Opt Lett. 2019 Apr 1;44(7):1564-1567. doi: 10.1364/OL.44.001564.
We report ultrafast laser inscription of nanogratings possessing form birefringence in binary sodium germanate glasses in a wide range of NaO content from 3 to 22 mol.%. A minimal number of laser pulses required to induce noticeable form birefringence is shown to grow exponentially with NaO content in glass. Atomic force microscopy showed similarity of their periodical structure and period value to those in the nanogratings formed in fused silica. A sharp pulse duration threshold below which laser pulses do not induce nanogratings in the studied glasses has been revealed. Formation of a nanograting in 22NaO·78GeO at the studied conditions is accompanied by crystallization of a surrounding submicron layer and partial crystallization inside the nanograting with precipitation of NaGeO crystals.
我们报告了在从 3 到 22 mol%的宽范围内的二元锗酸钠玻璃中，具有形式双折射的纳米光栅的超快激光刻写。诱导明显形式双折射所需的激光脉冲数被证明随玻璃中 NaO 含量呈指数增长。原子力显微镜显示其周期性结构和周期值与在熔融石英中形成的纳米光栅相似。在研究的玻璃中，揭示了一个尖锐的脉冲持续时间阈值，低于该阈值激光脉冲不会诱导纳米光栅的形成。在研究条件下，在 22NaO·78GeO 中形成纳米光栅伴随着周围亚微米层的结晶和纳米光栅内部的部分结晶，析出 NaGeO 晶体。
