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  4. No.41 January,2012
Fujikura Technical Review

No.41 January,2012



Optical Characteristics of a Reduced Bending-Loss Fiber with a Bending Radius of 5 mm

With the worldwide popularization of fiber-to-the-home (FTTH) service, extremely lowbending- loss optical fibers with a small bending radius are requested from the viewpoint of easy fiber installation and space-saving storage for excess fibers. To meet the demand, we have developed a reduced bending-loss fiber with a bending radius of 5 mm, which is compliant with both ITU-T G.657.B3 and G.652.D recommendations. The newly developed optical fiber shows a satisfactory connectivity to conventional single-mode fibers, and is suitable in use for FTTH system.

1180-nm Linearly Polarized Fiber Laser Using Yb-doped Polarization-Maintaining Solid Photonic Bandgap Fiber

We have developed an 1180-nm linearly polarized Yb-doped fiber laser for a yellow-orange frequency-doubling laser. An Yb-doped polarization-maintaining solid photonic bandgap fiber (Yb-PM-SPBGF) is employed to suppress parasitic lasing, which limits the output power of 1180-nm linearly polarized fiber lasers. An output power of 10.8 W is achieved at a pump power of 23.4 W. Slope efficiency and conversion efficiency are 56% and 50%, respectively. Narrow spectral width, high polarization extinction ratio, and high beam quality, which are required for efficient frequency doubling, are also achieved. The 1180-nm linearly polarized fiber laser developed by us can realize a compact and powerful yellow-orange laser.

Fusion Splicer for Specialty Optical Fiber with Advanced Functions

The application of optical fiber technology has advanced beyond the field of telecommunications and into a variety of other fields. Completely new fiber types have been developed to enable many other applications, and this trend is increasing. Last year, we introduced a fusion splicer that was developed to achieve high-quality splicing performance with these specialty optical fiber applications, model FSM-100M/FSM-100P. Now we have developed a new fusion splicer with more advanced features and functions in order to offer further capabilities such as splicing fibers with diameters as large as 1200 μm, and to observe the fiber end surface for aligning specialty fibers such as multi-core, non-circular, and polarization-maintaining optical fibers.

Fault Location System for Power Transmission Lines Applying Optical Fiber Current Sensors

Surge-receiving-type fault location systems have recently been used for fast recovery of underground transmission lines from ground faults. Electromagnetic induction type sensors have mainly been used for detection of surge currents. However, they are susceptible to electromagnetic noise, which causes unstable system operation. To solve this problem, we developed a new system using optical fiber current sensors.

The Development of High-Heat-Resistance Insulating Material for Automobiles

We report flexible silicone rubber insulating cable for hybrid electric vehicle (HEV) and electric vehicle (EV). Insulating cables for HEV/EV are required to have high voltage resistance and heat resistance properties, Fujikura has developed insulating cables using silicone rubber that meet these conditions. On the other hand, silicone rubber has weak point of being swellheaded by absorption of nonpolar oil, such as gasoline and light fuel oil. We realize the most important thing is the balance of chemical and physical crosslinks. The result of experimentation is that crosslink-controlled silicone rubber showed improved mechanical characteristics in chemical-resistance test.

AlN Bulk Single Crystals Growth

Single crystalline aluminum nitride (AlN) is an indispensable material as a substrate for improving the quality of III-nitride semiconductors based on AlN expected to be applied for power electronics devices and deep UV LEDs/LDs. In this study, we report growth of highquality AlN bulk single crystals by sublimation method (modified Lely method) on SiC seed crystal. Moreover, we succeed in the high-speed growth of AlN bulk single crystals on AlN seed crystal. 1. Introduction

Single Crystals for Optical Isolator

Currently, Tb3Ga5O12(TGG)single crystal is used as Faraday rotator in the laser machinery the wavelength of which is <1100 nm. However, TGG has problems of not enough Faraday rotation angle, difficult crystal growth, very high price, and so on. In order to overcome these problems, we focused on Tb3(Sc,Lu)2Al3O12(TSLAG) single crystal and grew and characterized TSLAG crystals. In this paper, we report that TSLAG can be grown easily and has higher transparency, larger Faraday rotation angle, and extinction ratio, which are very important properties for Faraday rotator.

Outdoor Performances of Dye-Sensitized Solar Cell

Dye-sensitized solar cells (DSCs) are expected to be next-generation solar cells because of their lower cost and more environmentally friendly features compared with conventional solar cells. With the aim of commercializing our highly durable DSC modules, we tested their durability over long time and measured electric output during outdoor operation to evaluate the performance of actual solar energy conversion. The energy conversion efficiency of dyesensitized solar cells measured under outdoor conditions was larger than that measured under JIS-specified conditions, and the annual energy production of the dye-sensitized solar cells was larger than that of a Si solar cell of the same rated output .

Low-loss Millimeter-wave Passive Devices on Si Substrate

Low-loss wiring board operating at millimeter-wave band is becoming more and more important these days because high-speed and large-data communications exceeding a few Gbps are being made available by utilizing CMOS technology operating at millimeter-wave frequency band. We designed and fabricated millimeter-wave transmission line and bandpass filter as passive devices to be integrated on the millimeter-wave wiring board by using a copper wiring technology on silicon, and achieved low attenuation constant α of 0.2 dB/mm in the transmission line and an insertion loss of 4.67 dB with 1 dB FBW of 7.0% in the band-pass filter.