【摘要】 提出了一种精确评估光学薄膜损伤阈值的方法。放大的自发辐射(ASE)光源由于时间相干性和空间相干性较差,所以在近场区域光场强度分布均匀,聚焦后远场也没有被非均匀调制。采用ASE光束作为光学元件损伤阈值测试的辐照光源,可以提高辐照光源的均匀度,实现对光学薄膜损伤阈值的精确评估。ASE光源由神光II高功率激光装置的一级钕玻璃棒状放大器输出,脉宽经过光电开关调制后为9ns,能量输出在几毫焦耳到几十焦耳范围内可调节,光谱半峰全宽(FWHM)为1nm。根据标准ISO-11254,实验获得ASE测试TiO2高反膜的损伤阈值为15.1J/cm2,高于激光测试样品的损伤阈值7.4J/cm2(脉宽为9ns时),更准确地评估了样品的损伤阈值。更多还原

【Abstract】 A method to accurately evaluate optical thin-film damage threshold is presented.The poor coherences in time and space of amplified spontaneous emission(ASE)result in a very smooth beam profile in the near-field region and uniform intensity distribution of the focused beamlet in the far-field region.In order to increase the uniformity of the irradiation source and test the damage threshold with a greater precision,ASE beam is used to test the damage threshold.ASE is generated by a rod amplifier of the Nd…glass in SG-II high power laser system.The pulse duration is 9 ns after an electro-optical switch with the output energy changing from a few millijoules to tens of joules.The spectral full width at half maximum(FWHM)is 1 nm.According to ISO-11254,the damage threshold of the TiO2 high reflection film using ASE is 15.1 J/cm2,which is higher than that of 7.4 J/cm2 tested by laser with pulse duration of 9 ns.So a more accurate evaluation of the samples damage thresholds can be obtained using ASE as the irradiation source.更多还原