Mitsuhiro Iwaya

High bandwidth optical interconnection for densely integrated server

We developed optical interconnect technologies, i.e., an optical mid-plane, high-density connector, and a compact transceiver for future servers that enable high-bandwidth and dense integration. Using these technologies, 1500 optical connections and 37.5 Tb/s of bandwidth were built in a blade-server form factor.

Optical interconnect architecture for servers using high bandwidth optical mid-plane

We describe an interconnect architecture that utilizes high bandwidth optical mid-plane. Enabling technologies for high density optical mid-plane are discussed. We developed a prototype to determine the feasibility. The results showed proposed architecture is practical.

Development of MPO type 8-multicore fiber connector

We developed MPO type 8-MCF (56-core) connector. Rotational alignment with alignment member and absorption of protrusion difference using compressive strain were adopted. Fabricated 8-MCF connector demonstrated all core PC and connection loss <; 0.7 dB.

MPO Type 8-Multicore Fiber Connector With Physical Contact Connection

We developed a MPO type 8-multicore fiber (MCF) connector using single mode 7-core MCF and realized physical contact (PC) with return loss more than 40 dB and low connection loss less than 0.85 dB in all 56 cores. To simplify the rotational alignment process for each MCF, we developed the rotational alignment method using alignment member and realized rotational alignment accuracy within ±1°. To reduce necessary pressing force for PC connection of all cores in all MCFs, we utilized compressive strain of MCF cladding for the absorption of height difference among MCFs and polishing for bare MCF to reduce necessary pressing force for a pair of MCFs. Fabricated 8-MCF connector demonstrated all cores PC with pressing force of 18 N.

No-polish elastic optical multifiber connector for optical interconnection

An elastic optical multifiber connector compatible with a standard mechanically transferrable connector was realized. The elastic connector has N-shape folded frame parts which are elastically deformable of 100 μm. Physical contact connections between no-polish fibers and a film-waveguide were confirmed. The average insertion loss of the cables terminated at one side with an elastic connector shows 0.16 dB which is almost same as those terminated at both ends with mechanical transferrable connectors. The durability for 250 times mating/demating tests in a mid-plane connector housing were also confirmed. Furthermore, the laser-cleaved fiber facets have smooth surfaces and convex shapes like those of polished connectors. Using the connector and the process, physical contact connections between no-polish fibers were achieved.

Development of low-cost polish-less optical multifiber backplane connector

We developed a novel low-cost polish-less elastically deformable optical multifiber backplane connector. The ferrule deformation and fibers buckling were enabled to cancel the variation in the lengths of unpolished cut fibers. We confirmed the physical contact connection between unpolished cut fibers in the ferrule and a polymer waveguide in a connector for polymer-waveguides connected with mechanical transfer connector (PMT) ferrule. The connection loss is almost the same as that between a conventional polished mechanical transfer (MT) ferrule and the PMT ferrule. We prepared a connector housing to mount the ferrules on a backplane/midplane. The insertion loss and return loss results in the housing show no degradations during 200 mating/demating tests, and there were no fiber breakages or damage to the waveguide core.

High-density multi-lane connectivity for optical interconnect

With the rapid increase of data traffic the demand for high density optical interconnect is getting greater than ever. In this manuscript a few examples of the recent technologies and developments in the field are introduced.

Development of low-cost elastic optical multifiber connector for optical interconnection

We propose and demonstrate a novel low-cost elastic optical multifiber connector to realize optical interconnections. The ferrule deformation and fibers buckling are enable to cancel the variation in lengths of unpolished cut fibers. We confirmed a physical contact connection between the ferrule and a PMT ferrule. The connection loss was almost the same as that between a conventional polished MT and the PMT. Also, we prepare A connector housing for mounting the ferrules on a MP is prepared. The insertion loss and return loss measurements in the housing shows no degradations during 250 mating/demating tests.

MT type connector for 2×6 multicore fibers

MT type connector for 12 multicore fibers arranged in 2×6 array is developed. Rotational alignment precision within ± 0.9 degree is realized by employing alignment member with two fiber holes. Low connection loss less than 0.8 dB is also realized in all 84 cores.

Low-loss connections between no-polish optical fibers in elastically deformable connectors

Low-loss connections between no-polish optical fibers were realized by using a combination of elastically deformable connectors and a laser cleaving process. The elastic connectors have an elastically deformable mechanism, which enables one to cancel out variations both in the fiber length in a fiber ribbon and in the fixed positions of the fiber ribbons in the connectors. A laser cleaving process was employed to cleave no-polish fiber facets. The fiber facets show slightly protruded convex shapes, which were almost the same as those of the polished facets. We confirmed that physical contact connections between the laser-cleaved no-polish fibers in the elastic connectors were realized. The average insertion loss and return loss of cables including connection between the no-polish fibers in elastic connectors were 0.19 dB and 23.4 dB, respectively. The values were almost the same as those of cables including connection between polished fibers in mechanically transferable connectors. Furthermore, the durability of the connections between the elastic connectors over 250 repeated mating/dematings in a high-density mid-plane connector housing was also confirmed.