Author(s)

Alexander V. Kir’yanov^1,2*, Nikolai N. Il’ichev³, Elmira S. Gulyamova³, Alexander S. Nasibov⁴, Peter V. Shapkin⁴

¹Centro de Investigaciones en Optica, Loma del Bosque 115, Lomas del Campestre, Leon, Mexico.
²M.V. Lomonosov Moscow State University, Physics Department, Vorobyevy Gory, 1, Moscow, Russia.
³A.M. Prokhorov General Physics Institute (Russ. Acad. Sci.), Ul. Vavilova 38, Moscow, Russia.
⁴P.N. Lebedev Physical Institute (Russ. Acad. Sci.), Ul. Vavilova 38, Moscow, Russia.

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.

Nonlinear Refractive index, Nonlinear Transmission, Z-Scan Technique, Thermal lens, ZnSe:Fe²⁺

Kir’yanov, A. , Il’ichev, N. , Gulyamova, E. , Nasibov, A. and Shapkin, P. (2015) Nonlinear Change in Refractive Index and Transmission Coefficient of ZnSe:Fe²⁺ at Long-Pulse 2.94-μm Excitation. Optics and Photonics Journal, 5, 15-27. doi: 10.4236/opj.2015.51003.