Optical research boosted

The low yield of optical semiconductor processing, compared with today's silicon industry, is stalling progress in major markets such as ultra-high bandwidth communications networks for enterprises and homes.

Glasgow-based Intense is now fabricating chips that integrate up to 100 or more multi-function optical components on a single die. This integration demonstrates the high yields that can be achieved with the company's quantum well intermixing (QWI) process.

The breakthrough provides a platform for the reliable fabrication of optical chips that deliver major cost and size reductions in applications such as optical networking, printing and defence.

The process achieves reliable yields when fabricating multiple optical functions onto a chip, because - unlike regrowth-based compound semiconductor processes - it fabricates all the component elements in a single stage.

This makes it possible for OEMs to conceive system architectures based on new highly-integrated optical components that achieve much more than today's laser-and-modulator combinations.

The chip is a GaAs laser array operating at 980 nm, the wavelength for EDFA pumping. Each device in the array is individually addressable, and delivers >220 mW at the output facet. Two further passive waveguide components are integrated on either side of each laser element - providing serial integration in each channel, which further improves the yield by raising the threshold for catastrophic optical damage (a common laser failure mode), and relaxing the mechanical cleaving and packaging alignment tolerances.

Such an array could be used to lower the costs of building EDFA pumps for metro optical networks.