Thursday, October 19, 2000
Frontiers in Chemistry and Materials Science Symposium, Lawrence Livermore National Laboratory (Livermore, CA)
Light travels undisturbed through a window pane because glass is transparent -- light and glass don't interact. With a powerful femtosecond laser pulse, however, nonlinear processes give rise to light-matter interactions that open the door to new studies in materials science, chemistry, condensed matter physics, and life sciences. Even at very modest energies, the intensity of a tightly-focused, femtosecond laser pulse can be high enough to cause nonlinear absorption of laser energy by a transparent material. The absorption is confined at the focus producing extreme conditions in the microscopic focal volume and leading to permanent structural and chemical changes can be produced. We have been able to make 200-nm wide structural changes in glass with a mere 5 nJ of laser energy. The resulting microstructures have applications in data storage, integrated opto-electronic devices, and photonic circuits. At higher intensities femtosecond lasers can be used to induce conditions approaching those found in stellar environments, allowing studies of the equation of state of matter under these extreme conditions.