A failure recovery system utilizing a multi-core fiber (MCF) link with field programmable gate array-based optical switch units was developed to achieve high capacity and highly reliable optical networks in access areas. We describe the novel MCF link based on a multi-ring structure and a protection scheme to prevent link failures. Fan-in/ -out devices and connectors are also presented to demonstrate the development status of the MCF connection technology for the link. We demonstrated path recovery by switching operation within a sufficiently short time, which is required by ITU-T. The selection of a protecting path as a failure working path was also optimized as the minimum passage of units for low loss transmission. The results we obtained indicate that our proposed link has potential for the network design of highly reliable network topologies in access areas such as data centers, systems in business areas, and fiber to the home systems in residential areas.
For a multi mode fiber optical link, a high speed silicon photonics receiver based on a highly alignment tolerant
vertically illuminated germanium photodiode was developed. The germanium photodiode has 20 GHz bandwidth and
responsivity of 0.5 A/W with highly alignment tolerance for passive optical assembly. The receiver achieves 25 Gbps
error free operation after 100 m multi mode fiber transmission.
Single-mode InGaAsP QW lasers with wavelengths of 700 to 730 nm are demonstrated. These lasers are attractive as
light sources for medical and biological applications because biological tissues are relatively transparent in the near-infrared
range. The laser has a 2-micrometer-wide ridge-waveguide structure and achieves single-mode 100-mW CW
operation at 80°C with an extremely low operating current of 130 mA and a high characteristic temperature of 182 K.
These InGaAsP lasers enable innovative solutions in demanding applications by means of a light source with a compact
size and low cost.