设计了一种高双折射高非线性光子晶体光纤,采用全矢量有限元法研究了这种光纤的基模模场、双折射、非线性、有效模面积及色散特性。数值研究发现,减小孔间距Λ的大小,在波长1550 nm处,该光纤可获得10−2数量级的双折射B,比普通的椭圆保偏光纤高约两个数量级；同时,该光纤可获得42 W−1·km−1的高非线性系数γ。另外,分别在可见光和近红外波段出现了两个零色散波长,在波长800—2000 nm之间具有良好的色散平坦特性。这种设计为获得高双折射高非线性超平坦色散光子晶体光纤提供了一种新的方法,该光纤在偏振控制、非线性光学和色散控制方面具有广泛的应用前景。%A kind of highly birefringent and highly nonlinear photonic crystal fiber (PCF) is proposed. The fundamental mode field, birefrin-gence, nonlinear coefficient, effective mode area and dispersion characteristic of the fiber are studied by the full-vector finite element method. Simulation results show that the birefringence becomes larger by reducing the air hole pitch, and the birefringence reaches up to 10−2 at a wavelength of 1550 nm, which is about two orders of magnitude higher than that of the regular elliptic polarization maintaining fiber. At the same time, a nonlinear coefficient of 42 W−1 ·km−1 is obtained. There are two zero dispersion wavelengths in the visible and the near-infrared region respectively, and flattened chromatic dispersion from 800 nm to 2000 nm is obtained. Such a design provides a new approach to obtaining highly birefringent and highly nonlinear PCF, and the fiber has a broad prospect of application in the polarization control, nonlinear optics and dispersion control.
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