Novel polarization phenomena and their spectroscopic application in bulk solids and films
Novel polarization phenomena and their spectroscopic application in bulk solids and films
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新颖的偏振现象及其在散装固体和薄膜中的光谱应用
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发表时间：
1998
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通讯作者：
P. Bennett
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作者：
P. Bennett
研制了一种先进的飞秒激光微偏振计，用于测量不透明和半透明样品的瞬态泵浦探针偏振。该偏振计已用于飞秒Kerr锁模Ti：蓝宝石（810nm）和Cr:forsterite （1260nm）激光器，并在反射和透射配置。在反射配置下，Ti：蓝宝石激光器实现了32fs的时间分辨率，Cr:forsterite激光器实现了90fs的时间分辨率。在这两种情况下，极化方位旋转的分辨率都优于10^-6弧度。为了研究强自然极化旋转背景下的非互易极化现象，研制了一种基于偏振调制技术的双通偏振计。在波长514.5、501.7、496.5、476.5和457.9 nm的氩离子激光器中，对非倒易极化旋转的灵敏度优于5 × 10^-4弧度。利用泵浦-探针镜面反法拉第效应，首次在1260nm和810 nm波长处测量了块体金的简并立方光学非线性。在1260 nm处，在金中观察到泵浦功率的反射探针偏振方位角旋转为~1 × 10^-14 rad cm^2/W，这对应于相当大的非线性：| ~ 10^-9 esu（高斯），10^-16 m2伏特^-2 （SI）。非线性响应在810nm处快于40fs，在1260nm处快于90fs。非线性主要归因于自旋翻转机制。本文首次在~3 ~ 30nm厚度的不透明和半透明镍薄膜中，在810nm波长处测量了频率退化非线性光学响应。在镍膜的空气和玻璃界面处，同时测量了反射和透射配置下泵浦诱导偏振方位旋转，表明了表面在决定非线性响应中的重要性。研究结果表明，在4 ~ 5nm深度处，表层对非线性有显著影响。由于克尔效应，非线性偏振旋转出现在背景上，但与线性偏振旋转无关。从观察到的大镜面反法拉第效应来看，镍薄膜已被证明适合用于宽带飞秒自相关脉冲持续时间的测量。在光纤全光开关中，液化镓的非线性特性已被用于光调制，在毫瓦的工作功率水平上实现宽带光，其频带可达几百千赫兹。首次在光学活性晶体Bi12SiO20中发现了自然极化旋转的非互易性。在常规旋光性的偏振旋光背景下，观测到~2 × 10^-3弧度的偏振旋光非倒数分量。非互反旋转归因于非局域张量Re{gamma xyz + gamma xyz}的对称部分的存在~ 5 x 10^-12 cm（高斯），6 x 10^-9m (SI)，在457.9nm处[注意“w”代表l.c. ω]
An advanced femtosecond laser micropolarimeter has been developed for transient pump-probe polarization measurements in opaque and semitransparent samples. The polarimeter has been used with femtoecond Kerr modelocked Ti:sapphire (810nm) and Cr:forsterite (1260nm) lasers, and in both reflective and transmissive configurations. A time resolution of 32fs was achieved with the Ti:sapphire laser, in a reflective configuration, and a time resolution of 90fs was achieved with the Cr:forsterite laser. In both cases a resolution to polarization azimuth rotation better than 10^-6 radians was achieved. A double pass polarimeter, based on a polarization modulation technique, has been developed for the study of nonreciprocal polarization occurring on the background of strong natural polarization rotation. A sensitivity to nonreciprocal polarization rotation better than 5 x 10^-4 radians has been achieved at several wavelengths of an argon ion laser: 514.5, 501.7, 496.5, 476.5 and 457.9 nm. The degenerate cubic optical nonlinearity in bulk gold was measured for the first time, at wavelengths of 1260nm and 810 nm, using a technique based on the pump-probe specular inverse Faraday effect. A reflected probe polarization azimuth rotation of ~1 x 10^-14 rad cm^2/W of pump power was seen in gold at 1260 nm, this corresponds to a considerable nonlinearity of |chi xxyy(3)(w,w,w,-w) - chi xyyx(3)(w,w,w,-w)| ~ 10^-9 esu (gaussian), 10^-16 m2 Volt^-2 (SI). The nonlinear response was found to be faster than 40fs at 810nm, and faster than 90fs at 1260nm. The nonlinearity is attributed predominantly to a spin-flipping mechanism. The frequency degenerate nonlinear optical response has been measured for the first time in opaque and semitransparent nickel films, of ~3-30nm thickness, at a wavelength of 810nm. Simultaneous measurements of the pump induced polarization azimuth rotation in reflective and transmissive configurations, at both the air and glass interfaces of the nickel films, indicated the importance of the surface in determining the nonlinear response. It has been established that the surface layer significantly influences the nonlinearity to a depth of about 4-5nm into the bulk. The nonlinear polarization rotation appears on the background, but is independent of, the linear polarization rotation due to the Kerr effect. From the large specular inverse Faraday effect observed, nickel films have been shown to be suitable for use in broadband femtosecond autocorrelation pulse duration measurements. A nonlinearity of liquefying gallium has been used to achieve broadband light by light modulation, at milliwatt operating power levels, with a frequency band spanning up to several hundred kilohertz, in a fibrized all-optical switch. For the first time nonreciprocity of natural polarization rotation has been seen in the optically active crystal, Bi12SiO20. A nonreciprocal component of the polarization rotation of ~2 x 10^-3 radians was observed on the background of the polarization rotation due to conventional optical activity. The nonreciprocal rotation has been attributed to the presence of the symmetric part of the nonlocality tensor Re{gamma xyz + gamma xyz} ~ 5 x 10^-12 cm (gaussian), 6 x 10^-9m (SI), at 457.9nm. [note that "w" represents l.c. omega]