Study On The Properties Of PCF And Its Polarization Beam Splitter Based On Compressed Structure

Nowadays,with the rapid development of science and technology,conventional optical fiber and optical devices have gradually exhibited the limitations of low data transmission efficiency and low capacity.Therefore effectively transmitting and processing data via highperformance optical fibers and devices is becoming an inevitable trend.Since the photonic crystal was first proposed in the 21th century,considerable attention has been paid to PCFs and photonic devices developed by its unique optical properties because of extensive application prospects.Currently,all optical information networks built by PCFs and photonic devices may be the reliable access to enlarging data capacities and improving transmission efficiencies.However,complex designs and mixed doping of various materials are used in order to improve the performances of PCF and optical devices in many researches,which will not only increase the fabrication difficulty,but also become a negative factor on its practical application in the future.Based on this background,for simplifying the structure design and improving the performances at the same time,high performance PCFs and polarization splitters with simplified compressed structures are proposed,and properties of these proposed PCFs and splitters are investigated by employing FEM:The propagation characteristics of the photonic crystal fiber with compressed hexagonal structure（CH-PCF）are studied.Only two sizes of circular air holes are used and the background material is quartz glass in this design.CH-PCF can basically achieve high birefringence of 10^-2 magnitude in the waveband of 1.05～2μm,which shows great polarization maintaining performance.At the wavelength of 1.31μm and 1.55μm,the nonlinear coefficients of X and Y polarization are better than 40W^-1·km^-1,respectively.The ultra-flattened dispersion of X and Y polarization can be achieved with the fluctuation of±3.4ps·nm^-1·km^-1 and±1.6ps·nm^-1·km^-1 within the waveband of 1.3～1.8μm,which cover the E+S+C+L+U bands.The propagation characteristics of the polarization beam splitter based on dual-core photonic crystal fiber with compressed hexagonal structure（DC-PCF）are investigated.Only three sizes of circular air holes are used in this design.DC-PCF can accomplish high birefringence of 10^-2 magnitude in the waveband of 1.25～2μm,which shows great polarization maintaining performance.At the wavelength of 1.55μm,the polarization beam splitter based on DC-PCF can accomplish an ultra short length of polarization beam splitter with 420μm,and the bandwidth of extinction ratio higher than 20dB is 33nm which cover the C band.The maximum extinction ratio is 69dB.The propagation characteristics of the polarization beam splitter based on dual-core photonic crystal fiber with "Circle-Rectangle" structure（CR-PCF）are analyzed.Only one size of circular air holes are used in this design.CR-PCF can realize high birefringence of 10^-2 magnitude in the waveband of 1.01～2μm,which shows great polarization maintaining performance.At the wavelength of 1.31 μm and 1.55μm,the polarization beam splitter based on CR-PCF can realize ultra short length of polarization beam splitters with 253μm and 151μm,respectively.The corresponding extinction ratio is -44.6dB and -51.5dB,and the bandwidth of extinction ratio lower than -20dB is 13nm and 16nm,respectively.