Fujikura Ltd.

Fujikura Technical Review

No.43 March,2014



Silicon Quadrature Phase-Shift-Keying Modulator for 40- and 100-Gb/s Transmission

Silicon modulators are promising devices for future optical networks to realize large capacity transmission with a low cost and a small footprint. In this paper, a silicon modulator for quadrature phase-shift-keying format is designed, fabricated and characterized. The fabricated modulator chip has short length of 3.5 mm, which is approximately one tenth of a widely used lithium niobate modulator chip. Quadrature phase-shift-keying modulation as high as 64 Gb/s has been achieved with a low bit-error-rate. The silicon modulator will be applied to 40- and 100-Gb/s transmissions in the near future.

Ultra-High-Density Optical Fiber Cable

In order to construct optical fiber networks economically and efficiently, we have successfully developed new Ultra-High-Density optical fiber cables which are applied for underground and aerial networks. These cables contain our novel optical fiber ribbons "Spider Web Ribbon" which consists of a group of 250 micron coated fibers bonded intermittently. The novel fiber ribbons are easily bundled or bunched without loss increase that helps to reduce the dead-space of conventional cables. By optimizing several structural parameters, the new cable dimension has been reduced by 29 % in diameter and 52 % in weight compared with the conventional cable. We have achieved the highest level of the fiber packing density in the world.

Digital Output Ultra-Small Atmospheric Pressure Sensor

Recently, portable electronic equipment driven by batteries has been developed one after another in various fields such as mobile communication, healthcare, and so on. Accordingly, demands for value-added products integrated with various sensors are growing in these fields. A pressure sensor for measuring atmospheric pressure is one of the devices that attract attention. In addition, the miniaturization and the low power consumption of the sensor are indispensable to the portable electronics. To meet the demand, we have developed a new digital output ultra-small atmospheric pressure sensor that works with low power consumption. In this report, the features of the developed sensor are described.

New Compact Fusion Splicer for FTTH

Fusion splicing is a commonly used method to join two optical fibers together in the installation of FTTH (Fiber To the Home) networks. The FTTH installation includes a variety of workplaces such as an aerial cable, a narrow space, or a place without commercial power supply. Most installers implement the installation moving place to place. Therefore, the portability of a fusion splicer is a desired feature. In addition, customers increasingly put importance on the maximum number of fusion splicing and reinforcing with a fully charged battery because commercial power supply is not available in many installation sites. To respond to such needs, Fujikura has developed a smaller, lighter fusion splicer that allows an increased numbers of fusion splicing or enforcing by heat.

This paper reports a novel compact fusion splicer equipped with a high battery capacity.

Super-Thin Leaky Coaxial Cable ZLCX-2.5D

Recently, demand for leaky coaxial cables (abbreviated as LCX hereinafter) as a thin and lightweight antenna for small area networks in meeting rooms or instruments is increasing. We have developed ZLCX-2.5D that is the thinnest and the lightest LCX, whose diameter is 4 mm and weight is 20 g/m. The measured coupling loss and transmission loss at 2.4 GHz are 57 dB and 1.3 dB/m, respectively. As this new LCX has superior performance, it is applicable to an antenna for 2.4GHz wireless LAN system in a small space.

Super fine membrane circuit board

We have developed a gravure-offset printing technology to achieve a finer trace width than that of a screen printed one. We have successfully produced a super fine membrane circuit board of L/S=30 μm. This product is promising for uses in a capacitance touch panel with peripheral routing traces or transparent electrodes with fine silver mesh traces. In this paper, we report the printing technology and the properties of the membrane circuit board.

The World's Largest 5 T Yttrium-based High Temperature Superconducting Magnet with a 20-cm-diameter Room Temperature Bore

Y-based superconducting wires are expected to show high performance in superconducting applications because of their high mechanical strength and high current density in magnetic fields. We have succeeded in developing the world's largest Yttrium-based high-temperature superconducting (HTS) magnet, which stores energy of 426 kJ. The magnet is composed of 24 pancake coils with an inner diameter of 260 mm. The total length of the Y-based superconducting wires is approximately 7.2 km. These superconducting wires were fabricated using ion-beam-assisted deposition (IBAD) and pulsed laser deposition (PLD) methods. In 2012, we excited the magnet up to 5 T around 25 K, successfully. We have demonstrated that the magnet can be excited up to 5 T in 720 min 9 months after the fabrication of the magnet. We have also confirmed that the developed magnet can be used as a background magnet for measuring critical current in magnetic fields of the Y-based superconducting magnet.

Non-halogen and non-phosphorous flame-retardant polymer

Flame-retardant polymer harmless to the environment and the human body is receiving attention with growing environmental awareness. Recently, we have developed flame-retardant polymer which offers high flame retardancy and conforms to the environment without using halogen compounds or phosphorous compounds. The developed polymer has high performance to pass the single vertical wire flame test (JIS C3665) and the vertical tray flame test (JIS C3521), and the characteristics suitable for use in insulation and jacketing of wires and cables.

Hetero-epitaxial Growth Mechanisms of AlN Single Crystals in Sublimation Growth

An aluminum nitride (AlN) single crystal is a promising material as a substrate for AlN-based semiconductors used in low-loss electronic devices and DUV emitting devices. We have developed a growth technology of AlN single crystals by a sublimation method which uses silicon carbide (SiC) as a seed. We observed the surface morphology focusing on the growth of the crystal at the initial stage. We have derived a novel model that explains the formation process of pyramids and the nucleation of AlN from the observation results. In addition, the apparent rotation of the facets of AlN islands with respect to the facets of pyramids is 30 degrees. However, it has been found that AlN and SiC had the same crystal orientation by crystallographic evaluations.