Samuel Heidmann

National Institute for Research in Computer Science and Control | INRIA · SED- Service Expérimentation et Développement

In a Fourier Transform spectrometer, the main issue is to sample an interferogram with a small spatial step and over a large number of fringe periods resulting in a long sampling distance. The first condition is linked to the spectral etendue or the wavelength range to analyze, whereas the second one is linked to the spectral resolution achievable....

Mid-infrared wideband modulation (3.2–3.7 μm) is achieved in an electro-optic Y-junction using lithium niobate waveguides in TE polarized light. Comparison between external (scanning mirror) and internal (electro-optical) modulation allows studying the chromatic polynomial dependence of the relative phase. Internal modulation consists on a V AC ram...

The identification and characterization, at the cellular level, of cytokine productions present a high interest for both fundamental research and clinical studies. However, the majority of techniques currently available (ELISA, ELISpot, flow cytometry, etc.) have several shortcomings including, notably, the assessment of several cytokines in relati...

In this work, we propose an alternative to the sub-sampling limitation in the single-waveguide configuration of SWIFTS technology using the electro-optical properties of Lithium Niobate (LiNbO3) technology. A Mach-Zehnder intensity modulator, with an initial imbalance between the arms, is coupled with a linear SWIFTS-Lippmann spectrometer. With qui...

Integrated optics spectrometers can be essentially classified into two main families: based on Fourier transform or dispersed modes. In the first case, an interferogram generated inside an optical waveguide is sampled using nanodetectors, these scatter light into the detector that is in contact with the waveguide. A dedicated FFT processing is need...

High-resolution spectrometers are nowadays achievable in compact devices using integrated optics. The approach developed here consists in obtaining a static interferogram by means of a Fresnel reflection at the waveguide output (Lippmann interference between forward and backward beams) and then sample the fringes by periodically etching the wavegui...

The context of this work is the development of integrated optic beam combiners devoted to high contrast interferometry, in particular for exoplanet spectral characterization and future spatial missions, where the use of compact and light optical beam combiners ensures robustness and stability of the interferometric signal. Thus, the development of...

The idea behind FIRST (Fibered Imager foR a Single Telescope) is to use single-mode fibers to combine multiple apertures in a pupil plane as such as to synthesize a bigger aperture. The advantages with respect to a pure imager are i) relaxed tolerance on the pointing and cophasing, ii) higher accuracy in phase measurement, and iii) availability of...

We present an optimization process to improve the rejection ratio in integrated beam combiners by locking the dark fringe and then monitoring its intensity. The method proposed here uses the electro-optic effect of lithium niobate in order to lock the dark fringe and to real-time balance the photometric flux by means of a two-stage Mach–Zehnder int...

The observation of exoplanets and more generally of the close environment of young stars represents an observational double difficulty : the small angular separation between the star and the planet (or its environment such as a protoplanetary disk) and contrast flux. One technique to overcome these difficulties is the nulling interferometry. Two te...

Double polarization electro-optic beam combiners based on a Ti:diffusion lithium niobate waveguide have been developed for mid-infrared applications. A monochromatic rejection ratio of up to 33 dB at λ = 3.39 μm was obtained, as well as wideband fringes showing low dispersion. In a first part, studying the fringe contrast as a function of waveguide...

We present our work on integrated optic beam combiners devoted to mid-infrared applications in the field of stellar interferometry, in particular for nulling interferometry, where high rejection ratios are needed. The main results obtained are the single-mode behavior of the waveguides at a central wavelength λ=3.39μm, in both TE and TM polarizatio...

We present mid-infrared active beam combiners based on Ti:diffused Lithium Niobate waveguides. Y-junction rejection ratio is studied at 3.39um and 4.87um and compared to the 40dB required in exoplanet research programs using nulling interferometry

Lithium Niobate (LN) based electro-optic modulators are well known in the optical communications field, due to their high bandwidth and deep rejection ratio [1]. These performances could be used in the field of astronomy for stellar interferometry in the mid-infrared domain [2]. With our partners from Photline Technologies, we have conceived, devel...

We propose a new optical architecture for the laser optical feedback imaging (LOFI) technique which makes it possible to avoid the adverse effect of the optical parasitic backscattering introduced by all the optical interfaces located between the laser source and the studied object. This proposed setup needs no specific or complex alignment, which...