2006

Silica nanowires: manipulating light at the nanoscale, at Photonics West 2006 (San Jose, CA), Thursday, January 26, 2006:

talk_1184.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: manipulating light at the nanoscale

Ultrafast Frequency Dynamics of Coherent Phonons in Te Under High Density Photoexcitation, at Photonics West 2006 (San Jose, CA), Wednesday, January 25, 2006:

talk_1178.pdf

We report on the ultrafast dynamics of large amplitude A1 coherent optical phonons in Te after excitation with femtosecond laser pulses. Using time-resolved pump-probe dielectric tensor measurements on a single crystal Te sample we can monitor the excitation of the A1 phonon mode due to photoexcited carrier density redistribution. By performing a short-term Fourier transform of the observed dielectric tensor oscillations we can track the evolution of their local frequency and determine the time-resolved frequency response of the photoexcited A1 phonon mode.

The purpose of the experiment...

Femtosecond micromachining of waveguides in a Faraday material, at Photonics West 2006 (San Jose, CA), Tuesday, January 24, 2006

The use of femtosecond lasers for micromachining purposes has grown significantly over the past decade. Femtosecond micromachining of photonic devices has been demonstrated using only a few nanojoules of energy from a laser oscillator. This oscillator-only technique has recently become increasingly valuable as a micromachining tool.

Faraday isolators have not yet been realized using this ultrafast micromachining technique. A Faraday isolator is an important device because it functions as an optical diode, allowing signals to propagate only in one direction. It is particularly useful in...

Femtosecond-laser microstructuring of silicon for photovoltaic devices, at Photonics West 2006 (San Jose, CA), Tuesday, January 24, 2006:

talk_1174.pdf

Photovoltaics research has recently focused on photovoltaic materials made by cheaper processes with minimal waste such as thin-films grown by chemical vapor deposition. Because silicon is the most common semiconductor material and the second most abundant element in the earth, silicon-based thin films are an excellent choice for photovoltaics. The drawback to crystalline silicon thin films is low absorption due to silicons indirect band gap. Thicker films increase processing costs and sacrifice efficiency due to defects inherent in the thin-films.

We report the creation of a thin,...

Femtosecond laser micromachining, at Photonics West 2006 (San Jose, CA), Tuesday, January 24, 2006:

talk_1182.pdf

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.

Sub-cellular nanosurgery in live cells using ultrashort laser pulses, at Photonics West 2006 (San Jose, CA), Sunday, January 22, 2006:

talk_1176.pdf

We use femtosecond laser pulses to selectively disrupt the cytoskeleton of a living cell and probe its mechanical properties. The nanosurgery setup is based on a home-built two-photon microscope. To image, we use a 80-MHz, 100-pJ/pulse laser beam, which is scanned across the sample; to cut, we introduce a second, 250-kHz, 1 to 5-nJ/pulse, laser beam and locally ablate sub-cellular structures. Simultaneous cutting and imaging allows us to study immediate cellular response with several hundred-nanometer spatial and less than 500-ms time resolution.

We severed single actin bundles inside...

SC 541: An Introduction to Femtosecond Laser Techniques, at Photonics West 2006 (San Jose, CA), Sunday, January 22, 2006:

talk_1189.pdf

General Course Description: This interactively taught half-day course provides basic knowledge of the measurements of and research with femtosecond laser pulses. Beginning with the basic principles of the interaction of light and matter, we'll discuss the interaction of intense short pulses with matter. Using worksheets we'll address a number of common conceptual misconceptions in an interactive and collaborative setting.

Benefits Learning outcomes:

This course will enable you to

Explain the basis for the electronic and optical properties of...

Single neuron dissection in C. elegans by femtosecond laser pulses, at Photonics West 2006 (San Jose, CA), Saturday, January 21, 2006:

talk_1179.pdf

Using tightly-focused, 2-5 nJ femtosecond laser pulses we disrupt cellular material in the nematode worm C. elegans. Due to the nonlinear absorption of laser light, the dissection has submicrometer resolution, yielding surgery within the bulk of the worm without incision. The low energy of the pulses minimizes collateral damage. This technique permits subcellular surgery on live animals and opens a wide range of neurobiological questions to study in vivo.

We severed individual dendrites of a thermosensory neuron without damaging nearby neurons. Quantification of the resulting behavioral...

Reversible birefringence in microstructures, at CLEO 2006 (Longbeach, CA, USA), Thursday, January 5, 2006:

talk_1276.pdf

We use two-photon absorption polymerization to fabricate optically active microstructures that exhibit optically-induced birefringence and dichroism. Our results open the door to new applications in data storage, waveguides and optical circuitry

Subcellular surgery and nanoneurosurgery, at 36th Winter Colloquium on The Physics of Quantum Electronics (Snowbird, UT), Wednesday, January 4, 2006:

talk_1185.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 nanoneurosurgery

2006

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HARVARD UNIVERSITY

Harvard John A. Paulson SEAS
Department of Physics

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Prof. Eric Mazur, Department of Physics
Harvard University, Cambridge, MA 02138

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