The use of materials with a high thermo-optic coefficient would lead to significant improvements in energy consumption and thermal management in optical switching and sensing devices. Most liquids rank among materials having the highest thermo-optic coefficients, along with polymers and silicon. We have developed technology to directly incorporate liquids in integrated silica-on-silicon photonic device structures. Using this technology, we demonstrate experimentally integrated Mach-Zehnder interferometers (MZIs) comprising a liquid-core waveguide in one of the interferometer arms. Because of the large differential between the thermo-optic coefficients of silica and the liquid medium, the output of this device can be modulated through the thermal control of the device chip. A high contrast ratio (more than 20 dB) in the interferometer output modulation is obtained, demonstrating that the optical loss is well balanced between the two interferometer paths. The temperature variation required to fully cycle the output state is less than 0.5 degrees Celsius. Designs for low power thermo-optic switches based on these MZI structures with integrated heating electrodes are presented. The inclusion of a second liquid-core waveguide in the "passive" interferometer arm can enable athermal and polarization insensitive devices.

Date Published: 12 August 2008
PDF: 8 pages
Proc. SPIE 7099, Photonics North 2008, 70990Z (12 August 2008); doi: 10.1117/12.804597

Published in SPIE Proceedings Vol. 7099:
Photonics North 2008
Réal Vallée; Michel Piché; Peter Mascher; Pavel Cheben; Daniel Côté; Sophie LaRochelle; Henry P. Schriemer; Jacques Albert; Tsuneyuki Ozaki, Editor(s)