Research On The Dispersion And Bandgap Properties Of New Photonic Crystal Fibres

With the development of information society, optical fiber communication network is evolving towards high speed and large capacity and the practical application proposed higher and higher request to the fiber performance. The characteristics of dispersion and photonic band-gap are two important fields investigated in Photonic Crystal Fiber (PCF). Besides, Yb3+-doped laser glass is an indispensable medium of high-power laser. With the birth of photonic crystal fiber, people start trying to make combination of Yb3+-doped glass medium with photonic crystal fibers because of its superior optical properties, which will be the ideal medium for the preparation of ultra-high-power lasers.The dispersion characteristic of a new Double-Cladding Hybrid Photonic Crystal Fiber (DC-HyPCF) and photonic band-gap characteristic of Yb3+-doped Photonic Band-Gap Photonic Crystal Fiber (PBG-PCF) are investigated respectively in this paper. Moreover, Yb3+-doped glass is prepared by high-temperature crucible melting method and it can realize the requirement of the Yb3+-doped photonic crystal fiber through theoretical and experimental study. The main results are summarized as follows:Firstly, based on multi-pole method, a kind of hybrid cladding photonic crystal fiber is put forward. It has been shown theoretically that it is possible to obtain ?attened dispersion within the wave band of 1.44μm to 2.0μm by altering four structure parameters of the five-ring hybrid cladding PCF (the diameter of the inner ring holes, the diameter of the outer four rings holes, the pitch of the hexagon and the pitch of the octagon), and the absolute value of dispersion coefficient merely changes 1.25 ps/km/nm. Moreover, simulation results show that this PCF can assume low confinement losses of 0.005 dB/km in a 1.44~2.0μm wavelength range. Secondly, a series of Yb3+-doped silicate laser glass were prepared by high-temperature crucible melting method, the fluorescence spectra parameters such as spectral properties were tested. The impact of rare earth ions doping concentration and glass composition changes on the glass spectrum were analyzed, the optimum doping concentration was obtained under the conditions of this experiment.Finally, Yb3+-doped Photonic Band-Gap Photonic Crystal Fiber designed by myself is simulated by Plane Wave Method (PWM). Furthermore, the influence of structure parameters, for example, the diameter, pitch and fill percent of Yb3+-doped Photonic Band-Gap Photonic Crystal Fiber on the band-gap position and properties has been discussed.