Nature Materials. 2014 Sep 28.
Healy N (1), Mailis S (1), Bulgakova NM (2), Sazio PJ (1), Day TD (3), Sparks JR (3), Cheng HY (3), Badding JV (3), Peacock AC (1).1Optoelectronics Research Centre, University of Southampton, Highfield, Southampton SO17 1BJ, UK.
21] Institute of Thermophysics, SB RAS, Novosibirsk 630090, Russia  HiLASE, Institute of Physics ASCR, 18221 Prague, Czech Republic.
3Department of Chemistry and Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
For decades now, silicon has been the workhorse of the microelectronics revolution and a key enabler of the information age. Owing to its excellent optical properties in the near- and mid-infrared, silicon is now promising to have a similar impact on photonics. The ability to incorporate both optical and electronic functionality in a single material offers the tantalizing prospect of amplifying, modulating and detecting light within a monolithic platform. However, a direct consequence of silicon‘s transparency is that it cannot be used to detect light at telecommunications wavelengths. Here, we report on a laser processing technique developed for our silicon fibre technology through which we can modify the electronic band structure of the semiconductor material as it is crystallized. The unique fibre geometry in which the silicon core is confined within a silica cladding allows large anisotropic stresses to be set into the crystalline material so that the size of the bandgap can be engineered. We demonstrate extreme bandgap reductions from 1.11 eV down to 0.59 eV, enabling optical detection out to 2,100 nm.
The authors demonstrated a breakthrough technique that offers the first possibility of silicon detectors for telecommunications which may have significant impact in the photonics field.