Abstract

Recent experiments measuring a large and ultrafast (<100 fs) nonlinear refraction in semiconductor diode lasers near their transparency edge has generated much interest owing to their potential use for all-optical switching,^1,2 We have extended an earlier model³ that successfully described the dispersion and hand-gap sealing of the electronic n₂ in passive semiconductors in their transparency range (ħω<E_g) to explain such nonlinearities in semiconductor amplifiers at photon energies near the transparency point (ħω>E_g). This simple model uses a nonlinear Kramers-Kronig transformation to obtain n₂ from a nondegenerate absorption spectrum as calculated using a "dressed-state" formalism accounting for the effects of two-photon absorption, electronic Raman, and the optical Stark shift (light-induced gaps) of the bands.

© 1992 Optical Society of America