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2002

Classroom Demonstrations: Learning Tools or Entertainment?, at Physics colloquium, Swarthmore College (Swarthmore, PA), Friday, April 19, 2002:
talk_427.pdf
Classroom science demonstrations are intended to serve two important purposes: to increase students’ interest in the material being covered and to improve students’ understanding of the underlying scientific concepts. Student end-of-semester evaluations typically praise demonstrations as one of the most interesting parts of a course, suggesting that demonstrations accomplish the first objective. What about the second? Do demonstrations effectively help students learn the underlying concepts? We examined whether the mode of presentation of demonstrations affects their effectiveness as teaching... Read more about Classroom Demonstrations: Learning Tools or Entertainment?
Stopping Time, at 2002 Southern New England Regional Junior Science and Humanities Symposium, Harvard Medical School (Boston, MA), Friday, April 5, 2002:
talk_410.pdf
Ultrafast laser-processing of materials, at APS March Meeting (Indianapolis, IN), Monday, March 18, 2002:
talk_408.pdf
The dielectric function response of Te to ultrashort pulse laser excitation reveals oscillatory behavior in the bonding-antibonding split due to the presence of coherent phonons, suggesting a THz-driven semiconductor-semimetal transition.
Numerical aperture dependence of damage and white light generation from femtosecond laser pulses in bulk fused silica, at Photonics West 2002 (San Jose, CA), Thursday, January 24, 2002:
talk_421.pdf
The femtosecond laser has become an important tool in the micromachining of transparent materials. In particular, focusing at high numerical aperture enables structuring the bulk of materials. At low numerical aperture and comparable energy, focused femtosecond pulses result in white light or continuum generation. It has proven difficult to damage transparent materials in the bulk at low NA. We have measured the threshold energy for continuum generation and for bulk damage in fused silica for numerical apertures between 0.01 and 0.65. The threshold for continuum generation exhibits a minimum... Read more about Numerical aperture dependence of damage and white light generation from femtosecond laser pulses in bulk fused silica
Ultrafast laser microtexturing of silicon for optoelectronic devices, at Photonics West: Commercial and Biomedical Applications of Ultrafast Lasers (San Jose, CA), Thursday, January 24, 2002:
talk_406.pdf
Arrays of sharp, conical microstructures are obtained by texturing the surface of a silicon wafer using femtosecond laser-assisted chemical etching. The one step, maskless texturing process drastically changes the optical and electronic properties of the original silicon wafer. These properties make the textured silicon viable for use in a wide range of commercial devices. Near-unity absorption of light, from visible to infrared wavelengths, offer opportunities for use in optically active devices such as solar cells and detectors. Significant enhancement of below-band-gap photocurrent... Read more about Ultrafast laser microtexturing of silicon for optoelectronic devices

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