Research advances of photonic crystal gas and liquid sensors

The discovery of photonic crystal (PhC) has realized humanʹs dreams of manipulating and controlling photons. More and more researchers show great interests in the properties and application technologies of PhC, and many novel optical sensors have been proposed based on the novel structure and unique optical properties of PhC. Not only does it provide a potential for high sensitivity and flexible sensor design, but also opens up a new way to design micro sensors and integrated optical circuits. In this paper, research advances of PhC gas and liquid sensors are presented. Because of the diverse structure types of PhC, many unique and important properties such as photonic band gap, photonic localization, slow light based on PhC are discussed. According to these sensing properties, the theory, structural parameters of PhC and the performances of each kind of application in sensors are introduced in detail. Finally, the key problems of PhC in sensing technology are concluded and the future research directions are put forward.