Cascaded ring resonator-based temperature sensor with simultaneously enhanced sensitivity and range.

We report a cascaded ring resonator (CRR) based, silicon photonic temperature sensor for simultaneous sensitivity and range enhancement. To achieve the dual enhancement, the proposed CRR temperature sensor employs two micro ring resonators with different temperature sensitivities and different free spectral ranges (FSRs). The differences in the temperature sensitivities and FSRs are obtained by tailoring the in-plane geometric parameters of the two ring resonators. The CRR temperature sensor was fabricated by using a single-mask complementary metal-oxide-semiconductor (CMOS)-compatible process. The experimental results demonstrated a temperature sensitivity of 293.9 pm/°C, which was 6.3 times higher than that of an individual ring resonator. The sensor was also shown to enhance the temperature sensing range by 5.3 times.