T. Kohoutek

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.

Embossing of chalcogenide glasses: monomode rib optical waveguides in evaporated thin films

Single-mode optical rib waveguides operating at telecommunication wavelengths are successfully patterned via a hot embossing technique in a thermally evaporated chalcogenide glass thin film on a chalcogenide glass substrate. Ellipsometry is used to measure the refractive index dispersion of the pressed film (As(40)Se(60)) and substrate (Ge(17)As(18)Se(65)).

Enhanced Raman gain of Ge–Ga–Sb–S chalcogenide glass for highly nonlinear microstructured optical fibers

The off-resonance Raman spectra of As2S3, GeS2, Ge25Ga5S70, Ge23As12S65, Ge23Sb12S65, and Ge17Ga4Sb10S69 chalcogenide glasses have been recorded and the corresponding Raman gain coefficients have been calculated in order to evaluate the role of Ge, Ga, Sb, and As on a novel Ge17Ga4Sb10S69 glass proposed for highly nonlinear microstructured optical fibers. We calculated the Raman response functions of As2S3n2=2.3×10−17 m2/W, G∼2.78×10−11 m/W; and Ge17Ga4Sb10S69 n2=1.8×10−17 m2/W, G∼1.57×10−11 m/W glasses. The supercontinuum generation of a three-air-hole Ge17Ga4Sb10S69 fiber was simulated, challenging the properties of a similar fiber design made of As2S3 chalcogenide glass. We calculated the zero dispersion wavelengths of Ge17Ga4Sb10S69 fibers with the core diameters of 1.2, 1.5, and 2.0 μm at λ=1.48, 1.66, and 1.75 μm in comparison with λ=1.60, 1.87, and 1.98 μm obtained for As2S3 fibers.

Effect of cluster size of chalcogenide glass nanocolloidal solutions on the surface morphology of spin-coated amorphous films

Amorphous chalcogenide thin film deposition can be achieved by a spin-coating technique from proper solutions of the corresponding glass. Films produced in this way exhibit certain grain texture, which is presumably related to the cluster size in solution. This paper deals with the search of such a correlation between grain size of surface morphology of as-deposited spin-coated As33S67 chalcogenide thin films and cluster size of the glass in butylamine solutions. Optical absorption spectroscopy and dynamic light scattering were employed to study optical properties and cluster size distributions in the solutions at various glass concentrations. Atomic force microscopy is used to study the surface morphology of the surface of as-deposited and thermally stabilized spin-coated films. Dynamic light scattering revealed a concentration dependence of cluster size in solution. Spectral-dependence dynamic light scattering studies showed an interesting athermal photoaggregation effect in the liquid state.

Kinetics of optically- and thermally-induced diffusion and dissolution of silver in spin-coated As33S67 amorphous films; their properties and structure

The As33S67 amorphous films were prepared by standard spin-coating technique. Prepared films were stabilized in a vacuum and then annealed in inert argon atmosphere. Silver film was deposited on top of As33S67 film by vacuum thermal evaporation technique. The kinetics of optically- and thermally-induced diffusion and dissolution of silver in As33S67 amorphous films prepared by spin-coating technique were measured by optically monitoring the change in thickness of undoped chalcogenide during broadband illumination. Compositions of reaction products and silver diffusion profiles in different stages of the photostimulated process have been determined by Rutherford backscattering spectroscopy. Optical and Raman spectroscopies were used to establish the optical properties and structure of the films.

Visible Light Generation and Its Influence on Supercontinuum in Chalcogenide As2S3 Microstructured Optical Fiber

We demonstrate visible light generation in chalcogenide As2S3 microstructured optical fiber. The generated visible light causes irreversible damage to the fiber core because of the high absorption coefficient of chalcogenide glasses in the visible band. The SCs (supercontinua) are measured in both untapered and tapered As2S3 fibers, no wider SC is obtained in the tapered one. The SC growth is prevented by the visible light generation since the damage to the fiber core decreases the fiber transmission substantially. This effect can be avoided by designing the fiber to enable the pump source to work in single-mode operation.

Soft imprint lithography of a bulk chalcogenide glass

We report on large-surface-area micro-patterning of a bulk chalcogenide glass by a PDMS soft mould. Micrometre-scale (width ~4μm and depth ~0.8 μm) test patterns such as ribs, channels and a lens array are successfully imprinted into the surface of high refractive index As3S7 bulk glass at 225°C without any applied external pressure. The mean-square roughness of the patterned glass surface is in the range 3 – 10 nm. Soft imprinting of bulk chalcogenide glass is an efficient method for reliable fabrication of optical and photonic devices.

In-situ measurement of reversible photodarkening in ion-conducting chalcohalide glass

We report the kinetics of below band-gap light induced photodarkening in (80-x)GeS(2)-20Ga(2)S(3)-xAgI (x = 0 and 20 mol %) bulk chalcogenide glasses by measuring the time evolution of transmission spectra at every 10 milliseconds. The results prove clearly the enhancement of photosensivity upon doping of AgI compound in glasses. It is interesting to find that PD observed in AgI-doped glass totally disappears two hours later after the laser exposing even at room temperature. In significant contrast to 80GeS(2)-20Ga(2)S(3) glass that the metastable part of PD remains for a long time. We expect such a fast auto-recovery property in AgI-doped glass can be utilized for optical signal processing.

On the analogy between photoluminescence and carrier-type reversal in Bi- and Pb-doped glasses

Reaction order in Bi-doped oxide glasses depends on the optical basicity of the glass host. Red and NIR photoluminescence (PL) bands result from Bi(2+) and Bin clusters, respectively. Very similar centers are present in Bi- and Pb-doped oxide and chalcogenide glasses. Bi-implanted and Bi melt-doped chalcogenide glasses display new PL bands, indicating that new Bi centers are formed. Bi-related PL bands have been observed in glasses with very similar compositions to those in which carrier-type reversal has been observed, indicating that these phenomena are related to the same Bi centers, which we suggest are interstitial Bi(2+) and Bi clusters.

Spin-coated Agx(As0.33S0.67)100−x films: preparation and structure

Abstract We report for the first time on the preparation of samples of Ag x (As 0.33 S 0.67 ) 100− x (from x =0 to 25 at.%) amorphous films by a standard spin-coating technique from n -butylamine solution of the glass constituents. Prepared films were stabilized by annealing in a vacuum furnace purged by inert argon atmosphere. The chemical composition of the spin-coated films has been established. Measurements of the chemical and physical properties of prepared films have been carried out using techniques such as UV/VIS/NIR spectroscopy to characterize the optical properties of films, FTIR and Raman spectroscopy to control the embedded organic solvent content in films and to determine the films structure.