中文摘要：

利用角锥棱镜将准直飞秒高斯光束转变为飞秒贝塞尔光束,利用飞秒贝塞尔光束在石英玻璃样品中刻写了单芯和双芯光波导.实验中首先使用无像散的脉宽50 fs的贝塞尔激光脉冲在石英玻璃中刻写出单芯光波导,研究了波导直径和折射率改变量随激光脉冲能量和脉冲个数的变化关系.通过旋转角锥棱镜,在飞秒贝塞尔光束中引入像散,利用像散飞秒贝塞尔光束在石英玻璃中刻写了双芯光波导.实验发现,当角锥棱镜的转角为1？时,可以制备出双芯间距仅为5.6μm的双芯光波导.当双芯波导沿某一方向移动时,在近场可观察到从双芯输出的光强出现周期性的亮暗变化,这应是由双芯间距较小导致的.当角锥棱镜的转角增大至3？和5？时,制备的波导双芯之间的间距分别增大至9.1μm和16.1μm,此时没有观察到双芯光强随位置改变的往复变化.本文刻写的双芯光波导可用作高灵敏度差分位移传感器（可探测的最小位移小于3μm）.与传统的单芯波导的位移传感器相比,双芯波导差分位移传感器一方面大幅提高了探测的灵敏度和信噪比;另一方面也降低了高灵敏度位移传感器的装配难度.

英文摘要：

In this paper, a collimated femtosecond Gaussian beam with a central wavelength of 800 nm and a pulse duration of 50 fs is converted into a Bessel beam by an axicon with an apex angle of 140？. By adjusting the femtosecond Gaussian beam incidence angle on the axicon, both anastigmatic and astigmatic femtosecond Bessel beams can be generated. Single- and double-core optical waveguides are fabricated in silica glass respectively by using anastigmatic and astigmatic femtosecond Bessel beams. Anastigmatic femtosecond Bessel beams with different single pulse energies（0.39 m J and 0.47 m J） are employed to fabricate the single-core optical waveguides in silica glass. The fabricated singlecore waveguide＇s core diameter and refraction index change are found to be dependent on both the single pulse energy and pulse number used to fabricate the waveguide. By rotating the axicon, femtosecond Bessel beam with astigmatism is generated, which is used to fabricate double-core optical waveguides in silica glass. In the experiments 50 fs laser pulses with single pulse energy of 0.36 m J are employed to fabricate the double-core optical waveguide. Experimental results show that when the rotation angle of the axicon is relatively small（1？）, i.e., the incidence angle of the femtosecond Gaussian beam on the axicon is 89？, the distance between the two cores of the fabricated double-core waveguide is only 5.6 μm. In this case the energy ratio of the coupled He-Ne laser between the two cores varies periodically as the waveguide＇s position changes towards one specific direction. When the axicon is rotated 3？and 5？, the distances between the two cores increase respectively up to 9.1 μm and 16.1 μm, and no periodic variation of the coupled light energy ratio between the two cores is observed. It is inferred that the waveguides fabricated using the axicon with rotation angles of3？and 5？are in fact optical waveguides with double parallel cores. According to the experimental results shown above,it is deduced that t