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Confessions of a converted teacher, at Lunch Seminar, TU Delft (Delft, Netherlands), Thursday, September 22, 2011:
talk_1790.pdf
I thought I was a good teacher until I discovered my students were just memorizing information rather than learning to understand the material. Who was to blame? The students? The material? I will explain how I came to the agonizing conclusion that the culprit was neither of these. It was my teaching that caused students to fail! I will show how I have adjusted my approach to teaching and how it has improved my students' performance significantly
Confessions of a converted teacher, at TU Delft (Delft, Netherlands), Wednesday, September 21, 2011:
talk_1788.pdf
I thought I was a good teacher until I discovered my students were just memorizing information rather than learning to understand the material. Who was to blame? The students? The material? I will explain how I came to the agonizing conclusion that the culprit was neither of these. It was my teaching that caused students to fail! I will show how I have adjusted my approach to teaching and how it has improved my students' performance significantly
Nonlinear optics at the nanoscale, at Kavli Quantum Nanoscience Seminars, TU Delft (Delft, Netherlands), Wednesday, September 21, 2011:
talk_1789.pdf
We explore nonlinear optical phenomena at the nanoscale by launching femtosecond laser pulses into long silica nanowires. Using evanescent coupling between wires we demonstrate a number of nanophotonic devices. At high intensity the nanowires produce a strong supercontinuum over short interaction lengths (less than 20 mm) and at a very low energy threshold (about 1 nJ), making them ideal sources of coherent white-light for nanophotonic applications. The spectral broadening reveals an optimal fiber diameter to enhance nonlinear effects with minimal dispersion. We also present a device that... Read more about Nonlinear optics at the nanoscale
Authentic Student Learning Evaluation Plans in Higher Education, at Seminario Internacional: Metodologías Activas y Evaluación de Aprendizaje, MECESUP (Santiago, Chile), Monday, July 18, 2011
Open the doors to any classroom across the globe and you will observe an almost universal model for the evaluation of student learning. Instructors stand at the front of a lecture hall, teach content, students (at least we hope) attempt to learn that content, and then instructors evaluate that content learning through traditional assessments such as multiple-choice exams, quizzes, or research papers. Most of these conventional approaches to evaluation are one-dimensional and are not aligned with overarching learning goals that relate to competencies students actually need to progress... Read more about Authentic Student Learning Evaluation Plans in Higher Education
Silica Nanowires for Microphotonic Devices, at NSEC AP298 Seminar, Harvard University (Cambridge, MA), Monday, April 18, 2011:
talk_1743.pdf
Can light be guided by a fiber whose diameter is much smaller than the wavelength of the light? Can we mold the flow of light on the micrometer scale so it wraps, say, around a hair? Until recently the answer to these questions was "no". We developed a technique for drawing long, free-standing silica wires with diameters down to 50 nm that have a surface smoothness at the atomic level and a high uniformity of diameter. Light can be launched into these silica nanowires by optical evanescent coupling and the wires allow low-loss single-mode operation. They can be bent sharply, making it... Read more about Silica Nanowires for Microphotonic Devices
Subcellular surgery and nanosurgery, at University of Missouri St. Louis (St. Louis, MO), Wednesday, March 9, 2011:
talk_1726.pdf
We use femtosecond laser pulses to manipulate sub-cellular structures inside live and fixed cells. Using only a few nanojoules of laser pulse energy, we are able to selectively disrupt individual mitochondria in live bovine capillary epithelial cells, and cleave single actin fibers in the cell cytoskeleton network of fixed human fibro-blast cells. We have also used the technique to micromanipulate the neural network of C. Elegans, a small nematode. Our laser scalpel can snip individual axons without causing any damage to surrounding tissue, allowing us to study the function of individual... Read more about Subcellular surgery and nanosurgery
The scientific approach to teaching: Research as a basis for course design, at Tufts STEM Education Lecture Series, Tufts University (Medford, MA), Monday, March 7, 2011:
talk_1699.pdf
Discussions of teaching -- even some publications -- abound with anecdotal evidence. Our intuition often supplants a systematic, scientific approach to finding out what works and what doesn't work. Yet, research is increasingly demonstrating that our gut feelings about teaching are often wrong. In this talk I will discuss some research my group has done on gender issues in science courses and on the effectiveness of classroom demonstrations.
Nonlinear optics at the nanoscale, at Optics and Quantum Electronics Seminar, MIT (Cambridge, MA), Wednesday, February 23, 2011:
talk_1669.pdf
We explore nonlinear optical phenomena at the nanoscale by launching femtosecond laser pulses into long silica nanowires. Using evanescent coupling between wires we demonstrate a number of nanophotonic devices. At high intensity the nanowires produce a strong supercontinuum over short interaction lengths (less than 20 mm) and at a very low energy threshold (about 1 nJ), making them ideal sources of coherent white-light for nanophotonic applications. The spectral broadening reveals an optimal fiber diameter to enhance nonlinear effects with minimal dispersion. We also present a device that... Read more about Nonlinear optics at the nanoscale
Black silicon: engineering an intermediate band in silicon for optical sensing and photovoltaics, at G1 Faculty Lecture, Harvard University (Cambridge, MA), Monday, November 8, 2010:
talk_1685.pdf
Shining intense, ultrashort laser pulses on the surface of a crystalline silicon wafer drastically changes the optical, material and electronic properties of the wafer. The resulting textured surface is highly absorbing and looks black to the eye. The properties of this 'black silicon' make it useful for a wide range of commercial devices. In particular, we have been able to fabricate highly-sensitive PIN photodetectors using this material. The sensitivity extends to wavelengths of 1600 nm making them particularly useful for applications in communications and remote sensing.
Black silicon: Engineering an intermediate band for optical sensing, at National Renewable Energy Laboratory (Golden, CO), Friday, October 15, 2010:
talk_1676.pdf
Shining intense, ultrashort laser pulses on the surface of a crystalline silicon wafer drastically changes the optical, material and electronic properties of the wafer. The resulting textured surface is highly absorbing and looks black to the eye. The properties of this 'black silicon' make it useful for a wide range of commercial devices. In particular, we have been able to fabricate highly-sensitive PIN photodetectors using this material. The sensitivity extends to wavelengths of 1600 nm making them particularly useful for applications in communications and remote sensing.

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