Research On Sensing Characteristics Based On Filled Photonic Crystal Fiber

Photonic crystal fibers have many advantages,such as non cut-off single mode transmission,good nonlinearity,high birefringence,and so on.Moreover,the air holes of photonic crystal fiber cladding are periodically arranged.Photonic bandgap photonic crystal fiber core is also air hole structure,so all kinds of materials that can be filled in the PCF air hole are used to produce photonic crystal fibers with various optical properties.It has been reported a variety of photonic crystal fiber filling materials,such as temperature,electric field,electric liquid crystal tunable filler(single hole filling liquid crystal,liquid crystal double core filling,liquid core photonic crystal fiber),magnetic fluid filled photonic crystal fiber filled photonic crystal fiber and so on.On this basis,some innovative methods and methods have been adopted in this paper,and the relevant work has been carried out.The main contents of this article are as follows:1.The main characteristics of photonic crystal fiber and the development background of filling photonic crystal fiber are introduced.2.The background of the development of photonic crystal fiber sensor technology is introduced,and then the grating type photonic crystal fiber sensing technology and its theory are briefly described.Finally,the sensing principle of the interferometric photonic crystal fiber sensor is analyzed in detail,including photonic crystal fiber sagnc interference,MZ interference and FP interference sensor.Theoretical paving for the design of the sensor below.3.A photonic crystal fiber MZ refractive index sensor based on complete filling of ethanol is proposed.The structure uses photonic crystal air hole collapse method to achieve MZ interference of photonic crystal fiber.When light first passes through the first collapse area,it will excite high order mode and make it enter the cladding,and intermode interference will be carried out in the next collapse area.When the ethanol is filled into the photonic crystal fiber,the effective refractive index of the cladding will be influenced by the refractive index of the optical fiber,and then the interference spectrum is drifted.When the refractive index of the sensor is changed from 1.335 to 1.350,the transmission spectrum is 5.8nm,and the sensitivity of the refractive index of the sensor is 386.66nm/RIU.4.A new type of Sagnac fiber sensor based on alcohol asymmetric filling photonic crystal fiber is proposed.The sensor first corroded the photonic crystal fiber and collapsed the air hole,and then filled with alcohol to obtain the asymmetric photonic crystal fiber.Then the structure is connected to the Sagnac interference ring,and the interference effect of Sagnac is realized.When the external temperature changes,the thermal expansion effect of alcohol will lead to the change of the birefringence of photonic crystal fiber,so that the peak of the interference spectrum will change with the change of temperature.After adding transverse stress to photonic crystal fiber,strain changes of photonic crystal fiber will also lead to the change of the self birefringence and the drift of the interference spectrum.The experimental results show that the interference spectrum will shift to blue with the increase of temperature or transverse stress.The temperature sensitivity is 0.1864nm/and the transverse stress sensitivity is 0.5233nm/N.The sensor has high sensitivity to temperature and stress.At the same time,the structure has the advantages of high stability,anti electromagnetic interference and easy to build.It provides a new method for obtaining birefringence in ordinary photonic crystal fibers.In addition,a practical temperature and stress detection system is set up by using the new sensor.The relative error of the experiment is less than 2%.