F. Smektala

Non-linear optical properties of chalcogenide glasses measured by Z-scan

Abstract To explore the potentialities of chalcogenide glasses for ultrafast optical switching, the non-linear refractive indices of different compositions are measured. Several binary glasses in the [Ge–Se] system, As2S3 and As2Se3 glasses, as well as ternary glasses in the [Ge–Se–As] system have been characterized. Non-linear measurements have been performed by the Z-scan technique, at different intensities, with the picosecond pulses emitted by a 10 Hz Q-switched mode-locked Nd-YAG laser at 1064 nm, in adequate conditions to characterize ultrafast non-linearities. Non-linear refractive indices as high as 22×10 −18 m 2 / W have been obtained in the ternary system. In the case of As2S3 and As2Se3 glasses, a significant variation of the value of the non-linear index of refraction with the laser intensity has been observed which is attributed to a fifth order non-linearity.

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 0.7 dB/m or 0.35 dB/m according to the MOF core size. The fibers have been designed to present a zero dispersion wavelength (ZDW) around 2 microm. By pumping the fibers at 1.55 microm, strong spectral broadenings are obtained in both 1.8 and 45-m-long fibers by using a picosecond fiber laser.

Microstructured chalcogenide optical fibers from As2S3 glass: towards new IR broadband sources

The aim of this paper is to present an overview of the recent achievements of our group in the fabrication and optical characterizations of As(2)S(3) microstructured optical fibers (MOFs). Firstly, we study the synthesis of high purity arsenic sulfide glasses. Then we describe the use of a versatile process using mechanical drilling for the preparation of preforms and then the drawing of MOFs including suspended core fibers. Low losses MOFs are obtained by this way, with background level of losses reaching less than 0.5 dB/m. Optical characterizations of these fibers are then reported, especially dispersion measurements. The feasibility of all-optical regeneration based on a Mamyshev regenerator is investigated, and the generation of a broadband spectrum between 1 µm and 2.6 µm by femto second pumping around 1.5 µm is presented.

Experimental and theoretical study of higher-order nonlinearities in chalcogenide glasses

Abstract We investigate experimentally and theoretically the nonlinear properties of two distinct chalcogenide glasses. Nonlinearities are measured through a spatially resolved Mach–Zehnder interferometer. It is shown that the resulting nonlinear index coefficient cannot be correctly described with the usual cubic model. A more convenient theory is developed assuming a medium with two-photon nonlinear absorption and both cubic ( n 2 ) and quintic ( n 4 ) nonlinear index variations. The resulting closed-form expression for the effective nonlinear index coefficient allows to extract the cubic and quintic index coefficients.

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.

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 0.4 dB/m at 1.55 µm and less than 0.05 dB/m in the mid IR. Various As(38)Se(62) chalcogenide microstructured fibers have been prepared in order to combine large non linear index of these glasses with the mode control offered by MOF structures. Small core fibers have been drawn to enhance the non linearities. In one of these, three Stokes order have been generated by Raman scattering in a suspended core MOF pumped at 1995 nm.

Mid-infrared 2000-nm bandwidth supercontinuum generation in suspended-core microstructured Sulfide and Tellurite optical fibers

In this work, we report the experimental observation of supercontinua generation in two kinds of suspended-core microstructured soft-glass optical fibers. Low loss, highly nonlinear, tellurite and As2S3 chalcogenide fibers have been fabricated and pumped close to their zero-dispersion wavelength in the femtosecond regime by means of an optical parametric oscillator pumped by a Ti:Sapphire laser. When coupled into the fibers, the femtosecond pulses result in 2000-nm bandwidth supercontinua reaching the Mid-Infrared region and extending from 750 nm to 2.8 µm in tellurite fibers and 1 µm to 3.2 µm in chalcogenide fibers, respectively.

Second-harmonic generation of thermally poled chalcogenide glass.

Second harmonic generation (SHG) has been obtained in a sample of Ga5Ge20Sb10S65 glass submitted to a thermal poling treatment. An original characterization method is used for the determination of the induced second-order nonlinear profile. A reproducible chi(2) susceptibility of 4.4 +/- 0.4 pm/Volt was achieved for specific poling conditions.

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.

Solid state 77Se NMR investigations on arsenic-selenium glasses and crystals

Abstract Some resolved solid state 77 Se NMR spectra are presented in the As x Se 1− x glass family at ambient temperature. They exhibit three different kinds of Se environments. A comparison with the parent crystalline phases permits to assign the lines to Se- Se -Se, Se- Se -As and As- Se -As Se atom neighborhoods. The measurements of the relative intensities of the lines prove the validity of the intermediate range order structural model known as the “chains crossing model” which is based on AsSe 3 pyramids homogeneously distributed among the divalent Se atoms network. In particular, any scenario involving a selenium clustering process is refuted.