Micromachining transparent materials using a femtosecond laser oscillator

Presentation Date: 

Tuesday, January 23, 2001


Photonics West (San Jose, CA)

Presentation Slides: 

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 systems used in these experiments. Here we demonstrate that by focusing the laser pulses with a high numerical aperture microscope objective, one can micromachine bulk glass using an unamplified laser oscillator. 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 structurally changed. By scanning the focus through the sample, very precise, three-dimensional microstructuring can be achieved. In this talk, we discuss the morphology of single- and multiple-shot structural changes produced in bulk glass using tightly-focused femtosecond pulses from a Ti:Sapphire laser oscillator, and present our recent work on micromachining optical waveguides inside bulk glass at a 20 mm/s writing speed.