They have a role of support for teams of the laboratory and at the same time of development and maintenance of instruments.
Each member of the cluster works on different projects and closely participates in experimental work:
- N. SAVOIA has two cross-cutting activities: microwave spectroscopy in the MPI team and the femtosecond laser of the laboratory,
- D. BACQUET is working on the establishment of doubled telecom sources with the team Cold Atoms.
- R. HABERT is in charge of the characterization of all types of optical fibers manufactured within the FiberTech Lille platform.
Nunzia SAVOIA's research activity is carried out in the Molecular Physics Interfaces (MPI) team. The team has two Fourier Transform microwave spectrometers (2-20 GHz). With them, it possible to characterize some physicochemical properties of molecules of atmospheric interest. She is mainly interested in biogenic VOCs (volatile organic compounds). These molecules, present in the atmosphere in low concentration, are precursors of aerosols whose concentration increases in case of pollution. The characterization of their properties allows a better understanding of the mechanisms of aerosol formation.
The experimental results obtained with the spectrometers are confronted with ab-initio quantum chemistry calculations to validate the latter and then to deduce the physicochemical parameters of the studied molecules.
Among molecules studied, Nunzia SAVOIA was interested to verbenone and now to limona ketone, an oxidation product of limonene.
Since the broadband spectrum of a molecule typically contains more than one million resolution elements, it must be scanned at high resolution, which requires days of continuous operation. A new technique, known as CP-FTMW (Chirped Pulsed-Fourier Transform Microwave), makes it possible to measure a spectrum of bandwidth up to 10 GHz in a single take of the spectrometer. The team will develop this type of spectrometer to increase, by several orders of magnitude, the speed at which a spectrum can be obtained.
Nunzia SAVOIA is also responsible for the laboratory's femtosecond chain, which is based on the Chirped Pulse Amplification (CPA) technique, introduced in 1985 by D. Strickland and G. Mourou. : ultrashort light pulses are generated at low energy (of the order of nJ) thanks to the use of a mode-locked ultrashort laser oscillator. The pulses thus generated have a high repetition rate (of the order of 100 MHz), they are then lengthened temporally by a dispersive delay line consisting of a pair of diffraction gratings. One or more amplification stages are used to increase the energy of the stretched pulse. After optical amplification, a second pair of gratings recompresses the pulse to the initial duration.
Technical characteristics of the femtosecond chain:
- Ti:Sa laser from Spectra Phycics
- Pulse wavelength: 800 nm
- 3 operating modes: 45fs, 120fs, 2ps
- Energy output: 2 mJ
- Repetition rate: 1 kHz
Micro-structured fibers & fiber lasers
Rémi HABERT is in charge of the characterization of all types of optical fibers (solid, microstructured, hollow-core or double-clad) manufactured within the FiberTech Lille platform. This includes modal analysis, mitigation, chromatic dispersion, group birefringence but also for fibers with "exotic" materials and laser applications that result from it. He also takes care of formatting "Post manufacturing" of fiber components, ranging from polishing, tapering and the development of fiber-specific welds.
1. SEM image of a 1000-hole fiber.
2. White light transmitted in a hollow-core fiber called "Kagome" under an optical microscope.
3. SEM image of a "Solid Bang Gap" fiber with Germanium inclusions.
1. Generation of supercontinuum in a highly nonlinear optical fiber.
2. Injection of a green laser into a peripheral core of a multicore fiber having undergone longitudinal twist during its manufacture.
SigmaCOM-Optical and wireless communication pole (THz).
The vocation of this center of expertise created in 2015 is to explore disruptive technologies such as spatial multiplexing or even the combination of coherent optical technology with wireless transmissions on THz carriers, and this way to support the ever increasing demand. data transmission capacity around the world.
To support such advanced research, this pole is equipped with latest generation coherent optical communications solutions at European level. These solutions integrate several pieces of equipment and form a bench made up of instruments and a software suite.
In its entirety, this bench allows to control the instrumentation, the shaping of pulses, the acquisition and the processing of the signal in order to quantify the quality of transmission in terms of BER, EVM and diagrams of the eye for different modulation formats up to bit rates up to 512 Gb/s.
The equipment can also be used individually in experiments with increased requirements such as the synchronized acquisition of ultra-fast electrical or optical signals (group of sampling oscilloscopes with 4 ATI channels at 70 GHz or 8 channels at 33 GHz) or the generation of complex electrical or optical signals (group of arbitrary function generators with 8 channels at 22 GHz).
This equipment has been funded under the CPER (CIA1 and Photonics for Society) and EQUIPEX FLUX programs. This cluster is supported by a fruitful collaboration of IEMN and PhLAM research teams hosted at IRCICA.
Esben Ravn ANDRESEN Scientific Manager