Dynamic non-linear optical processes in semiconductors

In this article active non-linear optical effects in semiconductors are reviewed. These processes arise because of the dynamics of excited populations of charge carriers temporarily created in otherwise empty states when a beam of laser radiation is incident on the material. A large number of different effects have been observed in different semiconductor materials recently and the non-linearities cover a wide range of magnitudes both in time-scale and size of non-linearity. The theory and physical concepts relevant to these processes are described and experimental observations using both high power pulsed and low power c.w. lasers are reviewed. Applications in optical bistability, phase conjugation, optical gating and optoelectronic gating are discussed.     

Eine im unteren Theile aus Milchglas bestehende Kochflasche

Ohne Zusammenfassung     

{Δ‐1,4,7,10‐Tetrakis[(S)‐2‐hydroxy­propyl‐κO]‐1,4,7,10‐tetra­aza­cyclo­do­dec­ane‐κ4N}cad­mium(II) 4‐nitrophenolate per­chlor­ate hydrate

Crystallization of [Cd(S‐thpc12)](ClO₄)₂·H₂O {S‐thpc12 is 1,4,7,10‐tetra­kis[(S)‐2‐hy­drox­y­propyl]‐1,4,7,10‐tetra­aza­cy­clo‐do­dec­ane} in the presence of sodium p‐nitrophenolate forms the title complex, [Cd(C₂₀H₄₄N₄O₄)](C₆H₄NO₃)(ClO₄)·H₂O, in which p‐nitrophenolate and water separately hydrogen bond to a different pair of cis‐related pendant hydroxyl groups which, together with the four N atoms, are themselves bound to Cd^II in an approximately square antiprismatic arrangement. The diastereoselectivity of the complex‐forming process is apparent from the fact that both different disymmetric cations in the asymmetric unit have the same Δ helicity.