Showing papers on "Hard-clad silica optical fiber published in 2002"

Plastic optical fiber lasers and amplifiers containing lanthanide complexes.

Abstract: Organic dye-doped polymers have been widely investigated as gain media in solid-state dye lasers. Dye molecules which have large absorption and induced emission cross sections due to allowed π-π transitions are ideal active dopants for the generation and amplification of intense light pulses. However, continuous wave operation is not feasible with organic dyes because of the triplet losses. On the other hand, lanthanide ions that have long metastable state lifetimes are widely used in silica glass-based fiber amplifiers and for both continuous and pulsed lasers. It has been more than 30 years since the first lanthanide lasers were reported.1-3 During this period a wide variety of lanthanide lasers and amplifiers have been investigated, and extensive progress has been made by many researchers. Many reviews have been written concentrating primarily on the physical and chemical properties of lanthanides in many matrices for laser action.4-8 Recently, several books have focused on lanthanide-doped fiber amplifiers for optical communications.9-11 The success of lanthanide-doped fiber amplifiers has inspired thousands of publications and continues to motivate research on the many diverse components that are required in these systems. Optical links are now used primarily in applications such as telecommunications with single-mode silica optical fibers, which have the ability to provide high-bandwidth and long-distance communications. However, as the demand for bandwidth increases in the office and home, it has become increasingly important to develop very low cost optical links that can be readily installed by users. Plastic optical fibers (POF) have received increasing attention because of their clear technical advantages over glass fibers, such as flexibility and a large core diameter, which enables efficient connection and coupling resulting in a low-cost system for a local area network. Recently a low-loss (100 db/km), highbandwidth 5.12 GHz for 100 m transmission graded index plastic optical fiber (GI-POF) has been developed.12 Also, an all fluorinated POF, whose low loss region is extended to the visible and near-infrared, has been successfully prepared.13 Plastic optical fiber amplifiers (POFA) that generate signal light in the visible and near-infrared are potentially important because of their adaptability for POF-based short span optical local distribution networks. This review describes recent progress on plastic optical fiber lasers and amplifiers with lanthanides. We focus especially on the design and selection of plastic optical fiber and chelate materials.

Extruded soft glass photonic crystal fiber for ultrabroad supercontinuum generation

Abstract: We report the fabrication and properties of soft glass photonic crystal fibers (PCF's) for supercontinuum generation. The fibers have zero or anomalous group velocity dispersion at wavelengths around 1550 nm, and approximately an order of magnitude higher nonlinearity than attainable in comparable silica fibers. We demonstrate the generation of an ultrabroad supercontinuum spanning at least 350 nm to 2200 nm using a 1550 nm ultrafast pump source.

High index-contrast fiber waveguides and applications

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

Optical fiber long-period gratings with Langmuir–Blodgett thin-film overlays

Abstract: An overlay material was deposited by the Langmuir–Blodgett technique onto a single-mode optical fiber containing a long-period grating. The long-period grating exhibits characteristic attenuation bands in its transmission spectrum whose central wavelengths were observed to depend on the optical thickness of the overlay material, even for materials that have a refractive index higher than that of silica.

Particle levitation and guidance in hollow-core photonic crystal fiber

Abstract: We report the guidance of dry micron-sized dielectric particles in hollow core photonic crystal fiber The particles were levitated in air and then coupled to the air-core of the fiber using an Argon ion laser beam operating at a wavelength of 514 nm The diameter of the hollow core of the fiber is 20 m A laser power of 80 mW was sufficient to levitate a 5 m diameter polystyrene sphere and guide it through a ~150 mm long hollow-core crystal photonic fiber The speed of the guided particle was measured to be around 1 cm/s

Optical wavelength filtering apparatus with depressed-index claddings

Abstract: An apparatus and a method for separating a light of a first wavelength μ1 from a second wavelength μ2, where μ1<μ2, in a waveguide such as an optical fiber is described. The apparatus includes a core (12) surrounded by a depressed cladding (16), which itself is surrounded by a secondary cladding (18). The core cross-section, the depressed cladding cross-section, the secondary cladding cross-section, and the refractive indices of the core, the depressed cladding and the secondary cladding are selected to produce a fundamental mode cutoff wavelength μc such that μ1<μc<μ2, and produce a high loss at the secondary wavelength μ2. The apparatus can be used as a filter, and amplifier, a laser, or in a nonlinear optical switch.

Evanescent-wave gas sensing using microstructure fiber

Abstract: We report the experimental demonstration of evanescent-wave gas detection with a silica-air microstructure fiber. Detection sensitivity of ~6% of that of direction absorption spectroscopy per equal length has been achieved. 0]

Photonic crystal fiber coupler.

Abstract: Fiber couplers made with photonic crystal fibers (PCF) are reported. Two types of PCF were fabricated by means of stacking a group of silica tubes around a silica rod and drawing them. The fiber couplers were made by use of the fused biconical tapered method. With a fiber that had five hexagonally stacked layers of air holes, a 33/67 coupling ratio was obtained, and with a one-layer four-hole fiber, a 48/52 coupling ratio was obtained. The fabrication processes and the characteristics of the PCFs and the PCF couplers are presented.

Novel techniques for the fabrication of holey optical fibers

Abstract: Recently developed optical fibers rely on an array of air holes in the cladding to confine light to the fiber core as opposed to conventional telecommunications fibers that require a refractive index difference produced by different composition glasses in the core and cladding regions. Holey fibers have been fabricated by drawing an array of tubes stacked around a solid central core. In this paper, we describe a new technique to produce the holes (or pores) in the cladding region. These new fibers have been made by drawing a preform, consisting of a porous outer cladding region surrounding a solid central core region, into a fiber. During the fiber drawing process, the pores initially present in the preform cladding region are drawn into small, long, thin tubular pores. Controlling the dimensions and distribution of the pores in the preform can control the physical dimensions and distribution of the pores in the fiber. In some of the preforms, the porous cladding region in the preform was prepared by sol gel techniques. The preform fabrication process and fiber drawing process used to produce these new holey fibers as well as the results of the morphological study elucidating the size, shape and distribution of the porous phase are presented.

Fiber optic laser-induced breakdown spectroscopy sensor for molten material analysis

Abstract: A fiber optic laser-induced breakdown spectroscopy (LIBS) sensor, including a laser light source, a harmonic separator for directing the laser light, a dichroic mirror for reflecting the laser light, a coupling lens for coupling the laser light at an input of a multimode optical fiber, a connector for coupling the laser light from an output of the multimode optical fiber to an input of a high temperature holder, such as a holder made of stainless steel, and a detector portion for receiving emission signal and analyzing LIBS intensities. In one variation, the multimode optical fiber has silica core and silica cladding. The holder includes optical lenses for collimating and focusing the laser light in a molten alloy to produce a plasma, and for collecting and transmitting an emission signal to the multimode optical fiber.

Coupled optical and optoelectronic devices, and method of making the same

Abstract: An optical-optoelectronic coupling structure (70) comprising a flip-chip optoelectronic/ultrathin silicon-on-sapphire device (75) mounted on a V-groove, optical-fiber-bearing carrier substrate (71), including light-reflective structures (73, 77) for launching light into the optical fiber core (76) or transmitting light emitted by the optical fiber core to the optoelectronic device. The optical fiber (72) may be immobilized in the V-groove using a curable resin adhesive characterized by a refractive index substantially similar to the refractive index of the optical fiber.

Fine carbon fiber, method for producing the same and use thereof

Abstract: A vapor grown fine carbon fiber, each fiber filament of the carbon fiber comprising, in its interior, a hollow space extending along the fiber filament, and having a multi-layer structure, an outer diameter of 2 to 500 nm, and an aspect ratio of 1 to 100, wherein the fiber filament comprises a cut portion on its surface along the hollow space, a production method therefor, and electrically conductive material, a secondary battery and a gas occlusion material using the carbon fiber. The fine carbon fiber of the present invention is excellent in properties such as occlusion of gases such as hydrogen and methane, smoothness, electrical conductivity and thermal conductivity, and also excellent in dispersability, wettability and adhesion with a matrix such as resin.

Spectroscopic properties of Yb-doped silica glass

Abstract: We have carried out a systematic study of optical emission in Yb-doped fiber glass materials which can be used for fiber laser applications. The stimulated emission crosssections of these materials have been calculated. The wavelength dependence of emission of these materials has been studied. The peak emission cross section in Yb-doped silica glass is 2.6 pm2 and the peak wavelength is at 974 nm. The codopants do not significantly alter the emission cross section or the peak wavelength of this cross section.

Wavelength-selective optical fiber components using cladding-mode assisted coupling

Abstract: A wavelength-selective optical device for coupling of light at predetermined wavelength from one optical fiber waveguide (16) to another (18) using at least two gratings (22, 24) and cladding-mode assisted coupling is disclosed. The transfer of light is performed using intermediate coupling to one or more cladding mode of the waveguides (16, 18). In the case when the fibers have physically different claddings, an arrangement for transfer of light from one cladding to another is required. The disclosed coupler has no back-reflection, small insertion loss, and very high channel isolation. The device can be used in wavelength-division multiplexing networks.

Dispersion measurement of tapered air-silica microstructure fiber by white-light interferometry.

Abstract: Dispersion properties of novel, tapered, air-silica microstructure fibers are measured between 1.3 and 1.65 microm by white-light interferometry. Dispersion values (beta2) of -181 and -152 ps2/km were obtained for 2.2- and 3-microm core sizes, respectively, at lambda = 1.55 microm.

Hollow core photonic bandgap optical fiber

Abstract: A photonic crystal optical fiber made up of an array of conventional hollow core optical fibers is disclosed. The array of optical fibers omits at least one fiber to form a central hollow core. The fiber works on the principle of two-dimensional photonic crystals to confine the radiation in a guided wave within the central hollow core. The fiber has a true photonic bandgap in which radiation of a particular energy or wavelength is totally forbidden, thereby providing a very high reflection coefficient to radiation incident the walls of the central hollow core over a select range of angles. The central hollow core allows for radiation propagation with minimal absorption.

Optical coupling structure

Abstract: An object of this invention is to improve coupling efficiency of a silica optical waveguide having a high relative refractive index difference and a single mode optical fiber. A silica optical waveguide (l0) consists of a single mode optical waveguide, and its core (12) is originally a rectangle. A width of the core (12) of the silica optical waveguide (10) is tapered at a predetermined length part (16) connecting to an optical fiber (20). A thickness of the core (12) in the tapered part (16) is constant.

Measurement method for profiling the residual stress and the strain-optic coefficient of an optical fiber

Abstract: A method, believed novel, is demonstrated for determining the strain-optic coefficient profile as well as the residual-stress profile of an optical fiber by use of a modified polariscope combined with a fiber-elongation apparatus. Measurement results of the residual-stress and the strain-optic coefficient profiles for Ge-doped and Er-Ge-Al-doped optical fibers are demonstrated with this method.

Direct Photolithography on Optical Fiber End

Abstract: New photolithography techniques have been developed for fabricating an arbitrary structure on the optical fiber end One technique consists of preparing a uniform resist film on the optical fiber end The area of the fiber end is too small to apply the normal spin coating method The surface tension of the resist strongly disturbs the film uniformity The spray coating technique can be used to prepare a thin uniform resist film reducing the effect of the surface tension Another technique is for transferring the arbitrary pattern aligned to the fiber core The mask including the arbitrary pattern and the alignment guide hole is prepared using the self-aligning method These techniques are promising for fabricating the microlens which improves the coupling efficiency between the laser diode and the fiber The effect of the fabricated lens on the optical fiber end is confirmed

Single mode optical fiber, method of manufacturing the same, and apparatus for manufacturing the same

Abstract: In a single mode optical fiber formed of a silica-based glass and including a glass part having a central core and a cladding region, the density of non bridging oxygen hole center in the glass part is not higher than 1.0×1014 spins/g in terms of the spin density measured by an electron spin resonance method.

Splice joint and process for joining a microstructured optical fiber and a conventional optical fiber

Abstract: An optical splice joint and splicing process are provided for joining an end portion of a microstructured optical fiber (1) having a microstructure (5) formed from an array of holes (7), and a conventional optical fiber (3). The optical splice joint (27) is formed from a fused portion of opposing end portions (15, 17) of the microstructured optical fiber (1) and optical fiber (3), wherein the microstructured optical fiber (1) is surrounded by a jacket (9) that is at least 1.6 times thicker along its radius than the microstructure (5), and has a tensile strength of at least 30 Kpsi with an optical loss of less than 0.30 dB, and relatively little shrinkage (i.e., about 30%) of the holes (7) forming the microstructure (5). The splice joint (27) is formed by aligning end portions (15, 17) of the microstructured optical fiber (1) and the optical fiber (3), in a fusion splicer (18), and applying fusion heat to the fiber ends (25a, 25b) in a two step process with a low current arc (23) that is offset with respect to the end of the microstructured optical fiber (25a, 25b).

Ion adsorption in the porous sol–gel silica layer in the fibre optic pH sensor

Abstract: In the paper, the pH optical fibre sensor without any pH-sensitive dye is described. Porous silica film made by means of the sol–gel method was cladded onto optical fibre core and was exploited as the optical transducer. Acid–base properties of silica surface cause that the surface charge of silica changes with pH of solution. Negative surface charge (at pH higher than point of zero charge) of the silica surface is compensated by adsorption of cations. Saturation of the film with cations leads to an increase of the electron density of the film, hence, the refractive index of the film. Since the surface charge of silica depends on pH, the refractive index of the silica film varies also with pH. Thus, changes of the refractive index of the film, which plays role of the fibre cladding, modifies conditions of light propagation within the optical fibre. These phenomena are exploited in the U-shaped plastic clad silica fibre (core diameter 200 μm), in which 10 cm of original cladding was replaced with the sol–gel film. It is shown that the sol–gel film can be successfully used as the optical transducer with sensitivity up to 0.66 dB/pH for pH range 7–10.5. Moreover, the influence of the film preparation conditions on the sensor sensitivity and response time is also investigated.

Optical fiber for transmitting ultraviolet ray, optical fiber probe, and method of manufacturing the optical fiber probe

Abstract: It is an object of the present invention to provide an optical fiber for transmitting ultraviolet ray which has an improve transmittance and is prevented from deterioration by ultraviolet ray with which it is irradiated. It is another object of the present invention to provide an optical fiber probe which can propagate vacuum ultraviolet ray and deep ultraviolet ray at a high transmittance, is deteriorated only to a limited extent when irradiated with ultraviolet ray and can be etched to have a desired shape of the sharpened section at the fiber end. The present invention provides the optical fiber for transmitting ultraviolet ray which has a core 5 of silica glass containing a given content of fluorine and a clad 6 a of silica glass containing a given content of fluorine or boron, a clad 6 b of a resin which transmits ultraviolet ray or a clad 6 c having air holes H. The clad may be coated with a protective layer and further with a covered layer for protection. In particular, the core, clad and protective layer have a high transmittance for ultraviolet ray and resistance to ultraviolet ray with which they are irradiated, when treated with hydrogen. An optical fiber probe 1 has an optical fiber 2 provided with a sharpened section 3 at the end, which is sharpened with an etchant solution, the sharpened section 3 being coated with a light-shielding metallic film 4.

Termination of end-faces of air-clad and photonic-crystal fibers

Abstract: A method of preventing contamination of the air channels in the capillaries or pores of an air-clad or photonic-crystal fiber during polishing of the end-faces. A glass or silica fiber rod of diameter comparable to the fiber is fused to the end-face of the fiber, cut, and polished to form a thin protective plate having no appreciable affect on the optical properties of the fiber. Alternatively the air capillaries may be sealed by a UV-curable fluid or by melting the surrounding material. The end-face of the fiber thus presents a polished or cleaved surface for optical coupling to other fibers without causing damage or contamination to the air channels of the fiber. Furthermore, treating both end-faces of an air-clad or photonic-crystal fiber in manner provides a hermetic seal for the air-channels and protects the fiber against degradation caused by contamination such as humidity and dust which would otherwise enter the air channels over the course of time. Furthermore, there is a reduction in power density at the end-face of the fiber, which reduces the risk of damage. Anti-reflective coatings are consequently easier to apply and more stable. In addition to protecting the end-face of an air-clad or photonic-crystal fiber with a thin plate, it is also possible to utilize a graded-index (GRIN) element to perform both the protective function as well as an optical function.

Highly efficient acoustooptic tunable filter based on cladding etched single-mode fiber

Abstract: The efficiency enhancement of an acoustooptic tunable filter on cladding etched single-mode fiber (SMF) is investigated experimentally. When the fiber diameter is etched down to 30 /spl mu/m, the acoustooptic coupling efficiency from the LP/sub 01/ core mode to the LP/sub 11/ cladding mode was increased by an order of magnitude, and the RF power consumption was reduced by two orders of magnitude. A highly efficient 8-cm-long 25-/spl mu/m-thick AOTF on cladding etched SMF with an insertion loss of <0.2 dB, and RF power as low as 1.1 mW was demonstrated.

Capillary for optical fiber, ferrule for optical connector, and optical-fiber-fixed capillary

Abstract: The capillary for optical fiber has an inner hole allowing an optical fiber to be inserted and retained therein. Ra value of the surface roughness of the inner hole is 0.1 μm to 0.5 μm. The ferrule for optical connector is provided with a chamfered part on one end of the capillary for optical fiber for guiding it into a sleeve and a flared part on the other end of the capillary for optical fiber for guiding the optical fiber into the inner hole.

Cladding pumped large-mode-area Nd-doped holey fiber laser

Abstract: A large Nd-doped core placed in a microstructure cladding (holey fiber) was pumped with a low-brightness diode laser. The area ratio of the pump radiation on the fiber to the core was larger than 30. The fiber length was 38 cm. Butt coupled mirrors formed the laser cavity. The emitted radiation at λ = 1060 nm was single transverse mode, the output power amounted to about 10 mW.

1212 nm pumping of 2 μm Tm–Ho-codoped silica fiber laser

Abstract: A Tm–Ho-codoped silica fiber laser pumped by a third-stokes Raman Fiber Laser at 1212 nm is demonstrated. For the 30-cm-long Tm–Ho-codoped fiber, a 400 mW output power is obtained at a wavelength of 1790 nm due to the laser emission from the Tm3+ ions. For the 270-cm-long Tm–Ho-codoped fiber, a 450 mW output power is obtained at 1970 nm due to the laser emission from Ho3+ ions.