Patrick Houizot

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. Fiber losses, which are the lowest recorded so far for selenium based MOFs, are equal to the material losses, meaning that the process has no effect on the glass quality.

Linear and Nonlinear Characterizations of Chalcogenide Photonic Crystal Fibers

In this paper, we investigate the linear and nonlinear properties of GeSbS and AsSe chalcogenide photonic crystal fibers. Through several experimental setups, we have measured the second- and third-order chromatic dispersion, the effective area, losses, birefringence, the nonlinear Kerr coefficient as well as Brillouin and Raman scattering properties.

Chalcogenide Microstructured Fibers for Infrared Systems, Elaboration Modelization, and Characterization

Abstract Chalcogenide fibers present numerous possible applications in the IR field. For many applications, single mode fibers must be obtained. An original way is the realization of microstructured optical fibers (MOFs) with solid core. These fibers present a broad range of optical properties thanks to the high number of freedom degrees of their geometrical structure. In this context, we have developed MOFs for near and mid IR transmission with different geometries and properties such as multimode or endless single-mode operation, small or large mode area fibers. We have also investigated numerically the main linear properties of such MOFs.

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 9.3 microm, in good agreement with experimental near-field captures at 9.3 microm. The second fiber is not monomode between 3.39 and 9.3 microm, but the fundamental losses are 9 dB/m at 3.39 microm and 6 dB/m at 9.3 microm. The experimental mode field diameters are compared to the theoretical ones with a good accordance.

Shaping of looped miniaturized chalcogenide fiber sensing heads for mid-infrared sensing.

Chalcogenide glass fibers are promising photonic tools to develop Fiber Evanescent Wave Spectroscopy (FEWS) optical sensors working in the mid-infrared region. Numerous pioneering works have already been carried out showing their efficiency, especially for bio-medical applications. Nevertheless, this technology remains confined to academic studies at the laboratory scale because chalcogenide glass fibers are difficult to shape to produce reliable, sensitive and compact sensors. In this paper, a new method for designing and fabricating a compact and robust sensing head with a selenide glass fiber is described. Compact looped sensing heads with diameter equal to 2 mm were thus shaped. This represents an outstanding achievement considering the brittleness of such uncoated fibers. FEWS experiments were implemented using alcoholic solutions as target samples showing that the sensitivity is higher than with the routinely used classical fiber. It is also shown that the best compromise in term of sensitivity is to fabricate a sensing head including two full loops. From a mechanical point of view, the breaking loads of the loop shaped head are also much higher than with classical fiber. Finally, this achievement paves the way for the use of mid-infrared technology during in situ and even in vivo medical operations. Indeed, is is now possible to slide a chalcogenide glass fiber in the operating channel of a standard 2.8 mm diameter catheter.

Experimental investigation of Brillouin and Raman scattering in a 2SG sulfide glass microstructured chalcogenide fiber.

In this work, we investigate the Brillouin and Raman scattering properties of a Ge15Sb20S65 chalcogenide glass microstructured single mode fiber around 1.55 microm. Through a fair comparison between a 2-m long chalcogenide fiber and a 7.9-km long classical single mode silica fiber, we have found a Brillouin and Raman gain coefficients 100 and 180 larger than fused silica, respectively.

Advances in the elaboration of chalcogenide photonic crystal fibers for the mid infrared

Chalcogenide glasses present several original properties when being compared to the reference silica glass. They are very non linear, hundred to thousand times more non linear than the standard silica, they are very transparent in the infrared, until 10 μm to 20 μm depending on their composition, and they can be drawn into optical fibers. Thus, the case of chalcogenide photonic crystal fibers (PCF) is of particular interest. Indeed, the effective modal area is adjustable in PCF thanks to geometrical parameters. Then chalcogenide microstructured fibers with small mode area could lead to huge non linear photonic devices in the infrared by the combination of the intrinsic non linearity of these glasses with the non linearity induced by the PCF. Chalcogenide photonic crystal fibers offer therefore a great potential for applications in the fields of Raman amplification or Raman lasers and supercontinuum generation in the mid infrared until at least 5 μm. The possibility to design PCF exhibiting a working range in the mid infrared and more specifically in the 1-6 μm wavelength range opens also perspectives in the optical detection of chemical or biochemical species. This contribution presents the advances in the elaboration of such chalcogenide photonic crystal fibers.

Test results of the infrared single-mode fiber for the DARWIN mission

Nulling interferometry is the baseline technique for the DARWIN planet finding mission of the European Space Agency. Using this technique it will be possible to cancel, by destructive interference, the light from the bright star and look directly at its surrounding planets and eventually discover life on them. To achieve this goal wavefront errors need to be reduced to a very high degree in order to achieve the required nulling quality. Such a high wavefront quality can only be achieved with adequate wavefront filtering measures. Single mode fibers in general have excellent mode filtering capabilities, but they were not recently available for the broad infrared wavelength region of Darwin (4-20 um). Within an ESA technology development project, TNO has designed and tested an infrared single mode fiber based on chalcogenide glasses that has been manufactured by the University of Rennes. Several tests are carried out to characterize the materials used and the IR single mode fiber. Far field intensity distribution measurement at 10.6 um reveals the single mode operation of the manufactured fiber. Influence of coating, length, light coupling and bending of the fiber are also investigated.

Evidence and modeling of mechanoluminescence in a transparent glass particulate composite

Mechanoluminescence (ML) of a transparent alkali-phosphate glass composite with SrAl2O4:Eu, Dy particles is reported. Uniaxial compression experiments show the linear dependence of the mechanoluminescence intensity with the mechanical power. A theoretical model, based on the physics of delayed processes (in analogy of viscoelasticity), is proposed. This model accurately predicts the ML intensity changes induced by a complex mechanical loading and provides a convincing description of the mechanoluminescence response.

Fabrication of low losses chalcogenide photonic crystal fibers by molding process

Chalcogenide glasses are known for their large transparency in the mid infrared and their high refractive index (>2). They present also a high non linear refractive index (n2), 100 to 1000 times larger than for silica. An original way to obtain single-mode fibers is to design photonic crystal fibers (PCFs). Until now, chalcogenide PCFs are realized using the stack and draw process. However this technique induces defects, like bubbles, at the capillaries interfaces, causing significant scattering losses. Until now, the best transmission obtained was 3dB/m at 1.55μm. The poor PCF transmission reduces significantly their application potential. So, we present a new efficient method to realize low-loss chalcogenide PCFs. This original method by molding permits to reduce the optical losses down to 1dB/m at 1.55μm and less than 0.5dB/m between 3 and 5μm for an As-Se PCF. Furthermore, this molding method can be used for different compositions. Single mode fibers were realized. Moreover, very small core fibers were realized with this method, obtaining a non linear coefficient of 15 000W-1km-1 with an As-Se PCF. We also observed self phase modulation at 1.55μm on a fiber with a 2.3μm2 mode area.