The demand of optical fibers has been expanding as the capacity of communication network has been increasing. In Japan, there is a strong demand for small-diameter and high-density optical cables to increase the number of fibers in a conduit in order to achieve both installation cost reduction and larger capacity. This paper introduces the high density 3000-fiber cable utilized for underground network, which has been achieved by using 200 µm fibers and furthermore by applying Spider Web Ribbon™ / Wrapping Tube Cable™ ( SWR™ / WTC™ ).

An innovative self-supporting high-density cable with high strength sheath for aerial application was developed. By using Spider Web Ribbon^® / Wrapping Tube Cable^® (SWR™ / WTC™) technology, extremely reduced outer diameter and weight were achieved compared to existing cable. In addition, the developed cable has not only functions equivalent to existing cable but also excellent mid-span access workability.

The rapid growth of the optical network traffic has dramatically increased and the demands for high bandwidth and multi-fiber optical connection needs are increasing. We have developed an Ultra Low Loss (ULL) MPO connector equipped with an MT ferrule with a low fiber core eccentricity, a lower loss of connection than conventional MPO connectors, a good track record as multi-fiber optical connectors, excellent insertion loss and mating repeatability. The 12 fiber single mode 12 ULL MPO connector and the 24 fiber single-mode 24 ULL MPO connector have been confirmed to have a maximum insertion loss of less than 0.20 dB after 50 repetitions of insertion and removal, resulting in a stable ultra low loss connection. Also, this ULL MPO can be manufactured at almost the same cost as the conventional MPO.

The telecommunications optical fiber infrastructure market is still growing due to increasing bandwidth demands. One of the most reliable methods for terminating fiber is fusion splicing. In particular, core alignment fusion splicers produce consistent low-loss splices. However, fusion splicing is often seen as a complicated process which requires skilled operators. As a result, the industry demands an easy-to-use splicer that unskilled users can use to successfully complete low-loss splices. Because of the increasing number of fibers to be spliced, the splicer should feature very fast and efficient operation. To meet these expectations, we have developed a new core alignment fusion splicer with quick and simplified operation that is not possible with other splicers.

Silicon Photonics-based devices are attractive owing to their advantages such as compactness, high functionality, and low-cost fabrication. One of the challenges is the optical coupling loss due to the spot size mismatch between the silicon waveguides and standard optical fibers. We have developed low-loss coupling fibers between them. This study reports the improvements in their splice losses with standard optical fibers by optimizing the fiber structure. Moreover, the fibers developed in this study show reflow-soldering resistance upon application of a high-temperature resistant coating.

As light sources of fiber laser system, which is spreading rapidly in the material processing field, high power and high efficiency 9xx- nm LDs are strongly demanded. In order to improve PCE by reduction of electrical resistance, vertical designs of LD are optimized. As a result, the newly designed LD successfully demonstrates the high PCE of 73.6% which is comparable to the world record. Furthermore, high efficiency of 66.6% is obtained even at high injection current of 25 A by extension of cavity length based on optimized vertical design. The practical output power is successfully increased.

A high-speed continuous processing of carbon fiber reinforced plastic (CFRP) has been demonstrated using a 3-kW single-mode fiber laser and galvanometer scanner. The 3.1-mm-thick thermoset CFRP has successfully been cut with 100 scans at a scanning speed of 13 m/s. The effective cutting speed was 7.8 m/min. The laser was scanned continuously at a time interval of less than 20 ms. The surface was in good condition with a heat-affected zone (HAZ) of 97 μm on average. The test results indicate the high power continuous wave (CW) single-mode fiber laser can be used for high-speed CFRP processing.

In this paper a broadband millimeter-wave array antenna has been designed at 60-GHz band to be used in millimeter-wave small cell modules. An aperture coupled patch antenna has been used with inverted patches and air gap introduced between ground and patches. Some unfed patches (dummy patches) are applied for obtaining high gain. The performance of the antenna is dependent on the air gap,  dummy patches and the thickness of the upper substrate. The air gap has been tuned and the performance has been compared. The antenna shows 55 GHz to 65 GHz bandwidth for |S11| < -10 dB and very flat peak gain w.r.t. frequency for a single antenna. Peak gain for the single array is obtained 10 dBi. Beamforming with 16 such antennas has been shown to steer the beam ±50 deg at a loss of less than 3 dBi.