Frequency-Resolved Spatial Beam Mapping in Multimode Fibers: Application to Mid-Infrared Supercontinuum Generation

We present a new spatial-spectral mapping technique permitting to measure the beam intensity at the output of a graded-index (GRIN) multimode fiber with sub-nanometric spectral resolution. We apply this method to visualize the fine structure of the beam shape of a sideband generated at 1870 nm by geometric parametric instability (GPI) in a GRIN fiber. After spatial-spectral characterization, we amplify the GPI sideband with a Tm-doped fiber amplifier to obtain a microjoule-scale picosecond pump whose spectrum is finally broadened in a segment of InF3 optical fiber to achieve supercontinuum ranging from 1.7 {\mu}m up to 3.4 {\mu}mComment: 4 pages, 6 Figure

3D time-domain beam mapping for studying nonlinear dynamics in multimode optical fibers

The characterization of the complex spatiotemporal dynamics of optical beam propagation in nonlinear multimode fibers requires the development of advanced measurement methods, capable of capturing the real-time evolution of beam images. We present a new space-time mapping technique, permitting the direct detection, with picosecond temporal resolution, of the intensity from repetitive laser pulses over a grid of spatial samples from a magnified image of the output beam. By using this time-resolved mapping, we provide the first unambiguous experimental observation of instantaneous intrapulse nonlinear coupling processes among the modes of a graded index fiber.Comment: 4 pages, 6 figure

3D time-domain beam mapping for studying nonlinear dynamics in multimode optical fibers

Characterization of the complex spatiotemporal dynamics of optical beam propagation in nonlinear multimode fibers requires the development of advanced measurement methods, capable of capturing the real-time evolution of beam images. We present a new space–time mapping technique, permitting the direct detection, with picosecond temporal resolution, of the intensity from repetitive laser pulses over a grid of spatial samples from a magnified image of the output beam. By using this time-resolved mapping, we provide, to the best of our knowledge, the first unambiguous experimental observation of instantaneous intrapulse nonlinear coupling processes among the modes of a graded index fiber

All-optical switch based on beam cross-cleaning effect in graded-index multimode fiber

We introduce the concept of beam all-optical spatial beam switching in graded-index multimode fibers. This consists of seeding a bell-shaped spatial profile to a laser beam at the output of the fiber by exploiting the nonlinear coupling between the modes of the two input beams. Remarkably, we demonstrate that even a weak-control signal allows for improving the spatial profile of a highly multimode intense signal. The device proposed herein will be easily integrated in state-of-the-art optical networks, and will find application in the fields of space-division-multiplexed telecommunication and of multimode fiber lasers

Three octave visible to mid-infrared supercontinuum generation seeded by multimode silica fiber pumped at 1064 nm

International audienceHyperspectral spectroscopy requires light sources with wide spectral ranges from the visible to the mid-infrared. Here, we demonstrate the first fiber-based mid-infrared supercontinuum covering three octaves of frequency by leveraging 1-µm laser technology. The process consists in spectral broadening of a 1064-nm pump toward 0.48–2.5 µm in a graded-index multimode fiber, followed by a fluoro-indate fiber used to reach deeper into the near infrared (4.3 µm). Finally, an arsenic selenide chalcogenide fiber allows us to reach the 6-µm wavelength region, providing a 0.75–6-µm supercontinuum. We illustrate the potential of this light source by recording mid-infrared absorption spectra of organic compounds

Antibodies Targeting Human Endothelin-1 Receptors Reveal Different Conformational States in Cancer Cells

International audienceThe endothelin axis (endothelins and their receptors) is strongly involved in physiological and pathological processes. ET-1 plays a crucial role in particular in tumor diseases. Endothelin-1 receptors (ETA and ETB) are deregulated and overexpressed in several tumors such as melanoma and glioma. We studied the binding of 24 monoclonal antibodies directed against human ETB receptors (hETB) to different melanoma cell lines. Few of these mAbs bound to all the melanoma cell lines. One of them, rendomab B49, bound to ETB receptors expressed at the surface of human glioma stem cells. More recently, we produced new antibodies directed against human ETA receptor (hETA). Several antibodies have been isolated and have been screened on different tumoral cells lines. As for the mAbs directed against the hETB receptor only some of new antibodies directed against ETA receptor are capable to bind the human tumoral cell lines. Rendomab A63 directed against hETA is one of them. We report the specificity and binding properties of these mAbs and consider their potential use in diagnosis by an in vivo imaging approach

All-Optical Spatial Beam Switching in Multimode Fibers

We propose and experimentally demonstrate a novel approach to spatial all-optical switching, based on beam self-cleaning in nonlinear graded-index multimode opti-cal fibers

Fiber-based source of 200 fs 1.1 µJ pulses at 1560 nm for high harmonic generation in solids

International audienc

Multimode Optical Fiber Beam-By-Beam Cleanup

We introduce and experimentally demonstrate the concept of all-optical beam switching in graded-index multimode optical fibers. Nonlinear coupling between orthogonally polarized seed and signal beams permits to control the spatial beam quality at the fiber output. Remarkably, we show that even a few-mode control beam whose power is about ten times lower than that of the total beam may substantially enhance the quality of an intense, highly multimode signal beam. We propose a simple geometrical representation of the beam switching operation, whose validity is quantitatively confirmed by the experimental mode decomposition of the output beam. All-optical switching of multimode beams may find important applications in high-power beam delivery and fiber lasers