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The Raman spectra of the (Dy and Y)Ba2Cu3O7-δ high-T c superconductors under various laser excitations have been measured. Using low probe powers, there are three prominent peaks at 501, 597, and 608 cm-1 in DyBaCuO, and 502, 599, and 609 cm-1 in YBaCuO besides the weak Raman features at 341, 435, and 556 cm-1. A reproducible splitting around 600 cm-1 in both samples is observed for the first time, which is not due to the presence of the Y2BaCuO5. Under moderate excitations, the splitting modes become unresolved while the 501 (or 502) cm-1 peak looks unchanged. However, only after strong laser heating, the newly appearing peak at 635 cm-1 and the triangular feature around 588 cm-1 together indicate the formation of the well-known impurity BaCuO2. But the Y2O3 compound is formed instead for the laser-treated Y2BaCuO5 sample. Our results show the significance of the laser heating effects on the interpretation of the Raman signals. The observed splitting is tentatively assigned to the nondegenerate B2g and B3g modes of the in-plane copper and oxygen vibrations which provides an alternative of distinguishing the orthorhombic from the tetragonal phase.

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The amorphous silicon film, excited by a picosecond laser, has been investigated by a laser microprobe. The optical properties are measured simultaneously with its Raman spectrum. The sharp Raman peak of this properly annealed film is similar to that of crystalline silicon (c-Si) with a significant drop in reflection. A second pulse of proper fluence can reduce the Raman intensity and increase the transmission greatly and this is ascribed to explosive crystallisation and laser quenching. This reamorphisation phenomenon of the annealed film suggests a feasible method for erasable optical recording.