High-Precision Material Processing by Femtosecond Laser pra-0083

Full Title Studies of High-Precision Material Processing by Ultra-Short, High-Powered Laser Radiation: a Step Toward Femtosecond Machining Tech Area / Field

PHY-OPL: Physics / Optics and Lasers

MAN-MCH: Manufacturing Technology / Machinery and Tools

MAT-SYN: Materials / Materials Synthesis and Processing

Brief Description of Technology The proposed project is aimed at carrying out studies of interactions between ultra-short, strong optical fields with intensities of 10¹⁴-10¹⁷ W/cm² and solid-state targets. The main idea of the investigations rests on the fact that femtosecond intense laser pulses produce a high energy concentration on the surface of irradiated matter within short time intervals, providing plasma formation and ablation without essential energy coupling into the bulk of material. In this manner, favorable conditions are attained for increased ablation efficiency at minimal thermal and shock stresses—resulting in the precise, pulse-by-pulse modification of the irradiated surface. These regimes of ablation offer the potential for high-precision processing of materials ranging widely from metals (steel, alloys) to dielectrics (ceramics, diamonds, biomaterials, polymers). This attractive application for material processing demands a thorough study of laser-plasma interaction using different materials, novel optical diagnostics and theoretical simulations of interaction regimes.

Legal Aspects None.

Special Facilities in Use and Their Specifications We have a homemade femtosecond Ti:Sa laser facility with a pulse energy of 1-5 mJ, a repetition rate of 20 Hz and a focal intensity of up to 10¹⁷ W/cm². The facility is used in experiments on super-strong field interaction with gaseous and solid-state media. To investigate dynamic properties of laser-produced solid-density plasmas, several optical diagnostics with temporal resolution of the order of 10 fs will be used — including different versions of multi-color pump-probe techniques, frequency resolved optical gating, high-order harmonic detection, etc. To analyze laser-plasma properties and ablation regimes, unique multichannel absolutely calibrated X-rays detectors — in the wavelength range 10-100 nm — are exploited. For the surface diagnostics, AFM, STEM and SNFM facilities will be used.

Scientific Papers B.Luk’yanchuk, N.Bityurin, M. Himmelbauer, N.Arnold, “UV-laser ablation of Polyimide: from long to ultra-short laser pulses,” Nuclear Instr. and Methods in Physics Research B. v.122, p.347 (1997).

N.Bityurin, A. Malyshev, B. Luk’yanchuk, S. Anisimov, D. Baeuerle, “Photophysical mechanism of UV laser action: the role of stress transients,” Proc. SPIE , v. 2802, p.103 (1996).

N.Arnold, D.Baeuerle, B.Luk’yanchuk, N.Bityurin, S.Anisimov, A.Malyshev, “Photophysical ablation of organic polymers: the influence of stresses,” Applied Surface Science, v.106, p.120 (1996).

B. Luk’yanchuk, N. Bityurin, S. Anisimov, and D. Baeuerle, “The Role of Excited Species in UV-Laser Material Ablation, Part I: Photophysical Ablation of Organic Polymers,” Appl. Phys. A 57, p.367 (1993).

C.W.Siders, N.C.Turner III, M.C.Downer, A.Babin, A.Stepanov, A.Sergeev, “Blueshifted third harmonic generation during ultrafast barrier suppression ionization of subatmospheric density noble gases,” JOSA B, v.13, N 2, p.330 (1996).