Recently, ultra-fast pulse lasers have been attractive in the field of fine processing applications, such as three-dimensional optical waveguides, photonic crystals and ablation.
Because femotosecond lasers have the superior characteristics of a short pulse width and high peak power, we can reduce thermal influence that causes splatters, roll up of the edge and damages of glass substrate in the thin films ablation. Due to this non-thermal ablation process, a control of the stable and fine process can be available.
In this letter, we LFT (Laserfront Technologies, Inc., former NEC Laser Solution Division) have developed a femtosecond laser system. It consists of a mode-locked fiber oscillator, a regenerative amplifier, a pulse compressor and a third harmonic generator. The gain media of the regenerative amplifier is Nd:glass. The output energy of the regenerative amplifier is 3mJ at 7 Hz repetition rate. The final THG (351 nm) output energy is 300μJ, 10% conversion efficiency was obtained. Using above femtosecond laser, we conducted ablation processing of thin films such as aluminum on the glass substrate. The results of fine processing are reported.