Diffraction gratings written inside/on lithium niobate by means of femtosecond laser pulses
Diffraction gratings written inside/on lithium niobate by means of femtosecond laser pulses
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DOI：
10.1117/12.673307
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发表时间：
2006-04
期刊：
影响因子：
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通讯作者：
G. Torchia;C. Méndez;D. Delgado;J. R. A. Vázquez;I. Arias;L. Roso
中科院分区：
文献类型：
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作者：
G. Torchia;C. Méndez;D. Delgado;J. R. A. Vázquez;I. Arias;L. Roso
本文研究了利用聚焦飞秒激光脉冲在铌酸锂衬底上制作衍射栅的工艺。文中介绍了这些光子结构的主要光学特性。正如预期的那样，浮雕光栅表现出与晶体-空气边界的折射率调制轮廓相一致的高衍射效率，从而产生了这种衍射结构。另一方面，对于内栅，一阶衍射效率较高，但总的衍射效率与本文制作的烧蚀结构相似，这一结果表明内槽的折射率增量应该是非常重要的。本文还对这些结构的热稳定性进行了研究和讨论。结果表明，浮雕光栅的衍射效率在400℃以下与温度无关，而内栅在400℃热处理2小时后，其衍射效率略有下降。本文提出的光栅化制作方法可以为利用飞秒激光一步法在Nb酸锂晶体内/衬底上制作多种光子器件提供有力的工具。
This work deals on the fabrication process of diffraction gratings made on Lithium Niobate substrates by means of focusing femtosecond laser pulses. The main optical features of these photonic structures are presented in this paper. As it was expected the relief gratings showed high diffraction efficiency in accordance to the index modulated profile of the crystal-air border resulting in this kind of diffractive structure. On the other hand, for the inside grating a higher diffraction efficiency for the first orders were found, however the overall diffraction efficiency was found to be similar to that obtained for the ablation structures made in this work; this result suggests that the index increment in the inside grooves should be very important. The thermal stability of these structures is also studied and discussed in this paper. It is found that for the relief gratings the diffraction efficiency is temperature independent up to 400°C degrees, while for the inside gratings a slight decrease on diffraction efficiency was observed after making a thermal annealing at 400°C during two hours. The grating fabrication method presented in this work can be a powerful tool for development of several photonic devices made inside/on Lithium Niobate by using femtosecond laser writing by means of the one step process.