飞秒激光在掺Yb^(3+)磷酸盐玻璃中刻写双线型光波导的研究

Study on Writing Double Line Waveguide in Yb^(3+)∶Phosphate Glass by Femtosecond Laser

利用重复频率为50 k Hz,中心波长为790 nm,脉冲宽度为140 fs的飞秒激光脉冲在掺Yb3+磷酸盐玻璃中刻写双线型光波导。研究了双线间距,激光脉冲能量和刻写速度对波导形成的影响,并测试了不同刻写参数下波导的导光模式。实验结果表明,在双线间距为35μm,激光脉冲能量为1.0μJ,刻写速度为600μm/s的条件下写入的光波导导光性能最优;利用近场模式重建了激光诱导该波导的折射率二维分布,波导区域相对于基质的最大折射率改变为1.5×10-4,并利用散射法测试了波导的传输损耗,传输损耗为1.56 d B/cm。发现了波导具有偏振导光现象,偏振态平行于双线方向的激光可以导通,偏振态垂直于双线方向的激光不能导通。

By using femtosecond laser with repetition frequency of 50 kHz, center wavelength of 790 nm, and pulse width of 140 fs, double line waveguides are inscribed in Yb3~ doped phosphate glass. The influences of double-line separation, laser pulse energy and writing speed on the waveguide formation are investigated and the near-field modes of waveguides written by different laser parameters are measured. The experimental results show that the waveguide has good property of guiding under the writing conditions of double-line separation of 35μm, pulse energy of 1.0μJ and scanning speed of 600 μm/s. By using near-field mode, bivariate distribution of the waveguide refractive index is reconstructed with the maximum refractive index change of 1.5 × 10- 4. The propagation loss of the waveguide is 1.56 dB/cm by testing with the scattering technique. The phenomenon of polarization guiding is discovered from the waveguide. The waveguide can guide the laser with polarization parallel to the direction of double line and the laser with polarization perpendicular to the direction of double line cannot be guided.