Abstract

When a magnetic field $\overline{\text{B}}$ is applied to a bulk semiconductor the lowest energy excitons retain Lorentzian lineshapes.¹ The magnetic confinement strongly modifies almost all the processes that govern the many-body nonlinearities of Lorentzian excitons (LX). Screening and carrier scattering depend strongly on whether carriers are in Landau levels or in bands. The LX internal structure experiences a contraction $\propto {\left|\overline{\text{B}}\right|}^{1/2}$ perpendicular to $\overline{\text{B}}$, and $\propto \ln \left(\left|\overline{\text{B}}\right|\right)$, along $\overline{\text{B}}$ affecting the relative motion wave function, ψ(r), and the oscillator strength ∝|ψ (0)|². The nonlinear optical response of semiconductors results from a delicate balance between Pauli Blocking (PB), Coulomb correlation (CC), and dephasing,² whose relative strengths are normally fixed by the material parameters. Application of a magnetic field, which strongly affects this balance, thus provides a perfect laboratory for studying the fundamental process that govern semiconductor nonlinearities.

© 1996 Optical Society of America