Frédéric Désévédavy

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.

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.

Fabrication and characterization of step-index tellurite fibers with varying numerical aperture for near- and mid-infrared nonlinear optics

We present an overview of the fabrication process and characterization of tellurite, germanate, and germanate–tellurite step-index fibers with different index contrasts. Several compatible core/cladding glass pairs were first explored for fiber manufacturing under ambient atmosphere. The potential of the resulting waveguides for nonlinear optics is revealed by means of supercontinuum generation experiments using a near-infrared femtosecond fiber laser. Fabrication of the glass preforms was also adapted to dehydration procedures, allowing the drawing of low-OH step-index tellurite fibers. The beneficial impact of glass purification on supercontinuum generation toward the mid-infrared region is confirmed.

Tailoring supercontinuum generation beyond 2 μm in step-index tellurite fibers

We report numerical and experimental demonstrations of flexible group-velocity dispersion regimes in step-index tellurite fibers by fine control of the fiber core diameter. Our simple fiber design allowed us to explore various nonlinear propagation regimes beyond 2 μm, which involved careful control of four-wave mixing processes. Combined with the recent development of 2 μm fiber lasers, we present an easy way to tailor supercontinuum generation and related coherence features in the high-demand 1.5-3.5 μm spectral region.

High repetition rate mid-infrared supercontinuum generation from 1.3 to 5.3 μm in robust step-index tellurite fibers

We demonstrate broadband supercontinuum generation over two infrared octaves, spanning from 1.3 to 5.3 μm, with an output power of 150 mW in robust step-index tellurite fibers with core diameters between 3.5 and 4.3 μm. As a pump source, we use femtosecond mid-IR pulses from a home-built post-amplified optical parametric oscillator tunable between 1.5 and 4.0 μm at a 43 MHz repetition rate. We study the influence of core size, pump wavelength, and fiber length to optimize the spectral bandwidth. A key requirement for efficient spectral broadening is a low and rather flat average anomalous dispersion over a wide spectral range that can be tailored accordingly by changing the fiber core diameter. Numerical simulations based on the generalized nonlinear Schrodinger equation are in good agreement with experimental results.

Compact supercontinuum sources based on tellurite suspended core fibers for absorption spectroscopy beyond 2 μm

We present the experimental development of two compact supercontinuum laser sources based on tellurite suspended core fibers with and without tapering post-processing. The pumping scheme makes use of commercially-available nJ-level femtosecond and picosecond fiber lasers at 1.56 and 2.06 μm respectively. The resulting spectral broadening that occurs in a few tens-of-centimeters of tellurite fiber allows coverage of the convenient molecular fingerprint region between 2 and 3 μm. It is then exploited in a proof-of-principle experiment for methane spectroscopy measurements in the mid-infrared by means of the supercontinuum absorption spectroscopy technique. Experimental results are in fairly good agreement with both numerical simulations of supercontinuum generation and spectroscopic predictions of the HITRAN database.

Nonlinear effects generation in suspended core chalcogenide fibre

In this work we report our achievements in the elaboration and optical characterizations of low-losses suspended core optical fibers elaborated from As2S3 glass. For preforms elaboration, alternatively to other processes like the stack and draw or extrusion, we use a process based on mechanical drilling. The drawing of these drilled performs into fibers allows reaching a suspended core geometry, in which a 2 μm diameter core is linked to the fiber clad region by three supporting struts. The different fibers that have been drawn show losses close to 0.9 dB/m at 1.55 μm. The suspended core waveguide geometry has also an efficient influence on the chromatic dispersion and allows its management. Indeed, the zero dispersion wavelength, which is around 5 μm in the bulk glass, is calculated to be shifted towards around 2μm in our suspended core fibers. In order to qualify their nonlinearity we have pumped them at 1.995 μm with the help of a fibered ns source. We have observed a strong non linear response with evidence of spontaneous Raman scattering and strong spectral broadening.