Abstract A carefully controlled femtosecond laser irradiation offers the possibility of fabricating high quality, 3D functional single-crystal patterns designed for integrated optical devices deep inside glass. Notwithstanding, a general theory relating particular irradiation conditions to crystal growth dynamics and resulting morphologies remains to be established. To overcome this challenge, crystal lines written in glass under varying conditions are investigated in this work by optical microscopy, scanning electron microscopy, and electron backscatter diffraction in the congruently crystallizing LaBGeO5 model system. We show that despite a strongly preferential orientation of the optic axis along the direction of laser scanning, typical morphologies of fs laser-written crystals in this system are inhomogeneous due to low-angle grain boundaries and rotations or inversions of the preferential axis. Nevertheless, uniform single crystals can be produced under optimized irradiation conditions. The theoretical dynamics of crystal growth is developed within the unique environment of a moving laser-induced melt to explain these results, including the role of competitive growth in establishing the preferential lattice orientation; the effects of temperature gradient and focal scan rate in establishing crystal morphology and cross-section shape; and most notably, the specific design criteria that must be met for stable single-crystal growth.

中文翻译：

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玻璃中 3D 晶体结构的飞秒激光写入：生长动力学和形态控制

摘要 精心控制的飞秒激光照射为制造专为玻璃内部集成光学器件设计的高质量 3D 功能单晶图案提供了可能性。尽管如此，将特定辐射条件与晶体生长动力学和所得形态相关联的一般理论仍有待建立。为了克服这一挑战，在这项工作中，通过光学显微镜、扫描电子显微镜和电子背散射衍射研究了在不同条件下写在玻璃上的结晶线，在全等结晶的 LaBGeO5 模型系统中。我们表明，尽管光轴沿激光扫描方向具有强烈的优先取向，由于小角度晶界和优先轴的旋转或反转，该系统中 fs 激光写入晶体的典型形态是不均匀的。然而，在优化的辐照条件下可以生产均匀的单晶。晶体生长的理论动力学是在激光诱导熔体移动的独特环境中发展起来的，以解释这些结果，包括竞争性生长在建立优先晶格取向中的作用；温度梯度和焦点扫描速率对建立晶体形态和横截面形状的影响；最值得注意的是，稳定单晶生长必须满足的特定设计标准。在优化的辐照条件下可以生产均匀的单晶。晶体生长的理论动力学是在激光诱导熔体移动的独特环境中发展起来的，以解释这些结果，包括竞争性生长在建立优先晶格取向中的作用；温度梯度和焦点扫描速率对建立晶体形态和横截面形状的影响；最值得注意的是，稳定单晶生长必须满足的特定设计标准。在优化的辐照条件下可以生产均匀的单晶。晶体生长的理论动力学是在激光诱导熔体移动的独特环境中发展起来的，以解释这些结果，包括竞争性生长在建立优先晶格取向中的作用；温度梯度和焦点扫描速率对建立晶体形态和横截面形状的影响；最值得注意的是，稳定单晶生长必须满足的特定设计标准。温度梯度和焦点扫描速率对建立晶体形态和横截面形状的影响；最值得注意的是，稳定单晶生长必须满足的特定设计标准。温度梯度和焦点扫描速率对建立晶体形态和横截面形状的影响；最值得注意的是，稳定单晶生长必须满足的特定设计标准。