is to participate to the characterization of frequency COMB QCLs or active modelocking QCL in LPENS (Laboratoire de Physique de l'école Normal Supérieur). This mission will permit to have an access to physical parameters of MIR QCLs to be used for the simulation setup.
The third mission deals with an experimental setup located at Nanyang Technological University (NTU / Cintra Singapore) where a commercial product of external cavity QCL is available. The objective will consist to insert graphene layer within the cavity to determine the effect on the laser dynamic.
The modeling activity will be carried out at the Laboratory of Electronics, Communication System and Microsystems (Esycom, UMR9007) and the experimental activity will be done in LPENS and NTU/Cintra Singapore.
• Maxwell-Bloch simulation using Finite-Difference Time-Domain (FDTD) method,
• Comparison of the two-level atom approximation and the multiple-level system,
• Study of MIR QCL with external cavity including graphene,
• Development of simulation tools to study the interaction of light-matter in external laser cavity using Maxwell-Bloch equations,
• Experimental characterization of QCLs, extraction physical parameters from measurement data of graphene layer.
• Writing of progress reports on the different results,
• Participation to international and national conferences and writing journal papers.
The thesis has a theoretical and an experimental aspects with an important part devoted to quantum/electromagnetic simulations towards device design and development. The work will involve electromagnetic simulations using a finite-difference time-domain method, testing of the realized devices using FTIR spectroscopy for example. The successful applicant will be an energetic individual with interest in semiconductor physics, quantum mechanics. She/he will have completed an undergraduate program in Physics, Optics or Electronic Engineering.
Ability to work in a team and to collaborate in a project context involving international collaborators.
Catherine Algani: firstname.lastname@example.org, Professor Esycom-Cnam
Elodie Richalot: email@example.com, Professor Esycom-UGE
Salim Faci: firstname.lastname@example.org, Associate Professor Esycom-Cnam
 A. Outafat et al. “Active Modelocking Improvement of MIR-QCL by Integrating Graphene as a Saturable Absorber”. In IEEE Journal of Quantum Electronics 58, 5 (2022), pp. 1–8. doi:10.1109/JQE.2022.3177220.
 A. Outafat et al. “Graphene Saturable Absorber Mirror for Passive Mode-locking of Mid-Infrared QCLs”. Accepted for publication in Optical and Quantum Electronics, doi: https://doi.org/10.21203/rs.3.rs-1991441/v1.
 A. Outafat et al. “Passive modelocking MIR quantum cascade laser incorporating self-induced transparency”. Optical and Quantum Electronics 54, 5 (May 2022), p. 283, doi:10.1007/s11082-022-03675-y.
 Philipp T ̃aschler et al. “Femtosecond pulses from a mid-infrared quantum cascade laser”. NaturePhotonics 15, 12 (Dec. 2021), pp. 919–924, doi:10.1038/s41566-021-00894-9, doi:https://doi.org/10.1038/s41566-021-00894-9.
 Christine Y. Wang et al. “Mode-locked pulses from mid-infrared Quantum Cascade Lasers”. In:Opt.Express17.15 (July 2009), pp. 12929–12943.doi:10.1364/OE.17.012929.
 Zhemi Xu et al. “Optical detection of the susceptibility tensor in two-dimensional crystals”. Communications Physics 4, 1 (Sept. 2021), p. 215, doi:10.1038/s42005-021-00711-3.
- Research Field
- Education Level
- Bachelor Degree or equivalent
- At the time of the deadline, applicants must be in possession or finalizing their Master’s degree or equivalent/postgraduate degree.
- At the time of recruitment, applicants must be in possession of their Master’s degree or equivalent/postgraduate degree which would formally entitle to embark on a doctorate.
- The thesis has a theoretical and an experimental aspects with an important part devoted to quantum/electromagnetic simulations towards device design and development. The work will involve electromagnetic simulations using a finite-difference time-domain method, testing of the realized devices using FTIR spectroscopy for example. The successful applicant will be an energetic individual with interest in semiconductor physics, quantum mechanics. She/he will have completed an undergraduate program in Physics, Optics or Electronic Engineering.
- Ability to work in a team and to collaborate in a project context involving international collaborators.
- High-quality doctoral training rewarded by a PhD degree, delivered by Université Gustave Eiffel
- Access to cutting-edge infrastructures for research & innovation
- Appointment for a period of 36 months based on a salary of 2 700 € (gross salary per month)
- Job contract under the French labour legislation in force, respecting health and safety, and social security: 35 hours per week contract, 25 days of annual leave per year
- International mobility will be mandatory
- An international environment supported by the adherence to the European Charter & Code
- Access to dedicated CLEAR-Doc trainings with a strong interdisciplinary focus, together with a Career development Plan
Applicants must fulfil the following eligibility criteria :
- At the time of the deadline, applicants must be in possession or finalizing their Master’s degree or equivalent/postgraduate degree
- At the time of recruitment, applicants must be in possession of their Master’s degree or equivalent/postgraduate degree which would formally entitle to embark on a doctorate
- At the time of the deadline, applicants must be in the first four years (full-time equivalent research experience) of their research career (career breaks excluded) and not yet been awarded a doctoral degree. Career breaks refer to periods of time where the candidate was not active in research, regardless of his/her employment status (sick leave, maternity leave etc). Short stays such as holidays and/or compulsory national service are not taken into account
- At the time of the deadline, applicants must fulfil the transnational mobility rule: incoming applicants must not have resided or carried out their main activity (work, studies, etc.) in France for more than 12 months in the 3 previous years
- One application per call per year is allowe
- Applicants must be available full-time to start the programme on schedule (November 1st 2023)
- Application rules are enforced by the French doctoral system which specifies a standard duration of 3 years for a full-time PhD together with the MSCA standards and the OTM-R European rules as follows
- Citizens of any nationality may apply to the programme
- There is no age limit
- Please refer to the Guide for Applicants available on the CLEAR-Doc website: https://clear-doc.univ-gustave-eiffel.fr/how-to-apply/useful-documents/
- The first step before applying is contacting the PhD supervisor. You will not be able to apply without an acceptation letter from the PhD supervisor.
- International mobility planned : The international mobility will take place at Cintra Singapore / NTU in the team of Qijie Wang. The PhD student will be located in Cintra's premises and will have access to all the facilities of Cintra.
- Please contact the PhD supervisor for any additional detail on job offer.
- There are no restrictions concerning the age, gender or nationality of the candidates. Applicants with career breaks or variations in the chronological sequence of their career, with mobility experience or with interdisciplinary background or private sector experience are welcome to apply.
- Support service is available during every step of the application process by email: email@example.com
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- Université Gustave Eiffel
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- 5, Boulevard Descartes
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