Temperature Sensitivity of a Waveguide Young Interferometer

The temperature sensitivity of a waveguide Young interferometer is investigated experimentally and using numerical simulations. With different materials on the two arms of the interferometer, the output phase is linear with temperature, making the device suitable for on-chip temperature sensing. A symmetric interferometer with the same material on both arms is almost insensitive to hotspots and temperature steps applied to the bottom of the substrate, while it is still sensitive to the asymmetric heating of the top surface. For biological or chemical sensing, it must be assured that any heating of the top surface, e.g. from liquid or gas flow, is symmetric with respect to the interferometer, both for asymmetric and symmetric devices. For a 20mm long device, the difference in temperature between the two arms must be limited to a few millikelvin in order not to influence the performance of the device.