**Laser Ablation of Polymethylmethacrylate (PMMA) by Phase-Controlled Femtosecond Two-Color Synthesized Waveforms Laser Ablation of Polymethylmethacrylate (PMMA) by Phase-Controlled Femtosecond Two-Color Synthesized Waveforms**

Ci-Ling Pan, Chih-Hsuan Lin, Chan-Shan Yang and Alexey Zaytsev Ci-Ling Pan, Chih-Hsuan Lin, Chan-Shan Yang and Alexey Zaytsev

Additional information is available at the end of the chapter Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/65637

### **Abstract**

[80] K. Venkatakrishnan, D. Vipparty, B. Tan, Nanofibre fabrication by femtosecond laser ablation of silica glass, Opt. Express. 19 (2011) 15770. doi:10.1364/OE.19.015770. [81] A. V. Rode, E.G. Gamaly, B. Luther-Davies, Formation of cluster-assembled carbon nano-foam by high-repetition-rate laser ablation, Appl. Phys. A Mater. Sci. Process. 70

334 Applications of Laser Ablation - Thin Film Deposition, Nanomaterial Synthesis and Surface Modification

(2000) 135–144. doi:10.1007/s003390050025.

Single-shot laser ablation of polymethylmethacrylate (PMMA) was studied using dualcolor waveform synthesis of the fundamental (*ω*) and its second harmonic (2*ω*) of a femtosecond Ti: Sapphire laser. Changing the relative phase of the fundamental (*ω*) and second-harmonic (2*ω*) outputs of the exciting laser resulted in clear modulation of the ablated area. The modulation as well as the dependence of the ablation threshold on the relative phase between the *ω* and 2*ω* beams correlated closely with the theoretical model of laser breakdown (ablation) of transparent materials through photoionization in the intermediate regime (Keldysh parameter *γ* ≈ 1.5). Our study illustrates the potential applications of using phase-controlled synthesized waveform for laser processing of materials.

**Keywords:** femtosecond pulses, laser ablation, coherent control, breakdown, polymethylmethacrylate (PMMA), polymer, Keldysh parameter
