Stefan DILHAIRE is member of Photonique & Matériaux team, his research field is Ultra Fast & Nano Scale Energy Transfer

Stefan Dilhaire’s group studies mutual interaction of heat, light and electricity in microsystems and nanomaterials and its applications in renewable energy (thermoelectricity, thermionicity, Organic photo generation), in microelectronics, in nanoplasmonics, in biology (ultrasonic imaging of cells).

The group is currently involved in 3 actions:

  • Nanoscale ultrafast energy transport (Nano thermal physics, Picosecond ultrasonics, Thermal properties identification),
  • Imaging (Integrated circuits temperature mapping),
  • Technology Transfer (Development of new optical techniques such as Heterodyne optical sampling aka ASOPS)

The research field concerns the study of mechanisms of transport of energy in nano-materials. These mechanisms can be achieved by phonons, plasmons, phonons polaritons. Materials consist in nano-particles, of nanowires, super-lattices or nanometric layers. The challenges are of:

  • working and characterising energy transport of matter at the nanoscale
  • uncorrelate the electric properties from the thermal properties.

Applications have repercussions in the fields of renewable energies (thermoelectricity), microelectronics as well as biology (laser ultrasound imaging of live cells)

Innovative imaging

Two Experimental Approaches

  1. Scanning thermal microscopy (SThM) : This method is an AFM based technique where the tip is instrumented with a temperature sensitive apex able to heat and probe at the same time. Scanning the tip produces images contrasted by the thermal conductivity of the sample with a nanometric lateral resolution. SThM was successfully applied to the characterization of thermal transport in nanowires.
  1. Femtosecond pump-probe Imaging :Femtosecond transient thermoreflectance is used for measuring temperature changes at a surface with high temporal resolution (100fs). It employs as a probe the thermally induced change in the optical constants of the metal by measuring the intensity of a light beam being reflected at the surface under consideration. However, since the optical constants are not very sensitive to the temperature, signals obtained are usually small, and enhancement of the sensitivity of the method is desirable. For that, we use an ultra fast heterodyne pump-probe spectroscopy.  This patented dual laser method achieves pump-probe delay times without a linear translation stage, but by using the beat frequency of two slightly detuned cavity-length-locked lasers instead.  The lack of a physical delay stage removes artifacts relating to alignment and beam walking.  The total pump-probe delay time, equal to the repetition period of the pump laser (~10s of ns) is collected in the beat period between the two lasers, ~10s of ms, and is ideal for high resolution microscopy.

Research Fields

Research Fields

  1. Ultrafast Energy Transfer at the nanoscale: Nanoplasmonics

Light propagating in concert with electrons along a metal surface may one day be used to turn microchips into optical processors. We showed that the loss of energy suffered by such metal-skimming light waves can be reduced if the waves are produced at a nanoscale slit in the metal film that carries the waves. The measurements are the first to provide a direct probe of the light losses in the vicinity of a subwavelength aperture. This effect is the result of interference between two different kinds of waves generated by the slit.

Weused a 300-nanometer-wide slit in a gold film deposited on a glass substrate. The film was illuminated from below with an infrared (800 nanometer) laser pulse, producingSPPs on the top surface, propagating outward, perpendicular to the slit direction. As the waves died out and were absorbed by the metal, they heated it enough to affect the surface’sability to reflect light. The SPP absorption wasprobed by firing a second, time-delayed laser (532 nanometers) at many locations on the top of the film and detected the reflected light. These so-called thermoreflectance data showed a plateau between 5 and 15 micrometers from the slit, which meant that the absorption was constant over this region.

  1. Ultrafast Energy Transfer at the nanoscale: Nanophononics

The ability to precisely control the thermal conductivity (k) of a material is fundamental in the development of on-chip heat management or energy conversion applications. Nanostructuring permits a marked reduction of k of single-crystalline materials, as recently demonstrated for silicon nanowires. However, silicon-based nanostructured materials with extremely low k are not limited to nanowires. By engineering a set of individual phonon-scattering nanodot barriers we have accurately tailored the thermal conductivity of a single-crystalline SiGe material in spatially defined regions as short as ∼15 nm. Single-barrier thermal resistances between 2 and 4×10−9 m2 K W−1 were attained, resulting in a room-temperature k down to about 0.9 W m−1 K−1, in multilayered structures with as little as five barriers. Such low thermal conductivity is compatible with a totally diffuse mismatch model for the barriers, and it is well below the amorphous limit. The results are in agreement with atomistic Green’s function simulations.… tobecontinuedin…Precise control of thermal conductivityat the nanoscalethroughindividual phonon-scatteringbarriers (Nature Materials 9, 491–495 (2010))

  1. Advanced Imaging: Filming a temperature field at 10 Tera Images per second

The problem for the experimenter is how to measure electron temperature, Te, resulting from optical absorption. Non-contact techniques like optical reflection are ideal but require knowledge about the variation of reflectivity with Te. In noble metals, the reflectivity can be successfully utilized for this purpose.The relative change in reflectivity has a large magnitude and ∆R/Rscales almost linearly with electron temperature. A linear relationship between ∆R/R and Teopens the way for a simple analysis of measured transient reflectivities.LOMA is specialized in thermal imaging and ultra-fast heat transfer analysis. Our expertise in the area of Heterodyne Time Domain Thermoreflectance (HTDTR) is at the state of the art.We have demonstrated that pump-probe experiments are of great use to measure thermal properties on thin films and nano-structured materials. The use of ultra-short laser pulses (100 fs) in pump-probe experiments allows characterizing thermal properties of nano-objetcs. LOMA has developed an unique expertise in heterodyned femto-second sources rendering temporal sampling purely optical thus dividing the acquisition time by 3 orders of magnitude.

  1. Advanced imaging: Thermal transport in individual nanowires

Thermal imaging of individual silicon nanowires (Si NWs) is carried out by a scanning thermal microscopy (SThM) technique. The vertically aligned Si NWs are fabricated combining nanosphere lithography and metal-induced wet chemical etching. A thermal model for the SThM probe is implementedfor the probe calibration, and to extract thermal parameters from the sample under study. Using this model combined with the experimental thermal images, we determine a mean value of the tip-to-sample thermal contact resistance and a mean value of the Si NWs thermal conductivity. SThM is actually the only technique available to perform thermal measurements simultaneously on an assembly of individual one-dimensional nanostructures. It enables a statistical process of thermal data in order to deduce a reliable mean thermal conductivity.

  1. Industrial applications 

Pump-probe experiments are of great use to measure thermal properties on thin films and nano-structured materials. The use of ultra-short laser pulses (100 fs) in pump-probe experiments allows characterizing thermal properties of thin films. However, access to long pump-probe delay times (10’s of nanoseconds) in a reliable way with a reasonable time measurement (few minutes) remains impossible in classical pump-probe experiments, as they are limited by physical modulation of laser path length. LOMA has developed an unique expertise in heterodyned femto-second sources rendering temporal sampling purely optical thus dividing the acquisition time by 3 orders of magnitude. Thermal conductivity screening on a substrate containing an array of samples with different thermal conductivities is now accessible in routine. Filming the thermal response to a light flash of a whole surface allows to map the thermal properties at once, thereby considerably reducing the acquisition time.

The group has developed a unique expertise at the state of the art in heterodyned femto-second sources rendering temporal sampling purely optical thus lowering the acquisition time by 3 orders of magnitude in comparison to classical techniques. We are currently doing researche and development with different laser companies.




A. Shakouri (UC Santa Cruz, University of Purdue USA), T. Baba (Tsukuba Japan), J. Altet (UPC, Spain), S. Volz (ECP Paris), N. Mingo (CEA Grenoble), G. Tessier (ESPCI Paris), B. Audoin (I2M Bdx), J.C Batsale (I2M Bdx), S. Ravaine (CRPP Bdx), G. Hadzianou (LCPO, Bdx), Philippe Lalanne, (IOGS-LP2N Bdx), Pierre-Michel Adam UTT (Troyes), Guillaume Duchateau, (CELIA-CEA Bdx).


My publications in Hal Archive


  1. A. Ben Amor, D. Djomani, M. Fakhfakh, S. Dilhaire, L. Vincent and S. Grauby, Si and Ge allotrope heterostructured nanowires: experimental evaluation of the thermal conductivity reduction, Nanotechnology, Volume 30, Number 37, (2019).
  2. Lalanne, P., Coudert, S., Duchateau, G., Dilhaire, S., Vynck, K. Structural Slow Waves: Parallels between Photonic Crystals and Plasmonic Waveguides, ACS Photonics, 6 (1), (2019)
  3. Petsagkourakis, I., Pavlopoulou, E., Cloutet, E., Chen, Y.F., Liu, X., Fahlman, M., Berggren, M., Crispin, X., Dilhaire, S., Fleury, G., Hadziioannou, G, Correlating the Seebeck coefficient of thermoelectric polymer thin films to their charge transport mechanism, Organic Electronics: physics, materials, applications, 52, pp. 335-341, (2018).
  4. Lozan, O., Sundararaman, R., Ea-Kim, B., Rampnoux, J.-M., Narang, P., Dilhaire, S., Lalanne, P., Increased rise time of electron temperature during adiabatic plasmon focusing, Nature Communications, 8 (1), art. no. 1656, . (2017)
  5. Coffy, E., Dodane, G., Euphrasie, S., Mosset, A., Vairac, P., Martin, N., Baida, H., Rampnoux, J.M., Dilhaire, S., Anisotropic propagation imaging of elastic waves in oriented columnar thin films,  Journal of Physics D: Applied Physics, 50 (48), art. no. 484005, . (2017)
  6. D’Acremont, Q., Pernot, G., Rampnoux, J.-M., Furlan, A., Lacroix, D., Ludwig, A., Dilhaire, S., High-throughput heterodyne thermoreflectance: Application to thermal conductivity measurements of a Fe-Si-Ge thin film alloy library, Review of Scientific Instruments, 88 (7), art. no. 074902, (2017)
  7. Furlan, A., Grochla, D., D’Acremont, Q., Pernot, G., Dilhaire, S., Ludwig, A., Influence of Substrate Temperature and Film Thickness on Thermal, Electrical, and Structural Properties of HPPMS and DC Magnetron Sputtered Ge Thin Films, Advanced Engineering Materials, 19 (5), art. no. 1600854, .(2017)
  8. Petsagkourakis, I., Pavlopoulou, E., Portale, G., Kuropatwa, B.A., Dilhaire, S., Fleury, G., Hadziioannou, G., Structurally-driven enhancement of thermoelectric properties within poly(3,4-ethylenedioxythiophene) thin films, Scientific Reports, 6, art. no. 30501, (2016)
  9. Michaud, J., Béchou, L., Veyrié, D., Laruelle, F., Dilhaire, S., Grauby, S., Thermal Behavior of High Power GaAs-Based Laser Diodes in Vacuum Environment, IEEE Photonics Technology Letters, 28 (6), art. no. 7347350, pp. 665-668. (2016)
  10. Casanova, A., D’Acremont, Q., Santarelli, G., Dilhaire, S., Courjaud, A., Ultrafast amplifier additive timing jitter characterization and contro, lOptics Letters, 41 (5), pp. 898-900. (2016)
  11. Chandezon, J., Rampnoux, J.-M., Dilhaire, S., Audoin, B., Guillet, Y. In-line femtosecond common-path interferometer in reflection mode (2015) Optics Express, 23 (21), pp. 27011-27019
  12. Savelli, G., Silveira Stein, S., Bernard-Granger, G., Faucherand, P., Montés, L., Dilhaire, S., Pernot, G. Titanium-based silicide quantum dot superlattices for thermoelectrics applications (2015) Nanotechnology, 26 (27), art. no. 275605
  13. Dehoux, T., Ghanem, M.A., Zouani, O.F., Rampnoux, J.-M., Guillet, Y., Dilhaire, S., Durrieu, M.-C., Audoin, B. All-optical broadband ultrasonography of single cells (2015) Scientific Reports, 5, art. no. 8650
  14. Rojo, M.M., Martín, J., Grauby, S., Borca-Tasciuc, T., Dilhaire, S., Martin-Gonzalez, M. Decrease in thermal conductivity in polymeric P3HT nanowires by size-reduction induced by crystal orientation: New approaches towards thermal transport engineering of organic materials (2014) Nanoscale, 6 (14), pp. 7858-7865 .
  15. O. Lozan, M. Perrin, B. Ea-Kim, J. M. Rampnoux, S. Dilhaire, and P. Lalanne, Anomalous Light Absorption around Subwavelength Apertures in Metal Films, Phys. Rev. Lett. 112, 193903 (2014)
  16. A. Abbas, Y. Guillet, J.-M. Rampnoux, P. Rigail, E. Mottay, B. Audoin, and S. Dilhaire, Picosecond time resolved opto-acoustic imaging with 48 MHz frequency resolution, Optics Express, Vol. 22, Issue 7, pp. 7831-7843 (2014)
  17. M. Muñoz Rojo, S. Grauby, J.-M. Rampnoux, O. Caballero-Calero, M. Martin-Gonzalez and S. Dilhaire, Fabrication of Bi2Te3 nanowire arrays and thermal conductivity measurement by 3ω-scanning thermal microscopy, J. Appl. Phys. 113, 054308 (2013)
  18. Karim Aissou, Jonah Shaver, Guillaume Fleury, Gilles Pécastaings, Cyril Brochon, Christophe Navarro, Stéphane Grauby, Jean-Michel Rampnoux, Stefan Dilhaire and Georges Hadziioannou, Nanoscale Block Copolymer Ordering Induced by Visible Interferometric Micropatterning: A Route towards Large Scale Block Copolymer 2D Crystals, Adv. Mater. 25, 213–217 (2013)
  19. S. Dilhaire, G. Pernot, G. Calbris, J. M. Rampnoux, and S. Grauby, Heterodyne picosecond thermoreflectance applied to nanoscale thermal metrology, J. Appl. Phys. 110, 114314 (2011)
  20. Altet, J., Mateo, D., Perpiñà, X., Grauby, S., Dilhaire, S., Jordà, X., Nonlinearity characterization of temperature sensing systems for integrated circuit testing by intermodulation products monitoring, Review of Scientific Instruments 82 (9) , art. no. 094902, 2011
  21. Pradere, C., Clerjaud, L., Batsale, J.C., Dilhaire, S., High speed heterodyne infrared thermography applied to thermal diffusivity identification, Review of Scientific Instruments 82 (5) , art. no. 054901, 2011
  22. Etienne Puyoo, Stéphane Grauby, Jean-Michel Rampnoux, Emmanuelle Rouvière, and Stefan Dilhaire,  Scanning thermal microscopy of individual silicon nanowires, J. Appl. Phys. 109, 024302 (2011)  
  23. Thermal exchange radius measurement: Application to nanowire thermal imaging, Puyoo, E., Grauby, S., Rampnoux, J.-M., Rouviere, E., Dilhaire, S. , Review of Scientific Instruments 81 (7), art. no. 073701  (2010)
  24. Aldrete-Vidrio, E., Mateo, D., Altet, J., Salhi, M. A., Grauby, S., Dilhaire, S . Strategies for built-in characterization testing and performance monitoring of analog RF circuits with temperature measurements. Measurement Science and Technology, 21(7)  (2010)
  25. Heterodyne method with an infrared camera for the thermal diffusivity estimation with periodic local heating in a large range of frequencies (25 Hz to upper than 1 kHz), Lilian Clerjaud, Christophe Pradere, Jean-Christophe Batsale and Stefan Dilhaire, Quantitative InfraRed Thermography Journal Volume 7, Issue 1, 2010
  26. G. Pernot, M. Stoffel, I. Savic, A. Jacquot, J. Schumann, G. Savelli, A. Rastelli, O.G. Schmidt, J. M. Rampnoux, S. Dilhaire, M. Plissonnier, S. Wang, and N. Mingo, “Precise control of thermal conductivity at the nanoscale via individual phonon barriers”, Nature Materials, Volume : 9, Pages : 491–495 (2010)

Book Chapters

  1. Handbook of Semiconductor Nanostructures and Nanodevices, Edited by A. A. Balandin and K. L. Wang, USA, ISBN: 1-58883-073-X, Chapter 29 « Scanning Thermal MicroscopyApplied to Thin films and ElectronicDevicesCharacterization », S. Volz, S. Dilhaire, S. Lefebvre, L.D.Patino-Lopez.
  2. Micro et Nano thermique manuscrit, éditions du CNRS, ISBN 978-2-271-06462-2 Chapitre 10 : Méthodes optiques, Stefan Dilhaire, Danièle Fournier, Gilles Tessier
  3. Microscale and nanoscaleheattransfer / SebastianVolz (ed.) ; in collaboration with Rémi Carminati, Patrice Chantrenne, Stefan Dilhaire, Séverine Gomez, Nathalie Trannoy, Gilles Tessier., Ed Springer, ISBN : 978-3-540-3605-6


– Surface preparation method
Publication number: 20150140267
Abstract: The invention relates to a process for the preparation, by spatial distribution of light intensity, of a surface in relief promoting order and spatial coherence serving as a guide for the organization, on nano- and micrometre scales, of an overlayer on the surface in particular of block copolymers.

– Optical Heterodyne Sampling Device
Publication number: 20080251740
Abstract: An optical heterodyne sampling device includes: two pulsed laser sources which may have a jitter and which can receive respectively a pump beam and a probe beam having respective repetition frequencies Fs and Fp; and an element for combining the pump beam and the probe beam which are intended to be passed over a sample, consisting of a signal channel including a system for the photodetection of the response signal from the sample and a system for acquiring the photodetected signal, which is connected to the signal channel. According to the invention, Fs and Fp are essentially constant and the acquisition system includes an acquisition trigger element. A synchronization channel is connected to the trigger element, and includes a device for measuring the beat frequency |Fs-Fp| which can generate a synchronization signal comprising pulses each time the pulses of the pump beam and the probe beam coincide.


Curriculum vitae

Curriculum vitae


Head of the Ultra Fast and Nanoscale Energy Transfer  aka TIPI research group at LOMA



Université Paris X                  Electrical Engineering                         B. Tech, 1988

Université Bordeaux 1        Electrical Engineering                         M.S., 1990

Electrical & Optical Engineering     PhD, 1994

HDR 2001.


Professor, University of Bordeaux                                                    Dec 08 to present




Post-Doc and PhD offers

Post-Doc title Ultrafast Thermal Imaging at the Nanoscale

Research project

(18 months)

Context: Heat transfer and energy conversion at the nanoscale has been a prominent issue for a multitude of nanotechnology applications. Currently, there are three remaining problems. First, despite a very significant experimental effort, a comprehensive theoretical description of the hot carrier generation process is still missing. The second is the administration and conduction of heat produced inside nanotechnology devices to preserve the performance and the reliability of their components. Third is actually using nanotechnology to control the flow of heat as well as its conversion into energy. These issues arise in areas such as thermo-photovoltaics, integrated circuits, semiconductor lasers or integrated optics.
The transfer of heat at nanoscale distances is believed to be much more different than that of the micro- and macro-scales. When a structure or device length approaches nanoscale distances, classical laws are no longer valid; new techniques and calculations have to be carried out. Just as Ohm’s law is ironclad for electrical conductors, Fourier’s law can be seen as the empirical rule of heat transfer in solids. Fourier’s law states that thermal conductivity is independent of sample length, and tends to be violated when reaching low dimensional in nanoscale systems.
Heat transport is not yet well understood neither from nano-scale to macro-scale nor from femtosecond to nanosecond time scales. This project will generate unique experimental devices to amplify the impact of multicarrier energy transport at nanoscale.
Light is an ideal tool to produce nanometric hot spots. Light can easily be highly confined in nanospace, and the optical field is locally enhanced when plasmons are excited in nanostructures. The properties of the local optical fields near the metal nanostructures are strongly influenced by the spatial and temporal characteristics of plasmons, thus, the direct observation of the spatiotemporal behaviour of plasmons is of fundamental importance. The spatial scale of plasmons in metal nanostructures is essentially smaller than the diffraction limit of light (a few hundred nanometers), and the time scale of plasmon dynamics is faster than the rapid dephasing process in the range of few femtoseconds to 20 fs. Therefore, we will simultaneously carry out, via plasmonic excitation, high spatial and temporal confinement to further understand the fundamental mechanisms of heat transfer.
A combination of near field technique with Time Domain Thermoreflectance has the potential to achieve nanometer and femtosecond spatiotemporal resolution, the presently proposed technique has, to our knowledge, never been reported in the literature.Project: This project aims to use an AFM and femtosecond pump-probe thermoreflectance for the design of a time resolved (femtosecond) NSOM bench.
One issue is the understanding of the interactions between the NSOM tip, the sample and the femtosecond laser.
Initially, the project will start by carrying out measurements of thermal properties on nano-structures by SThM and femtosecond pump-probe. A second step will consist in performing NSOM measurements resolved in time and space on these same structures.Position summaryFull-time temporary researcher position. The position is a 1+1-year contract (1 year extendable once for a total of 24 months) as a post-doc. Qualifications: A PhD degree or a previous post-doc in micro and nano heat transfer, expertise in practical experience in near field microscopy and/or femtosecond spectroscopy.


  • The candidate should have familiarity and some practical use of software environment (LabView, Matlab),
  • Business level English proficiency is mandatory,
  • Previous hands-on laboratory experience is desirable,
  • Ability to work well in a team/support environment is required,

Fields of expertise: Heat transfer, thermal characterisation methods. 

Our offer to you: The university is located at 15min from the centre of  Bordeaux labelled as a “City of Art and History” and listed as a “Word Heritage Site” by UNESCO, opened a place dedicated to its heritage, the history of the city and major urban projects. We also offer an attractive salary, health insurance. 

Application procedure: The application should be written in French or English and sent electronically as a single PDF file containing the following documents: 

CV including: 
–  Complete list of publications, 
–  Two references that we can contact. 

Cover letter, 1-2 pages where you describe: 
–  Yourself and present your qualifications, 
–  Your motivation for the position
–  Future goals and research focus.

To Stefan Dilhaire ( and 
Stéphane Grauby (

Starting date:

Name of the Post-Doc advisor(s) Stefan Dilhaire:, 05 40 00 27 86

Stéphane Grauby:, 05 40 00 25 09

Group Ultra Fast and NanoScale Energy Transport
List of the partners (lab/company/univ.) CNRS, Université Paris Sud, Paris-Saclay.


Post-Doc title

Research project

Name of the Post-doc advisor(s)

(E-mail, Tel)

Stefan Dilhaire,, 05 4000 2786
Group Ultra Fast and NanoScale Energy Transport
List of the partners (lab/company/univ.)




Laboratoire Ondes et Matière d’Aquitaine
351 cours de la libération
33405 Talence Cedex

Phone : + 33 (0)5 40 00 27 86