Single-Shot Optical Conductivity Measurements of Dense Aluminum Plasma

The dielectric function of dense aluminum in the 0.1-1.5eV range was measured using frequency-domain interferometry with chirped pulses, by simultaneously measuring the optical probe reflectivity and phase shift from the rear surface of femtosecond heated aluminum foils. The optical conductivity of dense warm aluminum was extracted, based on the sharp interface at a dense plasma surface, and found to agree with calculations based on a model by Lee and More. Both free and bound electron contributions to the optical conductivity were taken into account in our calculation. The measured imaginary part of optical conductivity in this temperature range showed Ohmic like behavior. Using direct laser heating of a metal film we were able to generate electron thermal conduction waves that allowed us to create and measure the state of warm but still dense aluminum.