We show that irradiation by the second harmonic (SH) of Ti:Sapphire femtosecond laser provides well-defined spots with micrometer diameter by controllable manner in pure PMMA. Combined effect of SH and fundamental frequency (FF) radiation of Ti:Sapphire laser yields significant decrease in recording time. These results relate to 3D bitwise optical information storage. Usually in order to produce irreversible detectable changes, either single amplified Ultra-Short Laser Pulse (USLP) irradiation of pure matrix or multi-shot irradiation of matrix with dyes by nonamplified USLP is employed. In our present experiments the 1.5 percent transformation of nonamplified Ti:Sapphire laser radiation into the Sh has been obtained by means of BBO crystal with thickness of 300micrometers . The SH beam was then focused within the PMMA matrix by a lens with NA equals 0.55. The onset of emission corresponds to the onset of detectable irreversible changes in PMMA detected by optical microscope. The SH provides two-photon electronic transition to the absorption band of PMMA. Theoretical analysis of experimental data shows that preliminary matrix excitation by SH is followed by a self-developing process. This process can be driven not only by SH radiation but by potentially more powerful FF radiation as well.

Date Published: 15 July 1999
PDF: 8 pages
Proc. SPIE 3618, Laser Applications in Microelectronic and Optoelectronic Manufacturing IV, (15 July 1999); doi: 10.1117/12.352712

Published in SPIE Proceedings Vol. 3618:
Laser Applications in Microelectronic and Optoelectronic Manufacturing IV
Jan J. Dubowski; Henry Helvajian; Ernst-Wolfgang Kreutz; Koji Sugioka, Editor(s)