Bookham unveils optical multiplexer/demultiplexer modules based on thin film filter technology

July 19, 2004 Santa Rosa, CA--Bookham Technology plc, a provider of optical components, modules and subsystems, has launched a new class of high channel count, scalable multiplexer/demultiplexer products based on thin film filter technology.

These new products give customers a low-cost, entry module with full expandability of up to 40 channels in DWDM networks. The same module can be used in both multiplexing/demultiplexing and in reconfigurable optical add/drop multiplexing (ROADM) applications. Upgrades can be handled in 8-10 channel increments in any wavelength order with minimal insertion loss increase.

"This is a major development in a market where world-class performance against cost is always an issue," said Dennis Derickson, Bookham's thin film applications engineer.

Optical filtering based on "banded architecture" arranges separate optical communications channels on a particular wavelength into groups and, instead of processing them one at a time, the filter processes the group, reducing overall footprint and optimising device efficiency and cost.

Based on proprietary AED III (Advanced Energetic Deposition, version III) technology, a new class of banded filters called "8 skip 0" and "10 skip 0" have been introduced for use in 100-GHz channel spacing DWDM systems. These filters enable 8 or 10 channels at a time to be filtered without skipping, or sacrificing, the neighbouring channels. This capability is more than double the level of the industry's more commonplace four-channel versions.

Bookham's thin film design team leader, Loren Stokes, explained the significance of the development: "Four years ago, '4 skip 1' (that is, four channel filtering with the loss of one adjacent channel, due to signal degradation/interference at the filter's edge) banded filters were at the forefront of design. By 2002/2003, Bookham and other companies had introduced '4 skip 0' filters to the market, eliminating the need for skipped channels. Bookham's latest introduction has achieved both '8 skip 0' and '10 skip 0' filters."

These new filters allow multiplexers and demultiplexers to be built with a simplified, flexible, and lower cost architecture. The product range is now available and is currently being sampled with a number of customers.