Yu, X.Chang, ZenghuCorkum, P. B.Lei, Shuting T.2016-04-062016-04-062015-05-12http://hdl.handle.net/2097/32337Citation: Yu, X., Chang, Z., Corkum, P. B., & Lei, S. (2015). Damage formation on fused silica illuminated with ultraviolet-infrared femtosecond pulse pairs. Proceedings of SPIE. doi:10.1117/12.2182633We investigate damage formation on the surface of fused silica by two femtosecond laser pulses, a tightly focused 266 nm (UV) pulse followed by a loosely focused 800 nm (IR) pulse. We show that the damage size is determined by the UV pulse, and only a small fraction of the normal UV damage threshold energy is needed to cause damage when combined with the properly delayed IR pulse. Our results, analyzed with a rate equation model, suggest that the UV pulse generates seed electrons through multiphoton absorption and the IR pulse utilizes these electrons to cause damage by avalanche ionization. By tuning such parameters like pulse energy, time delay, IR pulse duration and polarization, we further demonstrate that damage profile can be controlled. Copyright © 2015 SPIE.This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).Avalanche IonizationFemtosecond Laser MachiningFused SilicaIr PulseMultiphoton IonizationUv PulseText