Semiconductor Optical Amplifier (SOAs) Developments

In October (2011) — Fujitsu Limited and Fujitsu Laboratories Limited announced the development of optical amplifier technology for use in optical access systems that link subscribers to central offices. The new optical amplifier technology has the ability to quadruple the splitting number and double transmission distance. (Details of these technologies were presented at the 37th European Conference and Exhibition on Optical Communication Conference, held in Geneva, Switzerland in September 2011).

According to Fujitsu, the use of optical aggregation networks, in which optical signals between a central office and many subscribers are optically passed along, rather than converted into electrical signals, has been proposed as one way to reduce the constantly growing amount of electrical power consumed by networking equipments.

Although passive optical networks (PONs), which increase transmission speeds in both downstream and upstream from the prevailing speed of 1 Gbps to 10 Gbps, are now starting to be deployed commercially, there are constraints in using them for optical aggregation networks because the number of optical network terminals (ONTs) for the most commonly used PON is typically limited to 32 connections and its transmission distance is also limited around 20 km.

To address these constraints, especially in upstream bursts, Fujitsu and Fujitsu Laboratories have developed the following three technologies: 

1. SOA-based Burst-mode optical amplifier technology
2. Integrated SOA-array module fabrication technology
3. SOA chip fabrication technology enabling un-cooled operation

These three technologies, used together, make it possible to quadruple the splitting number in an optical access system and double the transmission distance between the central office equipment and the terminal equipment. This makes it possible for a next-generation optical access system to be used as an optical aggregation network at low cost and with low power consumption requirements, paving the way for cloud infrastructure.

This makes it possible for a next-generation optical access system to be used as an optical aggregation network at low cost and with low power consumption requirements, paving the way for cloud infrastructure. The research results achieved by the Commissioned Research of National Institute of Information and Communications Technology (NICT) have been applied to portion of this work.

The three technologies that Fujitsu and Fujitsu Laboratories have developed make it possible to implement improved upstream burst transmission characteristics, which needed to expand the scope of optical access systems. This, in turn, quadruples the number of optical network terminals (ONTs) an optical access system can support, and doubles the transmission distance between the central office's equipment; optical line terminal (OLT) and ONT.