Study On Optical Sensors Based On Photonic Crystal Nanobeam Cavities

Among many types of micro/nano resonators,the photonic crystal nanobeam cavity(PCNC)has been widely used in low-threshold lasers,optical sensors,optical switches,cavity mechanical systems and other micro/nano photonic devices in recent years due to it has a very high quality factor and a very small mode volume,and has the advantages of small size,low power consumption,simple structure,easy preparation and easy coupling with optical waveguides and other unique advantages.On the other hand,optical sensors are widely used in environmental monitoring,biomolecule detection,food inspection,and so on.It is very important to study the principle and applications of optical sensors in depth and to develop new optical sensors with high sensitivity and high stability.And thus it is the starting point of this paper to search for new types of optical sensors with high sensitivity and high reliability based on photonic crystal nanobeam cavities.In this paper,we first introduce the photonic crystal and the photonic crystal nanobeam cavity,and illuminate the research status and development of the optical sensors based on the photonic crystal nanobeam cavities at home and abroad.Then,the main calculation methods used in this paper,such as the plane wave expansion method and the time domain finite difference method,are introduced.At the same time,some important parameters used to describe the optical performances of photonic crystal nanobeam cavity and to describe the sensing performances of optical sensors,such as the quality factor,mode volume and sensitivity,are calculated and discussed.In this paper,we propose and study a new type of optical sensor based on slotted fishbone-like photonic crystal nanobeam cavity.We used the plane wave expansion method to analyze the photonic band structure of the periodic waveguide structure of the slotted fishbone-like photonic crystal nanobeam.The optimized structural parameters with high photonic bandgap are obtained.Based on these optimized parameters,we used the mode matching theory to design a new type of optical sensor based on the slotted fishbone-like photonic crystal nanobeam cavity,and used the time domain finite difference method to study its optical properties and sensing performances.We designed a new type of optical sensor with high quality factor and sensitivity,and at the same time its mode volume is very small.The sensitivity reaches about 560 nm/RIU,the quality factor reaches 4.28×105,and the mode volume is 0.0248(?/n)3,meaning that our proposed optical sensor has very good optical properties and sensing performances.It is expected to have a very wide range of applications.In addition,in order to lay a good foundation for future experimental research,we also explored the practical applications of photonic crystal nanobeam cavity in optical sensors.Through the research of this paper,it is expected to provide guidance for the practical preparation of optical sensors with high sensitivity and high reliability based on slotted fishbone-like photonic crystal nanobeam cavity and other new photonic crystal nanobeam cavities.And also to lay a good foundation for the realization of the arraying,multi-channel and multi-purpose optical sensors.