Chalcogenide glass fibers based on sulfide, selenide, telluride and their rare earth doped compositions are being actively investigated worldwide. Great strides have been made in reducing optical losses using improved chemical purification techniques, but further improvements are needed in both purification and fiberization technology to attain the theoretical optical losses. Despite these problems, current single mode and multimode chalcogenide glass fibers are enabling numerous applications. Some of these applications include laser power delivery, chemical sensing, imaging, scanning near field microscopy/spectroscopy, fiber IR sources/lasers, amplifiers and optical switches. The authors assert that the research and development of chalcogenide glasses will grow in the foreseeable future, especially with respect to improvements in the optical quality of the fibers and the performance of the fibers in existing and future applications.

Active and passive chalcogenide glass optical fibers for IR applications: a review

The author provides an update of: glass preparation in bulk, fibre and film form; optical and thermal properties, and potential applications of chalcogenide glasses.

Chalcogenide glasses: a review of their preparation, properties and applications

High index-contrast fiber waveguides, materials for forming high index-contrast fiber waveguides, and applications of high index-contrast fiber waveguides are disclosed.

High index-contrast fiber waveguides and applications

The data on the present degree of purity of chalcogenide glasses for fiber optics, on their methods of production and on the properties, which are essential for their actual application, are generalized. The content of limiting impurities in the best samples of chalcogenide glasses is 10–100 ppb wt.; of heterophase inclusions with size of about 100 nm is less than 103 cm−3. On the basis of chalcogenide glasses the multimode and single mode optical fibers are produced with technical and operation characteristics sufficient for a number of actual applications. The minimum optical losses of 12–14 dB/km at 3–5 µm are attained in the optical fiber from arsenic-sulfide glass. The level of losses in standard chalcogenide optical fibers is 50–300 dB/km in 2–9 µm spectral range. The factors, affecting the optical absorption of glasses and optical fibers, are analyzed, and the main directions in further development of chalcogenide glasses as the materials for fiber optics are considered.

High-purity chalcogenide glasses for fiber optics

Applications of chalcogenide glass optical fibers

Sulfide, selenide and telluride glass fibers were prepared for infrared optical applications. A new crucible drawing method was developed for the drawing of fibers with glass cladding. The extrinsic losses caused by some oxide impurities were suppressed by the purification of raw elements. The transmission loss and mechanical strength, i.e., bending and tensile, of each fiber were investigated before and after the heat treatment under humid conditions. The fibers obtained were used for the power delivery of CO2 laser (10.6 μm) and CO laser (5.4 μm). The antireflection coating onto fiber ends and cooling of fiber with gas or water were examined for the improvement of power transmission efficiency. A fiber cable having ZnSe lens at the output end was prepared for medical and other applications. Temperature monitoring, thermal imaging and gas sensing were also tried using the fibers.

Recent advances and trends in chalcogenide glass fiber technology: a review

GeAsSeTe, GeSeTeTl, and GeSeTe glass fibers with a core-cladding structure were prepared by one of two methods: crucible drawing or preform drawing. The diameter of the core was 340 microm and that of the cladding was 440 microm. The transmission loss spectra of the fibers were measured by the cut-back method. The crucible drawing method was preferable to reduce the loss due to structural imperfections at the interface of the core and cladding. The lowest loss of 1.7 dB/m was achieved at 10.6 microm (the wavelength of the CO(2) laser) in the fibers with a GeSeTe core and a GeAsSeTe cladding. Transmission of CO(2) laser power was examined using a 1.5-m long fiber and an output power of 2 W (2.2 kW/cm(2) in power density) was obtained.

Chalcogenide glass fiber with a core–cladding structure

Coherent infrared (IR) image bundle was developed for the delivery of the IR thermal image. The fiber employed was the As2S3 glass core of 65 μm diam and Teflon (perfluoronated ethylene propylene) cladding of 75 μm diam, which has the transmission range in the wavelength region between 1 and 7 μm. Two kinds of bundles of 100 cm long were prepared, which consisted of 1550 fibers (NPB75‐1550) and of 8400 fibers (NPB75‐8400). The IR imaging system was constructed by coupling the bundle to an IR television camera. The performance of the system was investigated by detecting the thermal image of an operating LSI package.

Coherent infrared fiber image bundle

PURPOSE: To obtain Tl-containing optical glass suitable as lenses of refractive index gradient type, comprising SiO 2 , Al 2 O 3 , Tl 2 O and MgO as main components and specifying the ratio of these components and an alkali metal. CONSTITUTION: Optical glass comprising 50W75mol.% SiO 2 , 8.5W20mol.% Al 2 O 3 , 0.5W15mol.% Tl 2 O and 2W20mol.% MgO as main components, 12W30mol.% Tl 2 O+R 2 O (R is alkali metal) in the ratio of (Tl 2 O+R 2 O)/Al 2 O 3 ≥1.25. A composition comprising 50W75mol.% SiO 2 , 8.5W20mol.% Al 2 O 3 , 0.5W15mol.% Tl 2 O, 0W25mol.% R 2 O, 2W20mol.% MgO, 0W10mol.% CaO, 0W10mol.% ZnO, 0W5mol.% B 2 O 3 , 0W5mol.% SrO, 0W5mol.% BaO, 0W5mol.% PbO, 0W7mol. TiO 2 , 0W2mol.% ZrO 2 and a clarifier may be cited as the preferable composition for the optical glass. COPYRIGHT: (C)1988,JPO&Japio

Thallium-containing optical glass

Chalcogenide Ge-As-Se-Te glasses for infrared fiber have been investigated. The extent of the glass forming region, the thermal properties and the infrared transmissions are reported. The glasses were purified by the distillation method containing Mg getter to remove oxide absorption peaks. The fibers were fabricated by the crucible method using high purified glasses and their transmission loss spectra were measured in a wavelength region 3–13 μm. The lowest transmission loss at 10.6 μm obtained is 1.5 dB/m. In the glass system, the appropriate Te content for low-loss fiber at 10.6 μm was found in the vicinity of 50 atomic %.

Takashi Yamagishi

Papers

Recent advances and trends in chalcogenide glass fiber technology: a review

Chalcogenide glass fiber with a core–cladding structure

Coherent infrared fiber image bundle

Thallium-containing optical glass

Optical and thermal properties of chalcogenide Ge-As-Se-Te glasses for IR fibers