Micromachining using Ultrashort Pulses from a Laser Oscillator

Abstract:

In recent years, femtosecond laser pulses have been used to micromachine a great variety of materials. Ultrashort pulses cleanly ablate virtually any material with a precision that meets or exceeds that of other laser-based techniques, making the femtosecond laser an attractive micromachining tool. In transparent materials, where micromachining relies on nonlinear absorption, femtosecond lasers allow three-dimensional microfabrication with sub-micrometer precision. These lasers can produce three-dimensionally localized refractive index changes in the bulk of a transparent material, opening the door to the fabrication of a wide variety of optical devices. Until now micromachining of transparent materials required amplified laser systems. We recently found that transparent materials can also be micromachined using tightly focused trains of femtosecond laser pulses from an unamplified laser oscillator. In addition to reducing the cost and complexity of the laser system, femtosecond laser oscillators enable micromachining using a multiple-shot cumulative effect. We have used this new technique to directly write single-mode optical waveguides into bulk glass.