HOME / PRESENTATIONS /

2007

Femtosecond laser-nanostructured substrates for surface enhanced Raman scattering (SERS), at Photonics West 2007 (San Jose, CA), Thursday, January 25, 2007:
talk_1297.pdf
We present a new substrate for efficient surface enhanced Raman scattering (SERS). Using a train of focused frequency-doubled femtosecond laser pulses from a regeneratively amplified Ti:Sapphire laser, we fabricate submicron surface structures on a silicon wafer. After irradiating the silicon wafer with 400nm, 100fs laser pulses in a cuvette of water, we observe the formation of an array of spikes, each approximately 500nm tall and 200nm wide. The wafer is scanned across the beam to form an arbitrarily-sized nanostructured area. When covered with a thin film of a noble metal, the structured... Read more about Femtosecond laser-nanostructured substrates for surface enhanced Raman scattering (SERS)
Femtosecond laser-nanostructured substrates for surface enhanced Raman scattering, at Photonics West 2007 (San Jose, CA), Thursday, January 25, 2007:
talk_1299.pdf
We present a new substrate for efficient surface enhanced Raman scattering (SERS). Using a train of focused frequency-doubled femtosecond laser pulses from a regeneratively amplified Ti:Sapphire laser, we fabricate submicron surface structures on a silicon wafer. After irradiating the silicon wafer with 400nm, 100fs laser pulses in a cuvette of water, we observe the formation of an array of spikes, each approximately 500nm tall and 200nm wide. The wafer is scanned across the beam to form an arbitrarily-sized nanostructured area. When covered with a thin film of a noble metal, the structured... Read more about Femtosecond laser-nanostructured substrates for surface enhanced Raman scattering
SC 541: An Introduction to Femtosecond Laser Techniques, at Photonics West 2007 (San Jose, CA), Wednesday, January 24, 2007:
talk_1247.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...
Read more about SC 541: An Introduction to Femtosecond Laser Techniques
Femtosecond laser doping of silicon, at Photonics West 2007 (San Jose, CA), Wednesday, January 24, 2007:
talk_1291.pdf
Silicon is an abundant, stable, and efficient material for use in photovoltaic devices. However, it is costly to process, and is transparent at wavelengths longer than 1100nm, a spectral region containing 25% of solar energy. The limitations of silicon have spurred significant research into complex heterostructures that capture a greater fraction of sun’s energy. Engineering silicon to extend its effective spectral range, however, might offer a simpler way to increase the efficiency and decrease the cost of silicon-based photovoltaics. We report the creation of a thin, highly absorbing layer... Read more about Femtosecond laser doping of silicon
Probing cell mechanics with femtosecond laser pulses, at Photonics West 2007 (San Jose, CA), Sunday, January 21, 2007:
talk_1288.pdf
We use femtosecond laser pulses to selectively disrupt the cytoskeleton of a living cell and probe its mechanical properties. Our nanosurgery setup is based on a home-built fluorescence microscope with an integrated femtosecond laser. We severed single actin bundles inside live cells to probe the local dynamics of the cytoskeleton and correlate it to global changes in cell shape. Simultaneous cutting and imaging allows us to study immediate cellular response with several hundred-nanometer spatial and less than 500-ms time resolution. The targeted actin bundle retracts rapidly after laser... Read more about Probing cell mechanics with femtosecond laser pulses
Applications of femtosecond laser ablation for nanoneurosurgery in C. elegans., at Photonics West 2007 (San Jose, CA), Saturday, January 20, 2007:
talk_1282.pdf
We ablate cellular material with submicrometer resolution using tightly-focused, 2-5 nJ femtosecond laser pulses. Due to the nonlinear absorption of laser light, the disruption occurs within the bulk of the sample without incision. The low energy of the pulses minimizes collateral damage. The technique has broad applicability because any optically resolvable structure within the working distance of a high-NA objective can be disrupted. Current applications of this technique include probing cytoskeletal mechanics, imaging brain tissue, and investigating the neurobiology of the nematode worm C... Read more about Applications of femtosecond laser ablation for nanoneurosurgery in C. elegans.
Wrapping light around a hair, at NSF Workshop on Nanoscale Science and Engineering Education (Arlington, VA), Friday, January 12, 2007:
talk_1293.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 Wrapping light around a hair
Using short bursts of photons to manipulate biological matter at the nanoscale, at Winter Colloquium on the Physics of Quantum Electronics (Snowbird, UT), Friday, January 5, 2007:
talk_1257.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 Using short bursts of photons to manipulate biological matter at the nanoscale

Pages