Temperature sensor with enhanced sensitivity based on silicon Mach-Zehnder interferometer with waveguide group index engineering.

We propose a highly-sensitive temperature sensor employing a Mach-Zehnder interferometer (MZI) based on silicon-on-insulator (SOI) platform. The waveguide widths in the two MZI arms are tailored to have different temperature sensitivities but nearly the same group refractive indices. A temperature sensor with an enhanced sensitivity of larger than 438pm/°C is experimentally demonstrated, which is over seven times larger than that of conventional silicon optical temperature sensor (about 60pm/°C for quasi-TM mode). Moreover, the sensor is easy to fabricate, only by a single mask, and no need of any polymer cladding, which makes it more robust, and can be used in lab-on-chip systems as a temperature monitor.