Shuichi Yanagi

Fiber fuse generation in single-mode fiber-optic connectors

The evolution of the fiber fuse phenomenon in a single-mode fiber-optic connector was studied theoretically. A narrow air gap of the order of 1 /spl mu/m was assumed to be formed between the fiber end-faces in the connector as a result of the adhesion of dust to both the ferrule and the fiber end-faces. It was assumed that there was a thin water layer in the gap because condensable water molecules in the air could easily be trapped by the SiOH groups on the silica-glass surface. The water layer exhibited a large absorption coefficient of about 850 cm/sup -1/ at 1.48 /spl mu/m. The temperature distributions near the air gap were numerically calculated by using the explicit finite-difference method. When a high-power laser operating at 1.48 /spl mu/m was input into the connector, the temperature along the fiber-core center increased abruptly at the thin water layer. The air gap was heated above 4/spl times/10/sup 5/ K when the optical power was 2 W and the gap was 1 /spl mu/m. The heat in the air gap gradually diffused into the neighboring optical fiber over time. The temperature of the heated fiber reached over 1/spl times/10/sup 4/ K, which is high enough to initiate the fiber fuse phenomenon.

Fiber fuse terminator

We developed a fiber fuse terminator to ensure the safe operation of high power optical network systems. The performance of this fiber fuse terminator was satisfactory as regards an optical input of 2 W.

Physical-contact conditions for multicore fiber optical connectors

We clarify the physical-contact conditions for multicore fiber connectors with good optical characteristics, and demonstrate physical-contact multicore fiber connectors with a sufficiently high return loss of more than 40 dB for all cores.

Optical characteristics of injection molded plastic ferrules for single-mode optical fiber applications

We injection molded a plastic ferrule for a single-mode optical fiber connector. We used liquid crystalline polymer (LCP) as the molding material because of its fine mold replication ability and introduced an eccentricity control mechanism into the ferrule mold. As a result, we succeeded in molding plastic ferrules whose eccentricity was less than 1 /spl mu/m by optimizing the eccentricity control conditions. The connection loss of these low eccentricity plastic ferrules was around 0.2 dB and they exhibited an excellent reflection characteristic of 52.5 dB. These initial results were maintained during mating tests and temperature and humidity cycling tests.

Optical characteristics and reliability of plastic split alignment sleeves for single-mode optical fiber connectors

Split alignment sleeves for single-mode (SM) optical fiber connection are fabricated with a precise injection-molding technique using a thermosetting epoxy resin. The fabricated plastic sleeves exhibit dimensional accuracy of 50 dB. The plastic sleeves exhibit good resistance in 500-cycle mating tests using zirconia and/or glass ceramic ferrules, and in vibration and impact tests as well. The initial optical characteristics are maintained in both short-term and long-term environmental durability tests.

Compact multi-fiber receptacle interface for on-board optical interconnection

We have developed a new type of receptacle interface that enables us to achieve dense multi-fiber connection between a planar lightwave circuit based optical device and single-mode fibers on a printed circuit board. To obtain both a small size and good optical performance with this interface we devised a small fiber guide for aligning the fibers with waveguides, and also developed a refractive-index-matching gel that maintains stable optical performance. We fabricated sufficiently small (5 mm long) 32-fiber interfaces, and successfully obtained low connection and high return losses with average values of 0.17 and 60 dB, respectively. We also demonstrated that the interface can provide sufficient environmental durability. Our new interface eliminates the need for pigtail fibers on the board, and this will lead to the development of dense and low-cost optical interconnection on a board for advanced optical network systems.

10-year reliability test results for SC connector installed on outside plant

Since 1997 we have tested the reliability of SC connectors installed outdoors in hot and humid environments. SC connectors with optimized ferrule end dimensions have maintained good optical performance for 20 years.

Development of a Rapid Polishing Machine for On-Site Optical Connector Assemble

Field assembly of optical connectors is demanded because of the wide use of optical fiber in telecommunications systems. We propose a new assembling techniques that enable us to assemble connectors anywhere quickly and cost effectively. The key points are an adhesive technique and a polishing technique. In this report, we focus mainly on our a new polishing machine, which is suitable for optical connector ends machining on-site. The machine which is small and light weight can finish optical connector ends easily in a short time with enough low cost.

Plastic split alignment sleeves for single-mode fiber connection of MU- and SC-type ferrules

Split alignment sleeves for the single-mode optical-fiber connection of MU and SC-type ferrules were successfully fabricated for the first time with a precise injection-molding technique using a thermosetting epoxy resin. The optimum inner radii of the plastic sleeves were determined with a view to realizing both suitable gauge retention forces for the ferrules and a small fiber offset of 1 /spl mu/m between them. The adapters incorporating the plastic sleeves showed excellent performance with an average connection loss of 0.09 dB and a return loss of >50 dB.

Nondestructive Three-Dimensional Observation of the Influence of Zirconium Inclusions in Laser-Irradiated Fusion-Spliced Optical Fiber on Core Structure Changes Using Synchrotron Radiation X-ray Micro-Computed Tomography

In this paper, we describe a nondestructive method of observing changes in the microstructure of optical fibers subjected to CO2 laser irradiation for optical fiber splicing using synchrotron radiation micro-computed tomography (CT). In particular, we evaluated a method of enhancing the contrast between a GeO2-doped optical fiber core and a silica cladding by performing CT observations of the X-ray energy around the Ge-K absorption edge. Specifically, procedures for extracting a GeO2-doped core from a three-dimensional image of optical fibers by the cluster labeling method are proposed and evaluated. The approach enabled us to observe how inclusions at the optical fiber splicing interface influence the optical fiber core structure. We also expect this observation method to be used for improving such aspects of laser processing performance as insertion loss and mechanical strength for recently developed optical fibers.