Recently, GHz burst-mode fs laser pulses, which consists of pulse trains with extremely short intervals of several hundred ps, show superior processing characteristics in laser ablation to the conventional femtosecond laser processing (single mode) at the same average power. The GHz bursts of fs laser enables to induce ablation before the residual thermal energy deposited by preceding pulses diffuses away from the processed area, resulting in the reduction of the ablation threshold and enhancement of ablation efficiency. In this study, we apply the GHz burst mode fs laser pulses for MPP of photo-sensitive polymers to explore the effect of the burst on photochemical reaction.
Ultrashort pulsed lasers are becoming used in multiple applications thanks to their extremely short pulse durations, which confine processing within the irradiated zone and ensure a precise material ablation. However, ultrashort pulsed lasers encounter some challenges at high-speed material removal. In this situation, the use of higher power lasers for increasing ablation rates leads to detrimental effects due to heat accumulation. Recently, GHz burst mode laser ablation has been proposed as a method to overcome this limitation by applying ablation cooling.
Following this approach, we study the influence of laser irradiation parameters in burst mode on the ablation efficiency and surface microfabrication quality with special interest in the use of different wavelengths, since most studies are often limited to use the fundamental wavelength in the near infrared. Bursts of pulses used in this study contain multiple pulses happening at an ultrafast ultrafast repetition rate of 5 GHz.