Micromachining with a high repetition rate femtosecond fiber laser

Abstract

Industrial micromachining applications with ultrashort pulse lasers are often difficult to make practical due to the lack of robustness of the laser and the slow processing speed resulting from the low repetition rate. In the past, amplified, femtosecond lasers produced high pulse energies, but at a slow pulse repetition rate of around a kHz. The high repetition rate oscillators did not have enough pulse energy for micromachining of most industrial materials. Fiber Chirped Pulse Amplification (FCPA) is bridging these two performance regimes, produc-ing relatively high pulse energies (compared to oscillators) and relatively high repetition rates (compared to amplifiers) in a robust and reliable package. The FCPA μJewel D-1000 has a flexible performance range that includes 10-μJ pulses at 100 kHz and 1-μJ pulses at 1 MHz. The μJ pulses at MHz repetition rates enable some interesting micromachining processes, par-ticularly with transparent dielectric materials where thermal accumulation begins to play an impor-tant role in the process. This paper expands on previously reported work on micromachining of transparent materials using a high repetition rate, femtosecond fiber laser.