Presentations

    Ultrafast laser induced microexplosions: explosive dynamics and sub-micrometer structures, at Photonics West 1998 (San Jose, CA), Monday, January 26, 1998
    Tightly focused femtosecond laser pulses can be nonlinearly absorbed inside transparent materials, creating a highly excited electron – ion plasma. These conditions exist only in a small volume at the laser focus. This tight confinement and extreme conditions lead to an explosive expansion — a microexplosion. In solid materials, a microexplosion can result in permanent structural changes. We find that the damage produced by femtosecond pulses in this way is surprisingly small, with only a 200-nm diameter. Material left at the center of the microexplosion is either amorphous and less dense or... Read more about Ultrafast laser induced microexplosions: explosive dynamics and sub-micrometer structures
    Laser-induced microexplosions in transparent materials: microstructuring with nanojoules, at Photonics West 1999 (San Jose, CA), Tuesday, January 26, 1999
    We tightly focus femtosecond laser pulses in the bulk of a transparent material. The high intensity at the focus causes nonlinear absorption of the laser energy, producing a microscopic plasma and damaging the material. The tight external focusing allows high intensity to be achieved with low energy, minimizing the effects of self-focusing. We report the thresholds for breakdown and critical self-focusing in fused silica using 110-fs pulses at both 400-nm and 800-nm wavelength. We find that permanent damage can be produced with only 10 nJ (25 nJ) for 400-nm (800-nm) pulses, and that the... Read more about Laser-induced microexplosions in transparent materials: microstructuring with nanojoules
    Femtosecond laser micromachining of bulk glass at oscillator energies, at Gordon Conference on Nonlinear Optics, Colby Sawyer College (New London, NH), Tuesday, July 27, 1999:
    Using femtosecond laser pulses generated by a 25-MHz Ti:Sapphire laser oscillator, we micromachine bulk glass. The laser is focused by a 1.4 numerical aperture microscope objective, allowing the breakdown threshold to be reached with modest energies (4.5 nJ). Single-shot damage is sub-micron in size. Because the pulses arrive faster than energy can diffuse out of the focal volume, multiple shot damage with this laser is thermal in nature. Successive pulses add more and more heat to the sample, melting a micron-sized volume. Using this thermal machining, we have written single-mode waveguides... Read more about Femtosecond laser micromachining of bulk glass at oscillator energies
    Femtosecond micromachining of transparent materials, at OSA 2000 Annual Meeting (Providence, RI), Tuesday, October 24, 2000:
    By tightly-focusing femtosecond laser pulses, we achieve the intensity required for permanent structural change in transparent materials with only nanojoules of energy. We discuss the mechanisms and morphology of bulk structural changes produced by femtosecond laser pulses, and describe recent work on the direct writing of photonics devices using only a laser oscillator.
    Micromachining optical waveguides using a femtosecond laser oscillator, at Optical Society of America Annual Meeting (Providence, RI), Wednesday, October 25, 2000:
    By tightly focusing femtosecond laser pulses, we achieve optical breakdown in a transparent material using only nanojoules of laser energy. Localized structural changes are produced in the focal volume and used for bulk micromachining. Using this technique, we fabricate single-mode optical waveguides and other photonics devices inside bulk glass.
    Micromachining transparent materials using a femtosecond laser oscillator, at Photonics West (San Jose, CA), Tuesday, January 23, 2001:
    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
    Direct writing of optical waveguides in bulk glass using a femtosecond laser oscillator, at MRS Spring Meeting (San Francisco, CA), Tuesday, April 17, 2001:
    In recent years, femtosecond lasers have proven to be extremely useful for micromachining the surface and bulk of transparent materials. When a femtosecond laser pulse is focused into a transparent material, the intensity in the focal volume can become high enough to cause absorption through nonlinear processes, leading to optical breakdown and permanent structural change to the material. Because the absorption is nonlinear, this structural change can be localized in the bulk of the sample, allowing a three-dimensional structure to be micromachined. In this paper, we show that by focusing a... Read more about Direct writing of optical waveguides in bulk glass using a femtosecond laser oscillator