The Centre for Integrated Photonics (CIP) in the UK has unveiled details of a novel hybrid assembly technique that enables simple, yet highly reliable, integration of optical devices. CIP claims that its field-proven technique eliminates the expense of active alignment and provides a cost-effective platform for creating the sophisticated building-blocks required for advanced optical networking.
"Hybrid integration is an optimal way forward for many of the optical functions needed in advanced optical networks, but most of the assembly techniques in mainstream use today rely on highly skilled labour and expensive equipment, and do not scale," says Graeme Maxwell, CIP's vice-president of hybrid research and development.
Maxwell continued: "Our technique requires just passive assembly, yet provides very low insertion losses - making it possible to create single-module solutions for applications such as packet switches and signal regenerators."
The integration process involves plugging silicon daughterboards carrying individual optical components into a planar silica motherboard - all of which have precision-machined mating faces. The components themselves also employ simple interface modifications - namely mode expansion - and features to support precision cleaving.
The result, says CIP, is a hybrid photonic integration technique similar to that used for assembling electronic printed circuit boards - with the planar silica motherboard providing the equivalent of printed wiring.
CIP has developed and refined this assembly technique over 10 years. The process is optimized for low interface losses and ease of assembly, and doesn't involve any complex processing or etching. It's also highly scalable and applies equally well to two devices or large subsystems that integrate many component elements.
CIP has used the technique to manufacture numerous devices, such as the recentlyreleased 2R regenerator (see CIP's regenerators get ready for 40 Gbit/s), which it says is attracting a lot of interest from optical network developers. This device integrates a planar silica Mach-Zehnder interferometer and a monolithic quad semiconductor optical amplifier array to create a dual-channel 2R regenerator with just 1 dB loss at the daughterboard/motherboard interfaces.
The assembly technique evolved from considerable research and development undertaken by CIP during its history as part of BT, then Corning, and for the last two years as an independent photonic design and manufacturing consultancy. CIP offers the technology in a variety of forms to suit different applications and users. These include technology consultancy to support design-in, funded development programs and the provision of turnkey hybrid component solutions - such as its multichannel 2R regenerator.
"We believe this hybrid integration technique provides the performance, reliability and economy to address many of the sophisticated component functions necessary for advanced optical switched fabrics," adds Maxwell. "Among the potential applications are reconfigurable add-drop multiplexers, 2R and 3R signal regenerators, high-speed interconnect, packet switches, WDM PON devices and optical buffer memories. In each of these cases I expect our platform approach to offer considerable cost reduction and performance advantages over current component solutions and integration methods."