Abstract

Within the past five years, the investigation into the amplification of a weak picosecond pulse by a strong pump pulse using transient free-carrier gratings has received attention for applications in optical amplifiers and phase conjugators.^1–4 In the silicon studies,^1,2 the influence of the first-order diffractions on tire free-carrier grating played a critical rule in predicting the gain dependence vs wavemixing angle. For GaAs, an added complication is involved with an additional grating structure generated by a two-photon absorption. To our knowledge, we are the first to present a four-beam transient model of the optical multiwave-mixing process in a tree- carrier grating generated by two-photon absorption and single-photon absorption in GaAs, In addition, we observe an unusually large transfer of energy to the weak-side diffraction.

© 1993 Optical Society of America