James Phillip Luther

Multicore optical fiber and connectors for high bandwidth density, short reach optical links

Multicore fiber technology can play a key role in very high bandwidth density optical interconnects that will be needed for short range communications in next-generation data centers and high performance computers.

High-speed, bi-directional dual-core fiber transmission system for high-density, short-reach optical interconnects

A complete single mode dual-core fiber system for short-reach optical interconnects is fabricated and tested for high-speed data transmission. It includes dual-core fibers capable of bi-directional data transmission, dual-core simplex LC connectors, and fan-outs. The transmission system offers simplified bi-directional traffic engineering with integrated bidirectional transceivers and compact system design, utilizing simplex dual-core LC connectors that use half the space while increasing the bandwidth density by a factor of two. The fiber has two cores that are compatible with single mode fiber and conforms to the industry standard outer diameter of 125 μm. This reduces operational complexity by reducing the size and number of fibers, cables and connectors. Measured OTDR loss for both cores was 0.34 dB/km at 1310 nm and 0.19 dB/km at 1550 nm. Crosstalk for a piece of 5.8 km long dual-core fiber was measured to be below -75 dB at 1310 nm, and below -40 dB at 1550 nm. Both free-space optics fan-outs and tapered-fiber-coupler based MCF fan-outs were evaluated for the transmission system. Error-free and penalty-free 25 Gb/s bi-directional transmission performance was demonstrated for three different fiber lengths, 200 m, 2 km and 10 km, using the complete all-fiber-based system including connectors and fan-outs. This single mode, dual-core fiber transmission system adds complementary value to systems where additional increases in bandwidth density can come from wavelength division multiplexing and multiple bits per symbol.

The use of multi-fiber ferrules in FTTP applications

With the long-awaited arrival of the fiber-to-the-premises initiative (FTTP), there has been a focused effort to devise the most effective solutions for construction of the needed outside plant infrastructure. The outcome of this activity is a preconnectorized solution for the distribution network based on the MT ferrule. The main advantages of the MT-based solution include lower initial capital investment per home passed, speed of deployment, and a reduced need for precise field measurements of the cable plant. The lower capital requirement for service providers results from the ability to delay in time the placement of the network access point terminal with its associated adapters and pigtails. The speed of deployment advantage comes from the compact nature of the resulting tap point. An overmold process is used to provide a small, flexible solution that works well with outside plant installation practices. Due to its flexibility, it can be routed easily. The reduced need for field tap location measurement accuracy stems from the fact that one can now install the cable and measure exactly where the final terminal needs to be because of a flexible tether length that is part of the design. An additional advantage attributable to the use of the tether is the ability to use whatever enclosure solution makes sense in a given application without regard for whether or not it passes through a sheave wheel. The proposed paper will cover the evolution of the terminal distribution system for FTTP networks and discuss the capability and performance of the new MT-based system. Test data on a new multifiber ferrule based connector to Telcordia GR-3120 will be presented. Additional testing of the completed assembly to Telcordia GR-3122 will be presented.