IMPROVED TRANSPARENCY EFFICIENCY TRADE-OFF IN A NEW CLASS OF NONLINEAR ORGANOSILICON COMPOUNDS

Synthesis and characterization of a new class of organosilicon compounds with a wide transparency range and enhanced nonlinear optical properties are presented. The quadratic hyperpolarizabilities (beta) have been measured by the electric field induced second-harmonic generation (EFISH) technique. The effectiveness of the trimethylsilyl substituent is tested both as an electron-donor and as an electron-acceptor group in adequately substituted compounds. Experimental results support evidence that (CH3)3Si is markedkly more efficient as an electron-releasing group. Si has also been included as part of the conjugation path connecting two and three phenyl rings. It is found to be a weak charge transmitter when donor and acceptor phenyl-Si-phenyl moieties are connected. A vectorially additive model of beta's is then shown to account satisfactorily for such an interaction.