Locally erasable Bragg gratings in silicon waveguides
Tuesday 7 June 2011
Dr Renzo Loiacono from the Silicon Photonics Group and co-workers from the Advanced Technology Institute, Intel Corporation and Numonyx have experimentally demonstrated laser erasable germanium implanted Bragg gratings in silicon.
Bragg gratings are formed in a silicon waveguide by ion implantation induced amorphization, and are subsequently erased by a contained laser thermal treatment process. The project involved a close collaboration between the Photonics group (design and optical characterisation of gratings), Nymonyx (fabrication of waveguides), the Ion Beam Centre (germanium implantation), the Nanoelectronics centre (laser annealing), and Intel Corporation (r) (technical consultation and funding) and has resulted in world's first locally erasable gratings in silicon. A Bragg grating is a periodic structure that reflects particular wavelengths and transmit all others. It can be used as an optical filter or a reflector. Conventionally, Bragg gratings are etched onto a silicon waveguide and thus change the planarity of the surface. The concept of implantation of gratings retains the planarity of the surface and offers a possibility to erase gratings, if necessary, by local laser annealing. This can have a significant impact in developing a commercially viable photonic technology.
The paper is available at:
http://www.opticsinfobase.org/oe/abstract.cfm?uri=oe-19-11-10728