A new optical signal routing scheme for linear lightwave networks

We propose a new scheme for optical signal routing within linear lightwave network (LLN) subnets. The LLN is a fiber optic network which performs only linear operations on optical signals: power combining, splitting and possibly linear optical amplification. The LLN can be partitioned into several subnets where each subnet is a tree providing full broadcast among all stations connected to it. We study the synchronization problem that exists in these subnets which prevents efficient implementation of time division multiple access schemes for sharing a common broadcast medium. A solution to this problem is proposed, based on a new optical signal routing scheme, called rooted routing. The impact of rooted routing on power losses is analyzed, and an approach for minimizing power loss in LLNs with rooted routing is presented. It is shown that when link and excess losses are small, rooted routing power budget can be made close to the power budget yielded by the original, shortest path routing scheme. It is also shown that rooted routing power budget can be significantly improved using a single optical amplifier.