Femtosecond laser microfabrication

Thresholds for femtosecond laser-induced breakdown in bulk transparent solids and water, at SPIE Annual Meeting, 1998 (San Diego, CA), Wednesday, July 15, 1998
We present thresholds for optical breakdown in bulk transparent solids and water with 100-fs laser pulses. In solids, we used microscopy and scattering techniques to determine thresholds for plasma formation and permanent damage in a wide variety of materials. Transmission measurements show that damage occurs at energies where there is little absorption of the laser pulse. In water, we used scattering and acoustic techniques to measure the breakdown threshold for 100-fs pulses. In contrast to solids, transmission measurements in water indicate that there is no plasma or bubble formation... Read more about Thresholds for femtosecond laser-induced breakdown in bulk transparent solids and water
Oscillator-only micromachining of transparent materials, at Photonics West 2000 (San Jose, CA), Monday, January 24, 2000:
By focusing femtosecond laser pulses with high numerical-aperture microscope objectives, we achieve the intensities required for bulk damage in transparent materials with energies in the range of modern laser oscillators. When a femtosecond laser pulse is tightly focused inside a transparent material, energy deposition occurs only at the focus, where the laser intensity is high enough to cause absorption through nonlinear processes. When enough energy is deposited, a localized change in the index of refraction is produced, i.e. the material is damaged. By scanning the focus through the sample... Read more about Oscillator-only micromachining of transparent materials
Materials Processing Using Ultrashort Laser Pulses, at OSA Frontiers in Optics Meeting (Tucson, AZ), Wednesday, October 19, 2005:
Ultrashort laser pulses are an important new tool in materials processing. We will discuss the physics of short-pulse laser interactions with materials and applications in micromachining and biotechnology.
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.
Three-dimensional silver nanostructure fabrication through multiphoton photoreduction, at Photonics West 2012 (San Francisco, CA), Tuesday, January 24, 2012:
We present an ultrafast laser technique for 3D direct-writing silver nanostructures embedded in a dielectric. We induce the photoreduction of silver ions through non-linear absorption in a solution doped with silver salts. Nonlinear optical interactions between the chemical precursors and femtosecond pulses limit silver-ion photoreduction processes to a focused volume smaller than that of the diffraction-limit. Our technique creates dielectric-supported silver structures, enabling the nanofabrication of silver patterns with disconnected features in 3D. We obtain sub-300 nm resolution and... Read more about Three-dimensional silver nanostructure fabrication through multiphoton photoreduction
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:
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
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:
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
Three-dimensional microfabrication with conjugated polymers, at 2006 MRS Fall Meetng (Boston, MA, USA), Thursday, November 30, 2006:
In this work we present new resin formulations containing active components, that can be polymerized by two-photon absorption in order to fabricate microstructures. The host resin we used consists of tris(2-hydroxyethyl)isocyanurate triacrylate, which gives hardness to the polymeric structure, ethoxylated(6) trimethyl-lolpropane triacrylate, which assists in decreasing the structure shrinkage upon polymerization, and ethyl-2,4,6-trimethylbenzoylphenylphosphinate, which acts as the polymerization photoinitiator. As guest material we used the conjugated polymer MEH-PPV, whose interesting... Read more about Three-dimensional microfabrication with conjugated polymers
Femtosecond laser micromachining of transparent materials, at Topical Meeting on Bragg Gratings, Photosensitivity and Poling in Glass Waveguides (Karlsruhe, Germany), Monday, June 21, 2010:
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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