High-resolution and fast-response optical waveguide temperature sensor using asymmetric Mach-Zehnder interferometer structure

Abstract We propose and demonstrate a high-resolution and fast-response optical waveguide temperature sensor based on asymmetric Mach-Zehnder interferometer (MZI) structure. The sensing region is composed of an asymmetric MZI structure, which consists of two different kinds of cores formed with commercial polymer materials EpoClad and Norland optical adhesive 73 (NOA 73), respectively, in the two arms. Due to the higher thermo-optic coefficient of NOA 73, the phase changes of the two MZI arms are different with the temperature which in turn induces output optical power variations, enabling simple and real-time temperature detection. The sensor exhibits a large sensitivity of -1.685 ℃-1, high resolution of 1.48 × 10-3 ℃ and fast response time of about 510 μs. The advantages of high sensitivity and resolution, low-cost, competent integration and compatible with most biological assays make the designed sensor potential application in temperature detections of molecular analysis, biotechnology and chemical synthesis.