Integrated optical hydrogen and temperature sensor on silicon-on-insulator platform

Abstract

A compact, reliable and safe hydrogen sensor is required for the existing and emerging applications of hydrogen including aerospace and fuel cells. An optical sensor is an attractive option for hydrogen sensing because of its compactness, immunity from electromagnetic interference, and inherent safety. In this work we present the results of experimental demonstrations of a Pd-based hydrogen sensor and a ring resonator based temperature sensor on a siliconon-insulator (SOI) platform. The hydrogen sensor consists of a ridge waveguide with a very thin coating of palladium. The sensor response time is less than 10 seconds for 4% hydrogen concentration, and the sensor response was repeatable under hundreds of cycles of exposure to hydrogen. The response of the hydrogen sensor is affected by variation of temperature, and this effect must be considered in a real life application of the hydrogen sensor. To overcome this limitation we design and experimentally demonstrate a temperature sensor on SOI using a ring resonator, which shows good sensitivity over a wide range of temperature. The hydrogen sensor and the temperature sensor can be integrated on the same chip to implement a sensor capable of reliably measuring hydrogen concentration under varying temperature.