Design of ferrule hole diameters in a ferrule-type single mode fiber connector has been investigated to achieve a low-loss multi-fiber connection. Based on the theory of the connection loss statistics, connection losses for various designs of ferrule hole diameters are evaluated and discussed.

In order to develop a light and small sized fusion splice machine operating from a small battery, a new high frequency discharge method with high voltage trigger has been developed. The method uses a high voltage trigger at the beginning of discharge to reduce power consumption. It was found experimentally that the voltage of an A-C discharge depends vastly on the applied voltage waveform. To use a high voltage trigger method effectively, pertinent applied voltage conditions were found considering the ion movement. By adopting pertinent conditions, the power consumption for discharge reduces to 1/5 of that for the conventional discharge method. The new method is adopted for developing a fusion splice in optical fibers. The developed machine is 2.5 kg in weight including battery, and consumes 25 watts electric power. The average splice loss and splice tension strength are 0.03 dB and 480 g, respectively.

The construction of an optical subscriber loop and its operation system will be one of the most important infrastructures for the information society of the future. This paper presents a discussion of current and future service trends, the evolution of fiber-optic systems in the loop, and subscriber loop operation systems. Several operation technologies are also discussed which will enable the operation systems described in this paper to be constructed. Of these, the key technologies are an operation system architecture with flexibility, software technologies based on object-oriented design and programming, and automatic operation modules.

A small plastic molded 50-fiber connector has been developed for high-count optical subscriber cables. The connetor ferrule has a two-dimensional fiber arrangement constructed by five layered 10-fiber ribbons. The ferrules are precisely aligned by alignment pins and a guide sleeve. The fabricated 50-fiber connector, which has a small sectional area of 4 mm6 mm, exhibits an average loss of 0.23 dB for graded-index optical fibers. Connection loss chang is small after over 1000 times reconnection.

This letter proposes a novel type of 12 optical switch with a plastic-molded ferrule wherein an alignment mechanism is formed. Discussing the errors in ferrule fabrication, the insertion loss of the switch has been evaluated. The constructed switch for multimode fibers has shown an insertion loss of 0.7 dB and a switching time of 4 msec.

This letter describes structural design of a ribbon-to-single-fiber fanout connector. Considering bending strain and bending loss applied to the fibers for fanout, the relationship between the number fibers in the ribbon and the minimum length for fanout has been clarified.

This letter describes design and performance of small-size push-on type connectors. Considering bending and tensile stress applied to the push-on type coupling, the minimum dimensions of the coupling have been clarified. The constructed connectors for multimode fibers showed average insertion losses of 0.1-0.2 dB.

Centering effect in single mode multi-fiber connectors in investigated precisely by measuring connector loss with various clearances. By comparing the measured loss with the theoretical estimate, the range of clearance over which the centering effect holds is determined.

We propose a distributed operation system platform for optical cable networks. This distributed platform is an extension of the previously proposed platform for a flexible cable network operation. The concept of the unit platform has been proposed for the distributed operation system platform. By using this concept, we discuss the system upgrade including the connection to other operation systems. We use an object-oriented software technology for designing the distributed operation system platform. The prototype system has been constructed using C++ programing language and the evaluated results are shown.

We propose an integrated smart cable operation system and its architecture for the future cable network. In the proposed architecture, an application programs and various modules are loosely coupled using a cable operation system platform. We anticipate the task flows for the future optical cable network operation in order to realize the proposed system and architecture. Each task flow is broken down into "atomic tasks." The task flow can be changed easily by combining these atomic tasks. We use an object-oriented design for designing the cable operation system platform. As a first step towards the construction of the proposed system a pre-prototype system was constructed and the results are shown.

A computer aided local estimation of fusion splice loss for graded-index optical fibers is proposed. Spliced fiber outer diameter deformation is extracted by image processing technique. The relation between deformation at the splice portion and splice loss is obtained experimentally. It is possible to eliminate large loss splices automatically using the splice portion appearance.

This letter describes design and performance of a multicore fiber connector with a plastic-molded ferrule. Discussing ferrule fabrication errors, the connector loss and crosstalk were evaluated. The constructed connector for joining and fanouting multimode two-core fibers showed an insertion loss of 0.4 dB and a crosstalk of less than 35 dB.

Single-mode 1 N switch for 10-fiber ribbon has been developed. The switch has a movable 10-fiber connector plug and linear arrangement of 10-fiber plugs to be mated. The plugs are precisely aligned by inserting alignment pins. The tested 1 50 switch exhibits an average insertion loss of 0.5 dB for single-mode potical fibers with 10µm core. The minimum and the maximum switching times are 17 msec for port 1 to 2 and 80 msec for port 1 to 50, respectively. Insertion loss change after over 1000 times switching is less than 0.1 dB.

The relation between connection loss and fiber diameter is investigated for a ferrule-type single mode multi-fiber connector. The theory for the connector loss statistics is derived taking the centering effect in a ferrule-type connector into account. Five-fiber connectors for single mode fibers are manufactured. Their connection losses are measured and compared to the theory.