Study of linear optical properties and two-photons absorption in Zn1-xMgxSe thin layers

Reflection spectroscopy is used to obtain the refractive index of Zn1-xMgxS e layers for the series of alloy composition x, at energies below the energ y gap of these semiconductors. It is shown that the linear refractive indic es decrease with Mg content. The two-photon absorption coefficient (beta) w as obtained from the nonlinear transmission. A relatively strong nonlinear absorption, which increases with an increase of Mg composition, is observed . Maximal value of the TPA coefficient is obtained for the Mg content about 40%. The technological figure of merit parameter Im(chi ([3]))/alpha shows evident maximum for Mg content at 7%. (C) 2000 Elsevier Science B.V. All r ights reserved.