Temperature-Insensitive Integrated Optical Electric Field Sensor Based on Asymmetric Mach–Zehnder Interferometer

Abstract

The thermal bias drift problem induces poor stability of the operating point of integrated optical electric field sensor and thus large measurement errors in the practical applications. In this article, we have proposed a passive thermal compensation approach to an inherently temperature-insensitive integrated electric field sensor. Both theoretical analysis and experiments demonstrated that the thermal bias drift could be effectively suppressed by a combination design of waveguide width and length of the asymmetric Mach–Zehnder interferometer. Based on this new waveguide design, a temperature compensated electric field sensor with optimal geometrical parameters was fabricated. Its thermal bias drift was reduced from <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$-3.3^{\circ }/^{\circ }\text{C}$ </tex-math></inline-formula> to 0.23°/°C, more than ten times lower than the uncompensated conventional sensor. Furthermore, the maximum/minimum detectable electric fields are 2.5 and 200 kV/m, respectively, for measuring lighting impulse electric field, and a measurement error as low as 1.6% was achieved from 18 °C to 28 °C. These results are very encouraging for implementing practical integrated optical electric field sensing schemes.