Thermal tuning of planar Bragg gratings in silicon‐on‐insulator rib waveguides

The Bragg grating forms an essential element in optical telecommunication and sensing applications. In the case of integrated optics, it is necessary to incorporate the grating into a waveguide during device fabrication. Specifically for silicon photonics this process is deemed necessary to be compatible with standard processing technology. We have recently developed a method for the fabrication of Bragg gratings via self‐ion implantation of silicon‐on‐insulator (SOI) waveguides, such that the surface of the waveguide remains planar. This has significant benefits for a number of devices especially those requiring subsequent wafer bonding. Here we report work that shows the ability of these devices to be thermally tuned. As the waveguides are heated, a positive shift in the resonant wavelength is induced due to the temperature dependence of the index of refraction and thermal expansion of the silicon. The observed shift is 0.080 nm/degree, in good agreement with theoretical prediction. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)