The Research Of Terahertz Sensing Method Based On Photonic Crystal Slab

It is very necessary to detect specific biochemical molecules in a sample in the field of biochemical sensing.Since most biochemical molecules especially organic molecules exhibit unique and obvious fingerprint characteristics in the terahertz regime,and terahertz wave has many characteristics such as low energy,non-ionization,and high penetrability,the terahertz-based biochemical sensing method has unique advantages and has gradually become a research hotspot.The photonic crystal slab is a kind of artificially designed periodic structure,which can enhance the interaction between terahertz wave and target such as biochemical molecules,thereby improving the sensitivity of sensor.The application of photonic crystal slab to terahertz sensing provides an idea for biochemical molecular detection.Two kinds of terahertz photonic crystal sensors with high sensitivity are designed in this paper,which can realize the qualitative identification and quantitative analysis of trace substance.The main research work in this paper is described as follows:(1)A terahertz refractive index sensor based on a two-dimensional photonic crystal slab is designed.Based on good sensitivity of guided mode resonance to the surrounding environment,this sensor can effectively detect liquids with different refractive indices.The sensor has a high quality factor at resonance and its value can reach up to 63.75.In the working range,there is a good linear relationship between the resonant frequency of the sensor and the refractive index of the liquid,and liquids can be detected by the relationship.The sensor has a high detection sensitivity and its value can reach up to 23.08 GHz/RIU.The sensitivity of the sensor can be further improved by optimizing the structural parameters of the photonic crystal slab.Miniaturized sensors are beneficial to integration of portable sensors.(2)A terahertz fingerprint sensor based on a photonic crystal microcavity is designed.The photonic crystal microcavity is composed of two parallel photonic crystal slabs.The sensor has a high quality factor at resonance which is 529.A strong and uniform electric field enhancement is obtained in the middle position of the sensor at resonance,which is very helpful for sensor detection.The results show that the target can be distinguished from the non-target according to whether the transmittance peak is attenuated or not and the qualitative analysis of the target can be realized based on the attenuation of the transmittance peak.For trace amounts of lactose with a thickness of 0.5 ?m,compared with the detection method that Teflon is taken as the sensing substrate,the sensor can detect the trace substance and increase the detection effect by 31 times.(3)The machining and test scheme of the terahertz photonic crystal sensor are designed.The machining technology of the sensor is mainly based on semiconductor processing technology,including photolithography technology,coating technology,stripping technology and reactive ion etching technology.Test scheme of the sensor includes test equipment and test method.The machining and test scheme of the terahertz sensor based on photonic crystal slab gives an idea for the field from theoretical research to application.