Abstract

We report on a study of the nanosecond dynamics of a recently discovered¹ light-induced, surface-assisted structural phase transition from a common orthorombic phase of α-gallium to a highly reflective phase. The transition has been observed at temperatures just below the metal’s bulk melting point (30°C). It is fully reversible with dynamics occurring on a nanosecond/microsecond time scale and can be stimulated by radiation of a very low intensity, typically 10⁻⁴–10⁻⁵ W/μm². The two gallium phases involved in the transition have significantly different optical properties which gives rise to a gigantic optical nonlinearity, χ⁽³⁾ ~ 1 esu offering tremendous new opportunities in controlling light with light.

© 1999 Optical Society of America