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2001

Direct writing of optical waveguides in bulk glass using a femtosecond laser oscillator, at MRS Spring Meeting (San Francisco, CA), Tuesday, April 17, 2001:
talk_366.pdf
In recent years, femtosecond lasers have proven to be extremely useful for micromachining the surface and bulk of transparent materials. When a femtosecond laser pulse is focused into a transparent material, the intensity in the focal volume can become high enough to cause absorption through nonlinear processes, leading to optical breakdown and permanent structural change to the material. Because the absorption is nonlinear, this structural change can be localized in the bulk of the sample, allowing a three-dimensional structure to be micromachined. In this paper, we show that by focusing a... Read more about Direct writing of optical waveguides in bulk glass using a femtosecond laser oscillator
Femtosecond Techniques for Materials Scientists, at Tutorial Q at the MRS Spring Meeting (San Francisco, CA), Monday, April 16, 2001:
talk_374.pdf
Femtosecond Techniques 1. Linear and nonlinear propagation of light a. Propagation of electromagnetic waves in dense media b. Dielectric function c. Lorentz equations, Drude model d. Pulse dispersion c. Nonlinear response f. Second harmonic generation and inversion symmetry (*) g. Self phase modulation and self-focusing h. Continuum generation 2. Femtosecond measurements a. Pump-probe technique b. Dispersion compensation techniques (*) c. Representation of pulses; Wigner representation d. Temporal characterization of pulses e. Joint time-frequency measurements (*) f. Frequency-resolved... Read more about Femtosecond Techniques for Materials Scientists
Laser-induced microexplosions in transparent solids and liquids, at Physics Seminar, University of Missouri-Rolla (Rolla, MI), Friday, April 13, 2001:
talk_380.pdf
Using femtosecond laser pulses we study the effects of intense laser radiation on transparent materials. By tightly focusing these laser pulses below the surface of transparent materials, we initiate highly nonlinear absorption processes which produce a dense, highly-excited plasma inside the sample. The high density, tightly-confined plasma leads to a micron-sized explosion within the material, with temperatures and pressures approaching stellar conditions. We have recently shown that it is possible to create internal submicron-sized structures by optically initiating microexplosions inside... Read more about Laser-induced microexplosions in transparent solids and liquids
Memorization or Understanding: Are we teaching the right thing?, at Physics Colloquium, University of Missouri-Rolla (Rolla, MI), Thursday, April 12, 2001:
talk_379.pdf
Education is more than just transfer of information, yet that is what is mostly done in large introductory courses -- instructors present material (even though this material might be readily available in printed form) and for students the main purpose of lectures is to take down as many notes as they can. Few students have the ability, motivation, and discipline to synthesize all the information delivered to them. Yet synthesis is perhaps the most important -- and most elusive -- aspect of education. Students get frustrated because they are unable to grasp simple concepts. Instructors get... Read more about Memorization or Understanding: Are we teaching the right thing?
Memorization of Understanding: Are we teaching the right thing?, at Lincoln Laboratory Distinguished Lecture, MIT Lincoln Laboratory (Lexington, MA), Thursday, March 8, 2001
Education is more than just transfer of information, yet that is what is mostly done in large introductory courses instructors present material (even though this material might be readily available in printed form), and for students the main purpose of lectures is to take down as many notes as they can. Few students have the ability, motivation, and discipline to synthesize all the information delivered to them. Yet synthesis is perhaps the most important and most elusive aspect of education. Instructors get frustrated because they don t know how to help their students grasp the material.... Read more about Memorization of Understanding: Are we teaching the right thing?
Stopping Time, at Public Lecture, University of Puerto Rico, Rio Piedras (San Juan, PR), Tuesday, March 6, 2001:
talk_371.pdf
Time is of philosophical interest and is also the subject of mathematical and scientific research. Even though it is one of the most familiar concepts, the passage of time remains one of the greatest enigmas of the universe. The Platonist Augustine has said: 'What then is time? If no one asks me, I know what it is. If I wish to explain it to him who who asks me, I do not know.' The concept time can indeed not be explained in simple terms. Emotions, life and death all are related to our interpretation of the irreversible flow of time. The more we think about it, however, the more unclear the... Read more about Stopping Time

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