It is anticipated that more than 75 Mb/s per subscriber is required for the convergence service such as triple-play service (TPS) Among several types of high-speed access network technologies, wavelength-division-multiplexing passive optical network (WDM-PON) is the most favorable for the required bandwidth in the near future Furthermore, WDM technologies, such as athermal arrayed-waveguide grating (AWG) and low-cost light source, have matured enough to be applied in the access network In this paper, the authors propose and implement a WDM-PON system as a platform for TPS The system employs an amplified spontaneous emission (ASE)-injected Fabry-Pe/spl acute/rot laser diode scheme It has 32 channels of 125 Mb/s and adopts Ethernet as Layer 2 Multicast and virtual local area network features are used for the integration of services such as Internet protocol high-definition broadcast, voice-over Internet protocol, video on demand, and video telephone The services were demonstrated using the WDM-PON system

Fiber-to-the-home services based on wavelength-division-multiplexing passive optical network

A rod-in-tube method for producing a glass preform for use in the fabrication of an optical fiber, which comprises steps of inserting a glass rod (13) as a core material in a glass tube (12) as a cladding material, fusing and closing one end of the cladding material, filling a gap between the core and cladding materials with an atmosphere containing at least one gaseous halogen-containing compound and then heating the core and cladding materials at a temperature not lower than 1,900°C to collapse the gap between them and to fuse them together, from which glass preform, an optical fiber with low attenuation of light transmission is fabricated.

Method for producing glass preform for optical fiber

A thermal recording material comprising a support and, sequentially superimposed thereon, an undercoating layer, which contains a pigment and a binder as main components, and a thermal recording layer, which contains an achromatic or hypochromic basic colorless dye and a developer capable of reacting with the basic colorless dye to thereby realize color formation as main components, wherein the undercoating layer comprises a carboxymethylcellulose exhibiting an etherification degree of 0.55 to 0.75. Causing the undercoating layer to further contain hydroxymethylcellulose is preferred from the viewpoint of high effectiveness.

Thermal recording material

Erbium-doped fiber has become the central component of nearly all optical amplifiers. Applications reported include repeaters, power amplifiers, preamplifiers, and distributed amplifiers. To date, nearly all the fiber used in these devices has been silica based and fabricated by variations on the major telecommunications fiber technology. Disadvantages of the silica-based host glass, such as low solubility of the rare-earth ions and narrowband fluorescence, have been carefully addressed and solutions have been found to overcome these potential drawbacks. Details of the current status of fabrication methods, matching particular fibers for specific applications, together with optimizing the fiber for high efficiency, are presented. >

A review of the fabrication and properties of erbium-doped fibers for optical amplifiers

Silica-based planar lightwave circuits (PLC) provide various important devices for both optical wavelength-division-multiplexing networks and optical access network. This paper is an overview of recent progress in PLC technology including optical power splitters, arrayed-waveguide gratings, thermooptic switches, and hybrid integrated PLC's.

Silica-based planar lightwave circuits

A temperature dependent channel wavelength shift in a silica-based arrayed-waveguide grating multiplexer is successfully suppressed from 0.95 to 0.05 nm in the 0-85/spl deg/C temperature range, which means that it can be used in practical WDM systems without the need for temperature control.

Athermal silica-based arrayed-waveguide grating multiplexer

An optical waveguide circuit includes a plurality of waveguides with different lengths. Grooves (12) are formed in the waveguide by removing the upper cladding and the core of the waveguide (4) or by removing the upper cladding, the core and the lower cladding of the waveguide (4), and filled with a material (10) which have a refractive index temperature coefficient whose sign is different from the temperature coefficient of the effective refractive index of the waveguide. The difference between the lengths of the removed parts of the adjacent waveguides is proportional to the difference between the lengths of the remaining parts of the adjacent waveguides.

Optical waveguide circuit, its manufacturing method and optical waveguide module having the optical waveguide circuit

An extremely low OH v.a.d. fibre has been fabricated. The attained minimum OH concentration is estimated to be 0.8 ppb and optical loss below 1 dB/km is realised in the extended wavelength range from 1.1 to 1.7 μm.

Fabrication of completely OH-free v.a.d. fibre

Residual stress and its influence on optical characteristics have been investigated for pure‐silica (SiO2)‐core/fluorine‐doped‐silica(F‐SiO2)‐clad single‐mode fibers. Theoretical analysis has shown the following: (1) Very high residual stress concentrated at the small‐diameter core region is induced by drawing tension because of the viscosity difference between core and cladding. (2) The refractive index in the core is reduced greatly by the residual stress via the photoeleastic effects. (3) The decrease in the refractive index results in the shift of the cutoff wavelength to shorter wavelengths. These characteristic features have been ascertained experimentally in SiO2‐core/F‐SiO2‐clad single‐mode fibers drawn at various conditions, indicating the optimum drawing condition and structure for the single‐mode fibers.

Drawing-induced residual stress effects on optical characteristics in pure-silica-core single-mode fibers

Manufacturing method of doped silica glass suitable for optical fiber wherein quartz powder or SiO2 glass fine particles are exposed to a gas for producing the doped silica glass containing SiCl4, a gaseous additive and water vapor (H2 O) to add the dopant to the glass body, and then the resulting glass body is fused at a high temperature, thereby producing a transparent doped silica glass in which the production of the glass particles, the addition of the dopant, and the vitrification of the glass body are carried out by separate steps under respective suitable conditions. The manufacturing speed is remarkably increased because of the separate steps. The content of the dopant is not limited, but can be adjusted with any desired amount by changing the reaction time of dissolution. Dopant components like PbO2, SnO2, ZnO which were typically not added to the glass body can now be added thereto. Also, a method of manufacturing an optical fiber preform is disclosed wherein the doped silica glass is deposited and fused on a starting material which is inclined by an angle within a range of 5°-90° with respect to a blow-off direction of the flow of the doped silica glass to form a transparent doped silica glass body having a uniform outer diameter and a uniform boundary surface at a high synthesizing speed. This latter method aids mass production of optical fibers at low cost.

Hanawa Fumiaki

Papers

Athermal silica-based arrayed-waveguide grating multiplexer

Optical waveguide circuit, its manufacturing method and optical waveguide module having the optical waveguide circuit

Fabrication of completely OH-free v.a.d. fibre

Drawing-induced residual stress effects on optical characteristics in pure-silica-core single-mode fibers

Fabrication methods of doped silica glass and optical fiber preform by using the doped silica glass