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Femtosecond laser microfabrication

We study the interaction of intense, femtosecond laser pulses with bulk transparent materials and use this interaction for material modification. The intensity of a femtosecond laser pulse can be high enough to cause nonlinear interactions between a transparent medium and the laser field. The material can strongly absorb energy from the laser field, producing free electrons in the material. This absorption can lead to damage or refractive index changes in the irradiated sample. The nature of the interaction between the laser pulse and the material depends on how the laser pulse is focused. When a powerful femtosecond laser pulse is tightly focused into a transparent sample, nonlinear absorption occurs only in the very small focal volume. This localization allows us to create patterns in three-dimensions inside transparent samples such as glass. For example, we have observed structures as small as 200-nm in diameter, offering exciting possibilities for high-precision microstructuring of transparent solids and for minimally disruptive laser nanosurgery.
Femtosecond laser micromachining in azopolymer films, at 2006 MRS Fall Meeting (Boston, MA, USA), Monday, November 27, 2006:
talk_1279.pdf
In this work, we investigated femtosecond laser micromachining in both poly(methyl methacrylate) (PMMA) and PMMA doped with the azoaromatic compounds Disperse Red 1 (DR1) and Disperse Red 13 (DR13). These compounds are particularly interesting due to their linear and nonlinear optical properties.
Micromachining transparent materials using a femtosecond laser oscillator, at Photonics West (San Jose, CA), Tuesday, January 23, 2001:
talk_361.pdf
The use of femtosecond laser pulses for high-precision micromachining of the surface and bulk of transparent materials has received much attention in recent years. Several groups have demonstrated the direct writing of waveguides and other photonic devices inside bulk glass using femtosecond lasers. Many of the capabilities demonstrated in these experiments offer solutions to problems the telecommunications industry is currently facing. A major obstacle, however, for industrial adoption of the techniques that have been developed is the cost and complexity of the amplified femtosecond laser... Read more about Micromachining transparent materials using a femtosecond laser oscillator
Raman studies of micro-machine glasses with variable repetition rates, at GOMD Fall Meeting 2004 (Cocoa beach, FL), Tuesday, November 9, 2004:
talk_1088.pdf
Structural changes in borosilicate and fused silica glasses modified by a femtosecond laser at different laser repetition rates were investigated. The sample was submitted to femtosecond laser pulses at a rate ranging from 1 kHz to 25 MHz in the regime where the sample could experience from a rapid cooling to a cumulative heating respectively. Changes in the glass networks of the modified region were recorded via Raman microscopy using an Ar laser at 514 nm as an excitation. Due to fluorescence background in fused silica, relative peak intensities at 605 cm-1 800 cm-1 were observed for... Read more about Raman studies of micro-machine glasses with variable repetition rates
Applications of femtosecond lasers in materials processing, at Conference on Lasers and Electro-Optics Europe (Munich, Germany), Wednesday, June 17, 2009:
talk_1438.pdf
Chemical bonding, phase transitions, and surface processes occur on timescales comparable to the natural oscillation periods of atoms and molecules, in the range of femtoseconds (1 fs =10�15 s) to picoseconds (1 ps = 10�12 s). Advances in the generation of ultrashort laser pulses in the past two decades have made it possible to directly observe these fundamental processes. These advances have taken us from the picosecond timescale a generation ago, to the femtosecond timescale in the past decade, and recently into the attosecond (1 as = 10�18 s) regime. Materials science,... Read more about Applications of femtosecond lasers in materials processing
Microexplosions: Highly supersonic plasma expansion following femtosecond laser induced breakdown, at OSA Annual Meeting (Baltimore, MD), Thursday, October 1, 1998:
talk_247.pdf
Tightly focused ultrashort laser pulses are used to produce a hot, dense plasma in water. Using time-resolved imaging and scattering techniques we map the supersonic expansion of this plasma. The expansion reaches a speed of 90 km/s, the fastest expansion witnessed to date in laser induced breakdown. Extreme temperature and pressure drive this expansion.
Interactions of Femtosecond Laser Pulses with Transparent Materials, at Physics colloquium, University of Massachusetts at Lowell (Lowell, MA), Wednesday, April 12, 2000:
talk_343.pdf
Usually when light goes through a piece of glass, nothing happens to either the light nor the glass, i.e. the glass is transparent. With a powerfull femtosecond laser pulse, however, both the laser light and the glass can be changed. We study the interaction of intense, femtosecond laser pulses with bulk transparent materials. The intensity of a tightly-focused, femtosecond laser pulse can be high enough to cause nonlinear absorption of laser energy by the transparent material. When enough energy is deposited, permanent material change results. The absorption and therefore the material... Read more about Interactions of Femtosecond Laser Pulses with Transparent Materials
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

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