Chip‐Integrated Gas Sensors with Tunable Diode Laser Absorption Spectroscopy

Abstract Optical gas sensors utilizing tunable diode laser absorption spectroscopy (TDLAS) have been a prominent research focus over the past decades because of their significant potential for detecting toxic and flammable gases, monitoring greenhouse gases, and diagnosing diseases. Among current optical sensing platforms, photonic chips are particularly promising due to their ability to integrate multiple optical functions onto a single chip using CMOS‐compatible fabrication. Furthermore, many integrated optical materials, such as silicon, silicon nitride, and chalcogenide glass, can be extended to the mid‐infrared band, facilitating the development of sensitive volatile organic compounds (VOCs) fingerprint sensors. In the past decade, tremendous novel gas sensing techniques of chip‐integrated gas sensors with TDLAS have emerged quickly, driven by enormous demands from the internet of things, wearable devices, and point‐of‐care diagnosis. In this paper, basic knowledge, state‐of‐the‐art techniques, and cutting‐edge applications of chip‐integrated gas sensors are comprehensively reviewed with TDLAS, and their prospects. It is hoped that this review can serve as a helpful reference for researchers in fields of gas sensing, laser spectroscopy, integrated optics, and their applications.