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2000

Laser-Solid Interactions for Materials Processing, at 2000 Materials Research Science Meeting (San Francisco, CA), Wednesday, April 26, 2000:
talk_319.pdf
By focusing femtosecond laser pulses with high numerical-aperture microscope objectives, we micromachine optical glass using energies that are in the range of modern laser oscillators. When a femtosecond laser pulse is tightly focused inside a transparent material, energy deposition occurs only at the focus, where the laser intensity is high enough to cause absorption through nonlinear processes. When enough energy is deposited, a localized change in the index of refraction is produced, i.e. the material is damaged. By scanning the focus through the sample, very precise, three-dimensional... Read more about Laser-Solid Interactions for Materials Processing
Teaching and Research: Inseparable responsibilities of the modern physicist, at Advisory Committee Meeting, National Science Foundation, Directorate for Mathematical and Physical Sciences (Arlington, VA), Thursday, April 13, 2000:
talk_344.pdf
Mention the word ""physics"" to the average high-school student and you are not likely to see many happy faces. Public opinion of science in general--and physics in particular--is not high. More importantly, misunderstandings about the goals and procedures of physics are rampant. In part, these problems arise because physics education has focused nearly exclusively on generating a steady supply of future physicists. The need to educate non-majors, let alone the public at large, has generally not been perceived as an important mission of physics departments. Now that the need for physics is no... Read more about Teaching and Research: Inseparable responsibilities of the modern physicist
Interactions of Femtosecond Laser Pulses with Transparent Materials, at Physics colloquium, University of Massachusetts at Lowell (Lowell, MA), Wednesday, April 12, 2000:
talk_343.pdf
Usually when light goes through a piece of glass, nothing happens to either the light nor the glass, i.e. the glass is transparent. With a powerfull femtosecond laser pulse, however, both the laser light and the glass can be changed. We study the interaction of intense, femtosecond laser pulses with bulk transparent materials. The intensity of a tightly-focused, femtosecond laser pulse can be high enough to cause nonlinear absorption of laser energy by the transparent material. When enough energy is deposited, permanent material change results. The absorption and therefore the material... Read more about Interactions of Femtosecond Laser Pulses with Transparent Materials
Electronic and structural phase transitions induced by femtosecond laser pulses, at Seminar on Interdisciplinary Problems in Chemistry and Physics, Institute for Physical Sciences and Technology, University of Maryland (College Park, MD), Thursday, March 30, 2000:
talk_333.pdf
For over two decades the subject of laser-induced phase transitions in semiconductors has generated considerable interest. This is in part because of the technological interest of semiconductors in general and the annealing of ion-implanted semiconductors in particular. Recent experiments with ultrashort laser pulses suggest that an ultrafast transformation from an ordered semiconductor to a disordered metal takes place after excitation with intense femtosecond laser pulses. Using both linear and nonlinear optical techniques we have been able to directly observe the dielectric constant of... Read more about Electronic and structural phase transitions induced by femtosecond laser pulses
Peer Instruction: Turning a Lecture Into a Seminar, at Physics colloquium, University of Michigan (Ann Arbor, MI), Wednesday, February 9, 2000:
talk_334.pdf
Education is more than just transfer of information, yet that is mostly what happens in large introductory courses -- instructors present material and students take down as many notes as they can. This format tends to reinforce the idea that learning is about acquiring information rather than gaining new ways of thinking. In undergraduate science, however, learning consists primarily of developing new thinking skills; this mismatch between instruction and learning leads to students misunderstanding what science is, as well as frustration for both students and instructors. The problem has a... Read more about Peer Instruction: Turning a Lecture Into a Seminar

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