中文摘要：

为得到纯石英阶跃光纤（SI-PDF）中漏泄模式光线功率的传输特性,应用光线投影积分法,推导了不同入射角的激光束在大芯径SI-PDF光纤中的传输功率计算公式,在不同入射角激光束照射下,分别对3、671、40 m SI-PDF光纤的输出功率特性进行了理论和实验研究,用最小二乘法原理对对数坐标下的实验数据进行拟合,得出了损耗系数。结果表明：入射角在0~12°内时,不同入射角功率输出和损耗系数近似一常量,其中损耗系数约为13 dB/km;入射角＆gt;12°时,不同入射角光功率随入射角增加呈指数衰减规律,其损耗系数随入射角增大而增大,在12°时损耗系数值为26 dB/km,在28°时达到了82 dB/km。

英文摘要：

In order to obtain transmission property of tunneling rays in a short length large-core SI- PDF fiber, a formula is derived by a light-ray projection integral method to calculate the power cou- pled from laser beam with different incident angles in the SI-PDF fiber. The output power characteris- tics of laser beams of 3,67,140 m length fibers at different incident angles are achieved respectively by measurements and theoretic calculations. The loss coefficiens are obtained by the least square fitting to experimental data at a logarithm coordinate. Results show that the coupled power and the loss coef- ficients with different incident angles in the SI-PDF fiber keep almost a constant at 0°-12°,and the coupled power goes down exponentially with different incident angles beyond 12°. Moreover, the loss coefficients increase with increase of incident angles,it is 26 dB/km at 12° and 82 dB/km at 28°.