The ChAMP program has been investigating the use of phase change materials in integrated silicon photonics to build reconfigurable optical routers.

The concept is to use a pixelated pattern of phase change chalcogenide material on top of a multimode interference waveguide (MMI) to guide light towards a selected output.

The pattern would be written by a laser incident from above in the first instance, targeting electrical switching in further work. Different patterns would yield different power splitting between the outputs, creating an reconfigurable optical switch/router.

Initial investigations showed the commonly used phase change chalcogenide, GST, had too high absorption loss for this to be practical so we developed two new phase change chalcogenide, based on Sb2S3 and Sb2Se3 with very low losses in both phases at 1550nm. These have been characterised and the MMI devices fabricated and simulated successfully. Testing is ongoing.