Research On Birefringence And Bandgap Of Several Kinds Of Photonic Crystal Fibers

Photonic crystal fiber (PCF) has become more attractive because of their unique properties, such as singular dispersion, high birefringence and unique bandgap characteristics. Photonic crystal fiber (PCF) can be classified as total internal reflection PCF and photonic bandgap (PBG) PCF. In this paper, the properties of high birefringence and bandgap for different PCF have been studied, the major work is as follows:Firstly, A kind of double-cladding photonic crystal fiber (DC-PCF) with high birefringence and two zero-dispersion wavelengths is proposed in this paper. It is found that the birefringence of DC-PCF with inner cladding air holes pitch 1.0μm and diameter 0.8μm is 1.001×10^-2 in optical communication band 1.55μm wavelength by the multipole method. It is demonstrated that two zero dispersion wavelengths can be achieved in optical communication band between 0.8μm and 1.7μm, and the first zero-dispersion wavelength is in the working wave band of Ti: Sapphire oscillator, which contributes to frequency conversion of Ti: Sapphire femtosecond laser. PCF with two zero-dispersion wavelengths can make strong power supercontinuum spectral in near infrared band.Moreover, Mid-infrared transmissive chalcogenide glass hollow-core bandgap fiber structures are theoretically modeled. The bandgap of these fibers are analyzed using the plane wave expansion method; the waveguide group velocity dispersion and confinement loss of gallium lanthanum suphide glass properties are investigated by employing the multipole method. In particular, the structures have several wide and closely spaced bandgaps at air-filling of 75% to 85% that have potential for mid-infrared transmission. Moreover, the analysis of waveguide GVD and confinement loss properties of GLS glass HC-PCF provide evidence for applications.Finally, A highly birefringent hollow-core photonic bandgap fiber, which has a big elliptical center air hole and can guide communicational wavelength 1.55μm, is proposed. It is shown from computed results by a full vector plane wave expansion method that the proposed photonic bandgap fiber has birefringence 6.07×10^-3and 1.06×10^-3 at 1550 nm.