Hybrid assembly integrates optical devices

The Centre for Integrated Photonics (CIP) in England has announced a novel hybrid assembly technique that offers a simple yet reliable method of integrating optical devices.

The technique eliminates the expense of actively aligning devices - the process in common use today - providing a platform for creating the 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 VP of Hybrid Research and Development.

"Our technique requires passive assembly, yet provides low insertion losses - making it possible to create single-module solutions for applications such as packet switches and signal regenerators."

The technique integrates by means of plugging silicon daughterboards carrying individual optical components into a planar silica motherboard - each having precision-machined mating faces. The components themselves also employ simple interface modifications - namely mode expansion - and features to support precision cleaving.

The result turns hybrid photonic integration into a similar form of process to that used for assembling electronic PCBs - with the planar silica motherboard providing the equivalent of printed wiring.

The assembly technique has been developed and refined over about 10 years and has been highly optimised for low interface losses and ease of assembly and does not involve any complex processing or etching. The technique is also highly scalable and applies equally well to two devices or a large subsystem integrating many component elements.

CIP has manufactured numerous devices using the technique, such as its 2R regenerator - a recently announced commercial device. On this example of its hybrid integration, the component integrates a planar silica Mach-Zehnder interferometer (MZI) and a monolithic quad semiconductor optical amplifier (SOA) array to create a dual-channel 2R regenerator with just a 1 dB loss at daughterboard/motherboard interfaces.