Fujikura Ltd.

  1. Home
  2. R&D
  3. Fujikura Technical Review
  4. No.37 January, 2008
Fujikura Technical Review

No.37 January, 2008

In the realm of information and telecommunication, Fiber To The Home (FTTH) and Next Generation Network (NGN) are the latest trends that have captured attention of the people worldwide. FTTH offers high-speed data transmission through optical fiber to subscribers, thus connecting every home. There are currently eight million subscribers in Japan who use this technology, and NTT has announced various plans to increase the number of subscribers to 20 million by 2010. Also, it has been predicted that there would be 150 million subscribers globally by 2010.
In an FTTH network, the mechanical splice is the key "Tsunagu" technology for connecting subscribers by the use of optical fibers. It mechanically connects two optical fibers on a v-groove. Fujikura has recently released a new mechanical splice (FMSEZ-025/09) that is compatible with both φ900 µm and φ250 µm single-core optical fibers. Besides being able to connect two fibers of the same diameter, this new mechanical splice is also able to connect a φ900 µm fiber to a φ250 µm fiber.
To improve the ease and reliability of connection for all users, the assembly tool has also gone through a design change (photograph). This new tool is light in weight and ergonomic, so it can be used everywhere, even near the closures and cabinets.
The most important step in splicing is the verification of fiber connection. This is achieved by visual inspection of the fiber bends, which is a more reliable method than the present one. The fiber holder approach is retained to provide an easy assembly.

Tsunagu: This Japanese word means "tying," "connecting," "communicating," and so on. This word represents the management policy of Fujikura Ltd.


Temperature Compensated Optical Water Level Sensor Utilizing Three-fiber Array

An inexpensive and high-accuracy optical sensing method utilizing an angled three-fiber array is proposed and demonstrated. By using a combination of a temperature and pressure sensor, we achieved an accuracy of +/-0.3%F.S. in our temperature compensated water level sensor.

Small-Silica-Core Polymer-Clad Fiber for Optical Interconnection

A polymer-clad silica-core fiber (PCF) with a small core diameter that is suitable for an optical interconnection is studied and experimentally manufactured. Error-free transmission over 2.5 Gbps in a 20-m link can be supported by manufactured fibers with VCSEL excitation. Large tolerance for a fiber connection and small bending loss for a small bending radius are experimentally confirmed.

Radiation-Resistant Single-Mode Optical Fibers

Loss of silica-based optical fibers increases when they are exposed to radiation. We have developed a fluorine-doped core single-mode optical fiber, which complies with ITU-T G.652.B and has excellent radiation-resistant characteristics compared with pure silica core single-mode fiber. Although the increase in radiation-induced loss of the conventional pure silica core single-mode fibers with the condition 1 × 106 R/h and 60 min is approximately 25 dB/km at 1310 nm wavelength, the loss of the fluorine-doped core single-mode fibers with the same condition is approximately 5 dB/km at 1310 nm wavelength. In addition to the excellent radiation-resistant characteristics, we have confirmed that the fiber has an excellent loss recovery characteristic after irradiation.

Field-Installable Fusion Splice Connector

Installing optical connectors in a Fiber-To-The-Home (FTTH) network usually involves field-installable connectors employing mechanical splices. However, some FTTH systems require low-reflectance connectors, demanding ease of installation and robustness of the Kevlar-reinforced fiber cord termination. To meet this requirement, Fujikura has developed a field-installable fusion splice connector that is easy to install and is highly reliable.

Compact Optical Splitter Module for FTTH Outside Plant

Passive Optical Network (PON) system has expanded extensively as an optical network in the construction of Fiber To The Home (FTTH) economically. To allow multiple users to share an optical fiber in a PON, the optical splitter that branches an optical signal is indispensable. Recently, plug-and-play structures that make use of modules and connectors are desired to simplify the installation construction of optical splitters. Moreover, because the splitter module is installed in the outside plant, high reliability that can endure harsh environmental conditions is a critical requirement. In addition, compactness and cost savings are also important considerations. Therefore, we have developed it by economically using a superior flame-retardant plastic resin for the module case. We have confirmed that the optical splitter modules have excellent optical characteristics and sufficient reliability.

Low-friction and Abrasion-resistant Optical Drop Cables/Super Low
Friction Optical Indoor Cables

The number of aerial optical cable installations has increased rapidly because of the growth of the fiber-to-the-home (FTTH) market. Therefore, a lot of optical drop cables are installed in a supporting wire, generally, by using a spiral hanger. During installation, because the optical drop cables are found rubbing each other in the same spiral hanger, a material with both low-friction and abrasion-resistance performance is required for the sheath. For this reason, we recently developed the low-friction and abrasion-resistant optical drop cables. Moreover, to make the passing through of the conduit line easier, we also developed super low friction optical indoor cables.

Passive-Device-Embedded Flexible Printed Circuit Boards

Capacitors, inductors, and resistors were formed in multilayered flexible printed circuit boards (FPCs) utilizing integrated passive device component technology. Capacitors in the range of 36.5-1310 pF were fabricated using an organic dielectric material. Resistors with 0.03-600 kΩ resistance were also formed by etching a metallic thin film of various dimensions. Inductors, designed by the high-frequency structure simulator (HFSS), were formed by the through hole printed circuit technology. It was shown that the electrical properties of these embedded components could be controlled by their circuit design.

New Via Interconnection Technology - CBIC

Through Hole (TH) or Laser Via Hole (LVH) are used commonly as the interconnection technology of multi layer printed circuits. In addition to the conventional technologies, we started the development of CBIC, which is a new interconnection technology with copper balls. We found copper balls and copper foils could be bonded strongly when they were pressed in high temperature. As compared to conventional technologies, reduction in manufacturing defects and improvement in connection reliability can be expected.

Test of Cryocooled Oxide Superconducting Magnet

Since yttrium series coated conductors show a high conductivity, their applications to various electric power devices such as transformers, motors, and current-limiting devices are now being studied. We are developing yttrium series coated conductors using the Ion Beam-Assisted Deposition (IBAD) method and the Pulsed Laser Deposition (PLD) method. This paper reports the present status of development of the yttrium series coated conductors and the results of the current tests for the conduction cooling magnet using a coated conductor that we have developed.

Low-loss Coaxial Cable with Highly Foamed Insulator

As the transmission speed and capacity of communication have increased in recent years, the operating frequency has shifted to a higher frequency region. So coaxial cables having low attenuation in high operating frequency are required. For the insulation material of the high-frequency coaxial cable, polyethylene is used because of its low dielectric constant (εr) and dielectric loss tangent (tan δ), and easy foam extrusion. To reduce attenuation, we developed a new material that was excellent in both melting and dielectric characteristics. Further, we developed a highly foamed coaxial cable insulator having a foaming degree of 85 percent.

Two-chip Si Pressure Sensor

We have developed a "Two-chip Si pressure sensor" that consists of two chips. One is a Si pressure sensor chip and the other is an ASIC for signal conditioning of a sensor chip. Comparing with monolithically integrated pressure sensors, this configuration enables higher accuracy, wider pressure range and operating temperature, more flexible operation to changes of supply voltages and output ranges, which are suitable to fulfill diversifying demands from customers. Wide operational temperature ranges from -40 - 125 °C and a total high accuracy of ±1.5% FS (0 - 85 °C) is obtained.