Surface Functionalization with Polymer Membrane or SEIRA Interface to Improve the Sensitivity of Chalcogenide-Based Infrared Sensors Dedicated to the Detection of Organic Molecules.

Priority substances likely to pollute water can be characterized by mid-infrared spectroscopy based on their specific absorption spectral signature. In this work, the detection of volatile aromatic molecules in the aqueous phase by evanescent-wave spectroscopy has been optimized to improve the detection efficiency of future optical sensors based on chalcogenide waveguides. To this end, a hydrophobic polymer was deposited on the surface of a zinc selenide prism using drop and spin-coating methods.

Complete design of a fully integrated graphene-based compact plasmon coupler for the mid-infrared.

A fully integrated waveguide-based, efficient surface plasmon coupler composed of a realistic non-tapered dielectric waveguide with graphene patches and sheet is designed and optimized for the infrared. The coupling efficiency can reach nearly 80% for a coupler as short as 700 nm for an operating wavelength of 12 m. This work is carried out using rigorous numerical models based on the finite element method taking into account 2D materials as surface conductivities.

Discontinuities in photonic waveguides: rigorous Maxwell-based 3D modeling with the finite element method.

In this paper, a general methodology to study rigorous discontinuities in open waveguides is presented. It relies on a full vector description given by Maxwell's equations in the framework of the finite element method. The discontinuities are not necessarily small perturbations of the initial waveguide and can be very general, such as plasmonic inclusions of arbitrary shapes.

Linear and nonlinear optical properties of co-sputtered Ge-Sb-Se amorphous thin films.

Amorphous Ge-Sb-Se thin films were co-sputtered from ${{\rm GeSe}_4}$GeSe and ${{\rm Sb}_2}{{\rm Se}_3}$SbSe targets. Depending on the film composition, linear optical properties were studied by ellipsometry. The Kerr coefficient and two-photon absorption coefficient were estimated using Sheik-Bahae's formalism for co-sputtered films of ${{\rm GeSe}_4} {\text -} {\rm Sb}_2{{\rm Se}_3}$GeSe-SbSe compared to ${{\rm GeSe}_2}{\text -}{\rm Sb}_2{{\rm Se}_3}$GeSe-SbSe pseudo-binary system and ${{\rm As}_2}{{\rm Se}_3}$AsSe as reference.

Effect of cladding geometry on resonant coupling between fundamental and cladding modes in twisted microstructured fibers.

We analyzed for the first time the effect of variations in the number of air hole rings and the filling factor of twisted microstructured optical fibers on the resonant couplings between fundamental and cladding modes. Rigorous numerical simulations show that these parameters can be used to control the spectral width of the resonance peaks, resonance loss, and relative strength of polarization effects. Furthermore, the number of air hole rings has a decisive impact on the number of twist-induced resonances and their wavelength range.

Exact calculation of the nonlinear characteristics of 2D isotropic and anisotropic waveguides.

We use our vector Maxwell's nonlinear eigenmode solver to study the stationary solutions in 2D cross-section plasmonic slot waveguides with isotropic Kerr nonlinear codes and anisotropic Kerr nonlinear cores. First, for the isotropic case, we demonstrate that, even in the low-power regime, 1D studies may not provide accurate and meaningful results compared to 2D ones. Second, we study, including at high powers, the link between the nonlinear parameter γ and the change of the nonlinear propagation constant Δβ.

Improved nonlinear slot waveguides using dielectric buffer layers: properties of TM waves.

We propose an improved version of the symmetric metal slot waveguides with a Kerr-type nonlinear dielectric core adding linear dielectric buffer layers between the metal regions and the core. Using a finite element method to compute the stationary nonlinear modes, we provide the full phase diagrams of its main transverse magnetic modes as a function of the total power, buffer layer, and core thicknesses that are more complex than the ones of the simple nonlinear metal slot. We show that these modes can exhibit spatial transitions toward specific modes of the new structure as a function of power.

Photonic Bandgap Propagation in All-Solid Chalcogenide Microstructured Optical Fibers.

An original way to obtain fibers with special chromatic dispersion and single-mode behavior is to consider microstructured optical fibers (MOFs). These fibers present unique optical properties thanks to the high degree of freedom in the design of their geometrical structure. In this study, the first all-solid all-chalcogenide MOFs exhibiting photonic bandgap transmission have been achieved and optically characterized.

All-solid all-chalcogenide microstructured optical fiber.

The realization of an all-solid microstructured optical fiber based on chalcogenide glasses was achieved. The fiber presents As(2)S(3) inclusions selected as low refractive index material (n = 2.4) embedded in a As(38)Se(62) glass matrix (n = 2.

Low-power plasmon-soliton in realistic nonlinear planar structures.

We study the propagation of nonlinear waves in layered nonlinear dielectric/linear dielectric/metal planar structures. We develop vector models that describe the light propagation in such configurations and allow us to obtain both one- and two-dimensional solutions. We compute the nonlinear dispersion relation and the field profiles, and estimate losses.

Fourth-order cascaded Raman shift in AsSe chalcogenide suspended-core fiber pumped at 2 μm.

Cascaded Raman wavelength shifting up to the fourth order ranging from 2092 to 2450 nm is demonstrated using a nanosecond pump at 1995 nm in a low-loss As(38)Se(62) suspended-core microstructured fiber. These four Stokes shifts are obtained with a low peak power of 11 W, and only 3 W are required to obtain three shifts. The Raman gain coefficient for the fiber is estimated to (1.

Low loss microstructured chalcogenide fibers for large non linear effects at 1995 nm.

Microstructured optical fibers (MOFs) are traditionally prepared using the stack and draw technique. In order to avoid the interfaces problems observed in chalcogenide glasses, we have developed a new casting method to prepare the chalcogenide preform. This method allows to reach optical losses around 0.

Casting method for producing low-loss chalcogenide microstructured optical fibers.

We report significant advances in the fabrication of low loss chalcogenide microstructured optical fiber (MOF). This new method, consisting in molding the glass in a silica cast made of capillaries and capillary guides, allows the development of various designs of fibers, such as suspended core, large core or small core MOFs. After removing the cast in a hydrofluoric acid bath, the preform is drawn and the design is controlled using a system applying differential pressure in the holes.

Strong infrared spectral broadening in low-loss As-S chalcogenide suspended core microstructured optical fibers.

We report the fabrication and characterization of the first guiding chalcogenide As(2)S(3) microstructured optical fibers (MOFs) with a suspended core. At 1.55 microm, the measured losses are approximately 0.

Te-As-Se glass microstructured optical fiber for the middle infrared.

We present the first fabrication, to the best of our knowledge, of chalcogenide microstructured optical fibers in Te-As-Se glass, their optical characterization, and numerical simulations in the middle infrared. In a first fiber, numerical simulations exhibit a single-mode behavior at 3.39 and 9.

Small-core chalcogenide microstructured fibers for the infrared.

We report several small-core chalcogenide microstructured fibers fabricated by the "Stack & Draw" technique from Ge(15)Sb(20)S(65) glass with regular profiles. Mode field diameters and losses have been measured at 1.55 microm.

Antiresonant reflecting optical waveguide microstructured fibers revisited: a new analysis based on leaky mode coupling.

Using two different modal methods, the multipole method and the more recent fast Fourier factorization method, we exhibit and explain a core mode transition induced by avoided crossing between a core localized leaky mode and an high-index cylinder leaky mode in anti-resonant reflecting optical waveguide microstructured optical fibers (ARROW MOFs). Due to its wavelength selectivity and to the leaky nature of the involved modes, this transition doesn't seem to have already been described in detail and analyzed as done in this work in spite of several already published studies on core mode dispersion properties. The main properties of this transition are also described.

Accurate measurement of the cutoff wavelength in a microstructured optical fiber by means of an azimuthal filtering technique.

A simple self-referenced nondestructive method is proposed for measuring the cutoff wavelength of microstructured optical fibers (MOFs). It is based on the analysis of the time-dependent optical power transmitted through a bow-tie slit rotating in the far-field pattern of the fiber under test. As a first demonstration, the cutoff wavelength of a 2 m MOF sample is found to be close to that provided by numerical predictions (approximately 25 nm higher).

Diffraction theory: application of the fast Fourier factorization to cylindrical devices with arbitrary cross section lighted in conical mounting.

The differential theory of diffraction by arbitrary cross-section cylindrical objects is developed for the most general case of an incident field with a wave vector outside the cross-section plane of the object. The fast Fourier factorization technique recently developed for studying gratings is generalized to anisotropic and/or inhomogeneous media described in cylindrical coordinates; thus the Maxwell equations are reduced to a first-order differential set well suited for numerical computation. The resolution of the boundary-value problem, including an adapted S-matrix propagation algorithm, is explained in detail for the case of an isotropic medium.

Fabrication of complex structures of Holey Fibers in Chalcogenide glass.

We report recent progress on fabrication of solid core microstructured fibers in chalcogenide glass. Several complex and regular holey fibers from Ga5Ge20Sb10S65 chalcogenide glass have been realized. We demonstrate that the "Stack & Draw" procedure is a powerful tool against crystallisation when used with a very stable chalcogenide glass.

Second mode transition in microstructured optical fibers: determination of the critical geometrical parameter and study of the matrix refractive index and effects of cladding size.

We carried out a numerical study of the second mode transition in finite-sized, microstructured optical fibers (MOFs) for several values of the matrix refractive index. We determined a unique critical geometrical parameter for the second mode cutoff that is valid for all the matrix refractive indices studied. Finite size effects and extrapolated results for infinite structures are described.

Dispersion management with microstructured optical fibers: ultraflattened chromatic dispersion with low losses.

We numerically demonstrate ultraflattened chromatic dispersion with low losses in microstructured optical fibers (MOFs). We propose using two different MOF structures to get this result. Both structures are based on a subset of a triangular array of cylindrical air holes; the cross sections of these inclusions are circular, and a missing hole in the fiber's middle forms the core.

Chromatic dispersion and losses of microstructured optical fibers.

Using a rigorous and vector multipole method, we compute both losses and dispersion properties of microstructured optical fibers with finite cross sections. We restrict our study to triangular lattices of air-hole inclusions in a silica matrix, taking into account material dispersion. The fiber core is modeled by a missing inclusion.

Microstructured optical fibers: where's the edge?

We establish that Microstructured Optical Fibers (MOFs) have a fundamental mode cutoff, marking the transition between modal confinement and non-confinement, and give insight into the nature of this transition through two asymptotic models that provide a mapping to conventional fibers. A small parameter space region where neither of these asymptotic models holds exists for the fundamental mode but not for the second mode; we show that designs exploiting unique MOF characteristics tend to concentrate in this preferred region.