Eur. Phys. J. B 84, 241–247 (2011) DOI: 10.1140/epjb/e2011-20470-9 Regular Article T HE EUROPEAN P HYSICAL JOURNAL B Linear and nonlinear optical absorption coefficients in inverse parabolic quantum wells under static external electric field S. Baskoutas 1, a , C. Garoufalis 1,3 , and A.F. Terzis 2 1 Department of Materials Science, School of Natural Sciences, University of Patras, Rion, 26504, Greece 2 Department of Physics, School of Natural Sciences, University of Patras, Rion, 26504, Greece 3 Department of Environment Technology & Ecology, Technological Institute of Ionian Islands, 2 Kalvou Sq, 29100, Zakynthos, Greece Received 15 June 2011 / Received in final form 21 September 2011 Published online 10 November 2011 – c  EDP Sciences, Societ`a Italiana di Fisica, Springer-Verlag 2011 Abstract. In the present theoretical study, the linear and third-order nonlinear optical absorption coef- ficients have been calculated in GaAs/Ga1-x AlxAs inverse parabolic quantum wells (single and double) subjected to an external electric field. Our calculations are based on the potential morphing method in the effective mass approximation. The systematic theoretical investigation contains results with all possible combinations of the involved parameters, as quantum well width, quantum barrier width, Al concentration at each well center and magnitude of the external electric field. Our results indicate that in most cases investigated, the increase of the electric field blue-shifts the peak positions of the total absorption coeffi- cient. In all cases studied it became apparent that the incident optical intensity considerably affects the total absorption coefficient. 1 Introduction Several investigations, experimental and theoretical have been devoted to two dimensional hetero-structures pro- duced by ultrathin-film growth in one direction (i.e. growth by one layer after the other) known as quantum wells [1–3]. Due to their small size these structures present physical properties that are quite different from those of the bulk semiconductor constituents [2–5]. In addi- tion the recent advances in nanofabrication technology, it has become possible to produce high-quality semiconduc- tor quantum wells with desired shape of the confinement potential. Apart from the well-known and well-studied quantum well hetero-structures (QWHs), which have square [3,6] and parabolic [3,7–10] potential shape, cases of QWHs with half parabolic [11], graded [12], V-shaped [13] and inverse parabolic quantum well (IPQW) potential shape [14–20] have been produced and studied. As the IPQW gives the possibility to realize high- performance optoelectronic devices the existing litera- ture on its fundamental physical properties has increased lately [14–24]. Especially, the nonlinear optical properties such as optical absorption [25–27] have the potential for device applications in far-infrared laser amplifiers [28] pho- todetectors [29] and high speed electro-optical modula- tors [30]. Therefore, for both fundamental and applied re- searches, the nonlinear optical properties of semiconductor a e-mail: bask@upatras.gr quantum wells have attracted much attention in recent years [31]. Furthermore, it is well known that the nonlinear op- tical properties of semiconductor QW mainly depend on the asymmetry of the confining potential. Such an asym- metry in potential profile can be obtained, for example, either by applying an electric field to a symmetric QW or by compositionally grading the QW. Therefore, sev- eral studies were pointed out on the theoretical analysis of linear and third order nonlinear optical absorption in asymmetric QW [26,32]. Also, the electric field effects on these properties are examined. In the present paper, the case of inverse parabolic quantum wells (single and double IPQW) subjected to an external perpendicular electric field is considered. We will attempt to study the influence of electric field, structural data and optical intensity on the linear and third-order nonlinear optical absorption coefficients. The calculation method we are using is the potential morphing method (PMM) [33] which has already been applied in the past for the study of optical properties of several nanostruc- tures [34–40]. Our work is organized and presented in four chapters. Next chapter is devoted to the presentation of our theo- retical model. Then, in chapter 3 we present our numerical results and attempt explanation of the observed behavior. In the last chapter, we conclude our article by summa- rizing our results and pointing out the most important findings.