G.M. Mamedov

The effect of thickness and/or doping on the nonlinear and saturable absorption behaviors in amorphous GaSe thin films

We investigated the nonlinear and saturable absorption characteristics of very thin amorphous undoped GaSe, Ge (0.01 at. %), and Sn (0.5 at. %) doped GaSe films by pump-probe and open aperture Z-scan techniques. Linear absorption measurements indicate blueshift in energy with increasing film thickness. Thinner films exhibit saturable absorption while thicker films exhibit nonlinear absorption for 4 ns and 65 ps pulse durations. The films exhibit competing effects between nonlinear and saturable absorption. Saturable absorption behavior weakens while nonlinear absorption appears with increasing film thickness. In addition to that, saturable absorption behavior is very sensitive to doping. Doping causes absorption behaviors to appear in thinner films compared to undoped films. These behaviors are attributed to increasing localized defect states with increasing film thickness and doping. To derive the transmission in open aperture Z-scan data, a theoretical model incorporating one photon, two photon, and fre...

The effect of thickness and doping on the nonlinear absorption behaviour of IIIA-VIA group amorphous semiconductor thin films

The nonlinear optical absorption of InSe, GaSe and GaxIn1−xSe amorphous films with varying thickness and doping has been studied by open-aperture Z-scan experiment with 4 ns and 65 ps pulse durations at 1064 nm wavelength and femtosecond pump-probe spectroscopy. Our results show that the dopant and film thickness (from 20 nm to 104 nm) results in switching from saturable absorption to nonlinear absorption for equal input intensities. This behaviour is attributed to increasing localized defect states with increasing film thickness and/or dopant. The experimental curves were fitted to the theory of open aperture Gaussian beam Z-scan based on the Adomian decomposition method incorporating one photon, two photon, and free carrier absorptions and their saturations. By preparing very thin amorphous thin films the saturation threshold has been lowered significantly.

Switching from negative to positive nonlinear absorption in Sn-doped GaSe crystal

25th European Crystallographic Meeting, ECM 25, İstanbul, 2009 Acta Cryst. (2009). A65, s 213 Page s 213 FA2-MS07-P01 Switching from Negative to Positive Nonlinear Absorption in Sn Doped GaSe Crystal. Ayhan Elmalia, Mustafa Yükseka, Mevlüt Karabulutb, G. M. Mamedovb. aDepartment of Engineering Physics, Faculty of Engineering, Ankara University, 06100 Beşevler, Ankara, Turkey. bDepartment of Physics, Kafkas University, 36100 Kars, Turkey. E-mail: elmali@eng.ankara.edu.tr