Farahani Shahrzad Shahrabi, Madanipour Khosro, Koohian Ata
Appl Opt. 2017 May 1;56(13):3634-3638. doi: 10.1364/AO.56.003634.
In this work, a nonscanning measurement technique is presented for determining the nonlinear refractive index and absorption coefficient of liquid media based on Moiré deflectometry. In the proposed method two lasers are used: a low power, wide beam as probe and a high power with specific wavelength as a pump. Interaction of the pump laser beam with the nonlinear sample changes the refractive index, which leads to change in convergence/divergence of the collimated incident probe laser beam. The induced deflection is monitored by Moiré deflectometry. If the pump laser has a Gaussian intensity profile, the refractive index profile of the sample is Gaussian, too. Measuring the deflection angle of the probe beam by Moiré fringes deflection, and by using the inverse Abel transform integral, the refractive index profile and nonlinear refractive index can be determined. This method is fast, easy, and insensitive to environmental noise and allows real-time measurement. Also, the refractive index profile of the interacted medium with pump laser can be achieved by this technique. As a liquid sample, a DCJ dye in water solution was studied. The value of nonlinear refractive index, n, and absorption coefficient, α, were obtained -2.54×10 cm w and 1.368 cm, respectively.
在这项工作中，提出了一种基于莫尔偏转术测定液体介质非线性折射率和吸收系数的非扫描测量技术。在所提出的方法中使用了两台激光器：一台低功率、宽光束的激光器作为探测光，另一台具有特定波长的高功率激光器作为泵浦光。泵浦激光束与非线性样品的相互作用会改变折射率，这会导致准直入射探测激光束的会聚/发散发生变化。通过莫尔偏转术监测诱导偏转。如果泵浦激光具有高斯强度分布，样品的折射率分布也是高斯分布。通过莫尔条纹偏转测量探测光束的偏转角，并使用逆阿贝尔变换积分，可以确定折射率分布和非线性折射率。该方法快速、简便，对环境噪声不敏感，可进行实时测量。此外，通过该技术还可以获得与泵浦激光相互作用的介质的折射率分布。作为液体样品，研究了水溶液中的DCJ染料。获得的非线性折射率n和吸收系数α的值分别为-2.54×10⁻¹² cm²/W和1.368 cm⁻¹。
