Kota Shikama

409-Tb/s + 409-Tb/s crosstalk suppressed bidirectional MCF transmission over 450 km using propagation-direction interleaving

We demonstrate bidirectional transmission over 450 km of newly-developed dual-ring structured 12-core fiber with large effective area and low crosstalk. Inter-core crosstalk is suppressed by employing propagation-direction interleaving, and 409-Tb/s capacities are achieved for both directions.

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.

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.

Wavelength selective switch array employing silica-based waveguide frontend with integrated polarization diversity optics

We propose a waveguide frontend with integrated polarization diversity optics for a wavelength selective switch (WSS) array with a liquid crystal on silicon switching engine to simplify the free space optics configuration and the alignment process in optical modules. The polarization diversity function is realized by the integration of a waveguide-type polarization beam splitter and a polarization rotating half-wave plate in a beam launcher using silica-based planar lightwave circuit technology. We confirmed experimentally the feasibility of using our proposed waveguide frontend in a two-in-one 1 × 20 WSS. The experimental results show that the fabricated waveguide frontend provides a polarization diversity function without any degradation in optical performance.

Spatial and planar optical circuit for flexible ROADM

A high port count wavelength selective switch (HPC-WSS) is a key component when constructing colorless, directionless, and contentionless ROADM because it provides increased flexibility and scalability. We have been developing HPC-WSSs by combining a waveguide-based optical frontend and free-space optics, which we call a spatial and planar optical circuit (SPOC) platform. In this paper, we present an HPC-WSS and a low-loss transponder aggregator based on a SPOC platform, and we also describe the reliability of the frontend, which is a key enabler for the SPOC platform.