Comparative Study On Optical Properties Of New High Birefringence Photonic Crystal Fibers

Compared with conventional optical fiber,photonic crystal fiber?PCF?has special optical properties,such as single mode transmission without cutoff and multi-zero dispersion point characteristic,which has been called one of the top ten research hotspots with potential in the 21st century.The design structure of photonic crystal fiber is flexible,and the structure or parameters of the fiber can be adjusted to meet the requirements we need.For example,PCF with high birefringence can be used in optical communication and optical sensing.The highly nonlinear PCF has a broad application prospect in the fields of supercontinuous spectrum generation,optical soliton communication and optical switch.In recent years,different methods have been used for the design and optical simulation of photonic crystal fiber with special cladding structure,which provides a reliable theoretical basis for the manufacture of high-performance photonic crystal fiber.In this paper,according to the basic theory of PCF,two different types of PCFs are designed by using the finite element method,namely,the inner cladding elliptic hole PCF and the fully elliptic hole PCF.The theoretical analysis of the three-circle hole cladding PCF is carried out,and the performance exploration and application prospect of the simulation results are analyzed.The results show that:1.The inner cladding elliptic hole PCF is proposed,which the inner cladding are replaced by four elliptical air holes and two small circular air holes.The results show that by adjusting the ellipticity and small circular air hole parameters,the inner cladding elliptic hole PCF in the communication band can get higher birefringence 4.22×10-2 and negative dispersion.This new type of high birefringence PCF brings widely application prospect,such as light switch and polarization-maintaining optical fibre.2.The optical characteristics of the fully elliptic hole PCF are studied by changing the ellipticity,and the results show that the high birefringence 10^-11 orders of magnitude and positive dispersion values can be obtained at the communication band.The birefringence obtained by this new type of PCF is three orders of magnitude higher than ordinary optical fiber,which lays a new idea for obtaining high-birefringence photonic crystal fiber and can also be applied to compensate dispersion.3.In view of the grapefruit type optical fiber which has been manufactured and applied in practice,a three-circle hole cladding PCF model is established,and the theoretical analysis is carried out.When the set parameters were located in the communication band,8×10^-22 birefringence,76km^-1·W^-11 nonlinearity can be obtained,and the zero dispersion point appears in the near infrared region.On this basis,the first two kinds of photonic crystal fibers with different elliptical holes are compared and analyzed,and the similarities and differences between the fully elliptical hole PCF and the three-circle hole cladding PCF are summarized and analyzed.