Simultaneous measurements of the intensity and phase of a probe wave reflected from an interface between silica and elemental α-gallium reveal its very strong optical nonlinearity, affecting both these parameters of the reflected wave. The data corroborate with a nonthermal mechanism of optical response which assumes appearance of a homogeneous highly metallic layer, only a few nanometer thick, between the silica and bulk α-gallium.

• Received 9 April 2001

DOI:https://doi.org/10.1103/PhysRevB.64.193312