Nonlinear Change in Refractive Index and Transmission Coefficient of ZnSe:Fe<sup>2+</sup>at Long-Pulse 2.94-μm Excitation

• 作者: Alexander S. Nasibov Alexander V. Kir’yanov Elmira S. Gulyamova Nikolai N. Il’ichev Peter V. Shapkin
• 来源期刊: 光学与光子学期刊(英文)
• 学科: 医学
• 关键词: NONLINEAR Refractive index NONLINEAR Transmission Z-SCAN Technique Thermal lens ZnSe:Fe2+
• 年，卷（期）: 2015,（1）
• 页码范围: 15-27
• 页数: 13页
• 分类号: R73

摘要

An experimental study of the nonlinear changes in refractive index and transmission coefficient of single-crystal ZnSe:Fe2+, fabricated through the Fe-diffusion method, at long-pulse (~300 ns), sub-mJ, 2.94-mm Z-scan probing is reported. As well, a theoretical model based on the generalized Avizonis-Grotbeck equations is developed and applied for straightforward fitting of the open- and closed-aperture Z-scans, obtained for ZnSe:Fe2+ with different Fe2+ centers concentrations. The modeling results reveal that the contributions in the absorption and refractive index nonlinearities of ZnSe:Fe2+ are “common” resonant-absorption saturation (the minor part) and pulse-induced heating of the samples (the major part), which are strongly dependent on Fe2+ concentrations. Large values of the index change (>~10-3) and partial resonant-absorption bleaching (limited by ~50%), both produced via the thermal effect mainly, are the features of the ZnSe:Fe2+ samples inherent to this type of excitation.