a1 Nagoya Institute of Technology, Showa Nagoya, 466 Japan
a2 Nagoya University, Chikusa Nagoya, 464 Japan
Cu2+-containing SiO2 and Al2O5 · 9SiO2 glasses were prepared by the sol-gel method and heated under reducing conditions to precipitate small-sized Cu and Cu2O erystals. Cu2+ ions incorporated in SiO2 glass were reduced by heating in N2 to precipitate Cu2O and in H2 to precipitate Cu microcrystals with diameters of about 5 to 15 nm. Microcrystalline Cu-precipitated glass showed an optical absorption band at 560 nm and its third-order nonlinear susceptibility was 1.25 × 10−10 esu, which originated from the enhancement by the surface plasmon resonance of Cu particles. In contrast, Cu2+ ions incorporated in Al2O3 · 9SiO2 glass remained unchanged after heating in the reducing gas atmospheres.
(Received December 20 1994)
(Accepted June 08 1995)