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Poster

Optoelectronic devices using femtosecond laser microstructured silicon, at NATO ASI Course on New developments in optics and related fields: modern techniques, materials, and applications, Centro Ettore Majorana (Erice, Italy), Sunday, June 12, 2005:
talk_1161.pdf
Arrays of sharp, conical microstructures are obtained by stucturing the surface of a silicon wafer using femtosecond laser-assisted chemical etching. The one step, maskless structuring process drastically changes the optical, material and electronic properties of the original silicon wafer. These properties make microstructured silicon viable for use in a wide range of commercial devices including solar cells, infrared photodetectors, chemical and biological sensors, and field emission devices.
Femtosecond laser dissection of neurons in C. elegans, at Industrial Outreach Program, Harvard University (Cambridge, MA), Wednesday, April 27, 2005:
talk_1153.pdf
Tightly-focused femtosecond laser pulses of a few nanojoules sever individual dendrites in the nematode worm C. elegans. Quantification of the resulting behavioral deficits identifies the contribution of the dissected structures. The dissection has submicrometer resolution with no collateral damage, permitting precise studies on live animals. Future work include an examination of the molecular basis of neurodegeneration that has application to diseases such as Parkinsons and Alzheimers.
Optical waveguide wiring using femtosecond laser pulses between multiple pieces of glass for optical sensor applications, at 2005 SPIE Photonics West Conference, Program on Laser Micro-/Nanoengineering and applications, Commercial and Biomedical Applications of Ultrafast Lasers VI (San Jose, CA), Tuesday, January 25, 2005:
talk_1079.pdf
We demonstrate optical waveguide wiring between multiple pieces of glass using high-repetition rate femtosecond laser pulses focused with a 1.4 NA oil-immersion microscope objective. In conventional waveguide wiring techniques, connecting optical waveguides in different pieces of glass requires special attention because of the very small core size of the waveguides. Connecting waveguides therefore necessitates highly accurate positioning stages and is a time consuming process. We demonstrate that it is possible to write optical waveguides across the gap between two pieces of glass with a... Read more about Optical waveguide wiring using femtosecond laser pulses between multiple pieces of glass for optical sensor applications
Morphology and optical properties of femtosecond irradiated glass with variable pulse repetition rates, at Glass & Optical Materials Division Fall 2004 Meeting (Cocoa Beach, FL), Tuesday, November 9, 2004:
talk_1074.pdf
We investigated the morphology of femtosecond irradiated borosilicate glass with respected to two variables: the number of shots and the laser repetition rate. For the laser repetition rate we have covered the range from 250 kHz to 25 MHz. We identify two distinct regimes of femtosecond processing in the kHz to MHz range. As the time interval between pulses is reduced, we observe a transition from a repetitive modification process (identical to what is frequently called multiple shot damage) to a cumulative thermal mechanism. In the repetitive regime, each pulse acts independently and the... Read more about Morphology and optical properties of femtosecond irradiated glass with variable pulse repetition rates
Transition from repetitive to cumulative thermal processing in femtosecond laser induced machining of embedded waveguides, at Photonics West (San Jose, California), Saturday, January 25, 2003:
talk_455.pdf
In previous work, we have demonstrated laser writing of embedded waveguides in silicate glasses with only nanojoules of energy. The laser system is an unamplified 25 MHz laser oscillator generating 24-nJ, 55-fs pulses. Laser machining at this high repetition rate results in a cumulative thermal mechanism of material modification which leads to structural index of refraction changes beyond the focal volume. We present a parametric study of the role of the laser repetition rate in the size of the machined structures. The material used for the study is a chalcogenide glass, As_2S_3. We identify... Read more about Transition from repetitive to cumulative thermal processing in femtosecond laser induced machining of embedded waveguides
Femtosecond laser-structured silicon: properties and structure, at Gordon Conference on Laser Interactions With Materials (Andover, NH), Tuesday, July 23, 2002:
talk_440.pdf
Silicon surfaces that are microstructured with femtosecond laser pulses in a sulfur hexafluoride environment exhibit several remarkable properties, including near-unity below-band gap optical absorption (C. Wu et al., Appl. Phys. Lett. 78, 1850 (2001)). We report new structural and chemical characterization of this material, including cross-sectional TEM images of the microstructures. Our results indicate that the below-band gap absorption most likely comes from a surface layer of polycrystalline silicon roughly 1 micrometer thick, which includes nanopores, nanocrystals, and a high... Read more about Femtosecond laser-structured silicon: properties and structure
Assessing the initial state of knowledge of first-year genetics students, at ASM Eighth Undergraduate Microbiology Education Conference, American Society for Microbiology (Orlando, FL), Saturday, May 19, 2001:
talk_384.pdf
A survey was designed to assess students' understanding of concepts and familiarity with biology terminology at the beginning of a new introductory genetics course. The class, which serves as the first college biology course for all students majoring in Biological Sciences or fulfilling premedical requirements, assumes no prior knowledge and enrolls mainly first-year students. The survey asked students to rate their familiarity with over 80 words in genetics and to define a selection of these terms. Students were also asked to answer a few conceptual questions as well as provide background... Read more about Assessing the initial state of knowledge of first-year genetics students

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