Determination of the mid-IR femtosecond surface-damage threshold of germanium
Determination of the mid-IR femtosecond surface-damage threshold of germanium
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DOI：
10.1007/s00339-012-7499-9
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发表时间：
2013-10-01
影响因子：
2.7
通讯作者：
Rutt, Harvey N.
中科院分区：
文献类型：
--
作者：
Malik, Rohit;Mills, Ben;Rutt, Harvey N.
为了评估锗作为中红外非线性材料的潜在用途，我们使用波长为 3.9 μm 的飞秒脉冲测量了锗光学窗口的表面损伤阈值。通过使用与小于带隙能量一半的光子能量相对应的波长，消除了由于一光子和二光子吸收而产生的自由载流子。激光脉冲的能量为 5.5 μJ，持续时间为 255 fs，并聚焦到腰部尺寸约为 100 μm。锗窗的多次损伤阈值估计约为 94 GW/cm(2)。这些数据应该能让在中红外区域工作的工业激光研究人员和应用工程师立即受益。
To assess the potential uses of germanium as a nonlinear material in the mid IR we have measured the surface-damage threshold of germanium optical windows using femtosecond pulses at a wavelength of 3.9 mu m. By working with a wavelength corresponding to a photon energy of less than half the band-gap energy, free-carrier generation due to one- and two-photon absorption was eliminated. The laser pulses had an energy of 5.5 mu J, a duration of 255 fs, and were focused to a waist size of approximately 100 mu m. The multi-shot damage threshold of the germanium windows was estimated to be approximately 94 GW/cm(2). The data should be of immediate benefit to industrial laser researchers and applications engineers working in the mid-IR region.