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We have performed a theoretical calculation of the two photon absorption (TPA) in semiconducting quantum wires and quantum boxes in the presence of an electric field. Because of the anisotropic nature of these nanostructures, the TPA depends on the relative orientations of the electric field, the direction of polarization of the optical field, and the direction of carrier confinement in these semiconducting nanostructures. Numerical results show that the electric field decreases the TPA in quantum wires and boxes for any direction of the electric field and optical polarization. The TPA occurs below the zero field threshold energy of the semiconducting quantum wires and quantum boxes when an electric field is present. Moreover, the TPA has more structure in quantum boxes than that in quantum wires for any direction of electric field or polarization. In addition, the ratio of the TPA in the quantum wires and boxes to that in the bulk is also calculated as a function of the photon energy both in the presence and absence of the electric field. [ABSTRACT FROM AUTHOR]

We have calculated the effect of a transverse electric field on the ground and the first few excited states of the electrons confined in a quantum wire and used these results to examine the effect of the electric field on the intersubband optical absorption in such quantum wires. The electric field removes the degeneracies between several of the excited states in the wire, which leads to peaks in the intersubband optical absorption of the wire. The application of the electric field leads to a Stark shift of the electron energies, which is quadratic in the field at low fields but becomes almost linear in the field at high fields. The electric field shifts the peaks in a manner which depends upon the polarization of the optical field with respect to the applied electric field. We have also investigated the range of wire radii and electric fields at which the infinite well model is valid in a material where the height of the confining potential barrier is finite. We have found that for small wire radii and strong electric fields, the infinite well model breaks down. [ABSTRACT FROM AUTHOR]

Abstract: Within the framework of the effective mass, the electric field effect on the optical absorption coefficient is investigated theoretically in cylindrical ZnO quantum wire (QWR). Numerical results show that the application of the electric field can decrease the strength and the threshold energy of the optical absorption coefficient in ZnO QWR. We find that there are additional oscillations in the absorption above the effective band gap, which are due to the Franz–Keldysh effect for the electric field parallel to the axis of the wire. In addition, quantum size effects on the optical absorption of ZnO QWR are also calculated. [Copyright &y& Elsevier]

Abstract: Exciton states and optical properties in wurtzite (WZ) InGaN/GaN quantum well (QW) are investigated theoretically, considering finite barrier width and built-in electric field effects. Numerical results show that when the barrier width increases, the ground-state exciton binding energy, the interband transition energy and the integrated absorption probability increase first and then they are insensitive to the variation of the barrier width. For any barrier width, the ground-state exciton binding energy and the integrated absorption probability have a maximum when the well width is 1nm; moreover, the integrated absorption probability goes to zero when the well width is larger than 6nm. In addition, the competition effects between the built-in electric field and quantum confinement are also investigated in the WZ InGaN/GaN QW. [Copyright &y& Elsevier]