Phase transitions induced by femtosecond pulses

Book · Tue Dec 31 04:00:00 EST 1996

OSTI ID:490818

Glezer, E N; Huang, L; Siegal, Y; Callan, J P; Mazur, E ^[1]

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1. Harvard Univ., Cambridge, MA (United States)

Optical studies of semiconductors under intense femtosecond laser pulse excitation suggest that an ultrafast phase transition takes place before the electronic system has time to thermally equilibrate with the lattice. The excitation of a critical density of valence band electrons destabilizes the covalent bonding in the crystal, resulting in a structural phase transition. The deformation of the lattice leads to a decrease in the average bonding-antibonding splitting and a collapse of the band-gap. Direct optical measurements of the dielectric constant and second-order nonlinear susceptibility are used to determine the time evolution of the phase transition. 49 refs., 9 figs.

• Sponsoring Organization: Office of Naval Research, Washington, DC (United States); National Science Foundation, Washington, DC (United States)
• OSTI ID: 490818
• Report Number(s): CONF-951155--; ISBN 1-55899-300-2
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CRYSTAL LATTICES
DIELECTRIC PROPERTIES
ELECTRONIC STRUCTURE
EXPERIMENTAL DATA
GALLIUM ARSENIDES
HARMONIC GENERATION
LASERS
OPTICAL PROPERTIES
PHASE TRANSFORMATIONS
PULSE TECHNIQUES
REFLECTIVITY