Presentations

    Subcellular surgery and nanosurgery, at CLEO 2007 (Baltimore, MD), Thursday, May 10, 2007:
    We use femtosecond laser pulses to probe the mechanical propertiesof the actin network in live cells and to probe cell regeneration and the neurological basis of behavior in C. elegans.
    Wrapping light around a hair, at Advances on Nanophotonics II, Centro Ettore Majorana (Erice, Italy), Tuesday, June 26, 2007:
    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 Wrapping light around a hair
    Nonlinear optics at the nanosale, at Ultrafast Optics 2007 (Santa Fe, NM), Wednesday, September 5, 2007:
    Silica nanowires are a model system for the propagation of light at the nanoscale. Because of the tight confinement of light provided by these nanowires, nonlinear effects can be observed with pulse energies in the picojoule range, opening the door to a new class of nanophotonic devices. In addition, silica nanowires permit convenient coupling between macroscale and nanoscale. We will show how silica nanowires can be used to study waveguiding, mode propagation, and nonlinear effects in single ZnO nanowires.
    Interactive Teaching: Turning a Large Lecture into a Seminar, at MIT Mechanical Engineering Teaching and Learning Retreat, Massachusetts Insitute of Technology (Cambridge, MA 02138), Sunday, September 23, 2007:
    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 Interactive Teaching: Turning a Large Lecture into a Seminar
    Introduction to Peer Instruction, at AAPT New Faculty Workshop, American Center for Physics (College Park, MD), Thursday, November 8, 2007:
    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.
    Peer Instruction Workshop, at AAPT New Faculty Workshop, American Center for Physics (College Park, MD), Friday, November 9, 2007:
    The basic goals of Peer Instruction are to encourage and make use of student interaction during lectures, while focusing students' attention on underlying concepts and techniques. The method has been assessed in many studies using standardized, diagnostic tests and shown to be considerably more effective than the conventional lecture approach to teaching. Peer Instruction is now used in a wide range of science and math courses at the college and secondary level. In this workshop, participants will learn about Peer Instruction, serve as the “class” in which Peer Instruction is demonstrated,... Read more about Peer Instruction Workshop
    High photoconductive gain and broad spectral sensitivity enabled by femtosecond laser doping of silicon, at SPIE Photonics West 2008 (San Jose, CA), Wednesday, January 23, 2008:
    Femtosecond laser doping of silicon produces near-unity absorption from the ultraviolet to the short wave infrared. The resulting ‘black silicon’ has great potential for applications in photoactive devices. We have successfully incorporated black silicon into new silicon devices with unique characteristics including: high efficiency, room-temperature photoconductive gain, broad-spectral silicon photodetection, and enhanced near-infrared photovoltaic response. We present the current state of the research and discuss the potential for this processing technique to develop other new materials.
    Wrapping light around a hair, at NCLT Faculty Workshop on Nanoscale Science & Engineering Education, Alabama A&M University (Huntsville, AL), Thursday, March 27, 2008:
    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 Wrapping light around a hair
    Memorization or understanding: are we teaching the right thing?, at NCLT Faculty Workshop on Nanoscale Science & Engineering Education, Alabama A&M University (Huntsville, AL), Friday, March 28, 2008
    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. I will show how shifting the focus in lectures from delivering information to synthesizing... Read more about Memorization or understanding: are we teaching the right thing?
    The interactive learning toolkit: technology and the classroom, at Canadian Association of Physicists Congress, Laval University (Quebec, Canada), Tuesday, June 10, 2008:
    It has been suggested the lack of interaction in large lecture courses is to blame for the many problems facing these courses: declining enrollments, low attendance, poor evaluations, and disappointing retention. We offer a way of redesigning the classroom so interaction is introduced in many aspects of the course. This approach has shown to be effective by many instructors in a broad variety of environments. I will demonstrate some of the tools we have developed to foster this interaction.
    Introduction to Peer Instruction, at AAPT New Faculty Workshop, American Center for Physics (College Park, MD), Wednesday, June 25, 2008
    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.
    Introduction to Peer Instruction, at AAPT New Faculty Workshop, American Center for Physics (College Park, MD), Thursday, June 26, 2008:
    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.
    Peer Instruction Workshop, at AAPT New Faculty Workshop, American Center for Physics (College Park, MD), Friday, June 27, 2008:
    The basic goals of Peer Instruction are to encourage and make use of student interaction during lectures, while focusing students' attention on underlying concepts and techniques. The method has been assessed in many studies using standardized, diagnostic tests and shown to be considerably more effective than the conventional lecture approach to teaching. Peer Instruction is now used in a wide range of science and math courses at the college and secondary level. In this workshop, participants will learn about Peer Instruction, serve as the “class” in which Peer Instruction is demonstrated,... Read more about Peer Instruction Workshop
    Nonlinear optics at the nanoscale: all-optical logic gates, at Julius Springer Forum on Applied Physics, Harvard University (Cambridge, MA), Saturday, September 27, 2008:
    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: all-optical logic gates
    Optically hyperdoped silicon, at The 39th Winter Colloquium on the Physics of Quantum Electronics (Snowbird, UT), Thursday, January 8, 2009:
    By irradiating silicon with a train of femtosecond laser pulses in the presence of chalcogen (column VI) compounds, a thin layer of Si is doped to previously unreported, non-equilibrium levels (about 2%). This optical hyperdoping (OHD) process creates a highly absorbing surface and extends silicon’s spectral sensitivity, even for infrared photons with energy less than the band gap. The optoelectronic properties of this 'black silicon' make it useful for a wide range of commercial devices in communications, remote sensing, and solar energy harvesting. Prototype OHD silicon photodiodes exhibit... Read more about Optically hyperdoped silicon
    Disseminating Curriculum and Pedagogy: Peer Instruction, at Joint AAPT/AAAS 2009 Annual Winter Meeting (Chicago, IL), Saturday, February 14, 2009:
    I coined the term "Peer Instruction" (and the associated "ConcepTests") to describe a technique I was starting to implement in my class in an NSF proposal I wrote 1991. I implemented the technique to solve a problem in my own class, never anticipating the wide acceptance the technique (and the terms) would find over the course of the next decade and a half. The technique has found a broad following across disciplines, across institutions, and across the world, even if some adaptations stray far from my original ideas. What is it that accounts for the method's rapid dissemination? Does the... Read more about Disseminating Curriculum and Pedagogy: Peer Instruction
    Technology is not a pedagogy: Peer Instruction with and without clickers, at 2009 AAPT Winter Meeting (Chicago, IL), Monday, February 16, 2009:
    Peer Instruction is an instructional strategy for engaging students during class using a structured questioning process. Results from a wide variety of institutions indicate that Peer Instruction increases student mastery of conceptual reasoning and quantitative problem solving and decreases attrition rates. The technique is most frequently implemented with clickers, even though flashcards or raised hands can also be used. We recently studied the effect of clickers on the implementation of Peer Instruction and found that the benefits result more from the pedagogy than from the clicker... Read more about Technology is not a pedagogy: Peer Instruction with and without clickers
    Femtosecond laser micromachining for applications in microphotonics, at E-MRS Meeting (Strassbourg, France), Thursday, June 11, 2009:
    When femtosecond laser pulses are focused tightly into a transparent material, the intensity in the focal volume can become high enough to cause nonlinear absorption of laser energy. The absorption, in turn, can lead to permanent structural or chemical changes. Such changes can be used for micromachining bulk transparent materials. Applications include data storage and the writing of waveguides and waveguide splitters in bulk glass, fabrication of micromechanical devices in polymers, and subcellular photodisruption inside single cells.

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