Ablation of metal targets onto pyrex glass substrates, using a Q-switched Nd:YAG laser working at 355 nm, was used to study the potential of a laser backwriting process for the fabrication of optical waveguides via an index of refraction change. Metal foils of stainless steel, aluminum, copper, brass and gold have been used as blanks and irradiated by focusing the laser beam through a cylindrical lens under continuous movement in a direction perpendicular to the irradiation. An horizontal setup was found suitable to improve the effect of the plume in the sample. Results were obtained for two different configurations. Transversal profiles were analysed using a contact profilometer, comparing results obtained for the different configurations, traverse speeds and metal targets used. Two ablation regimes were identified, which are related to a critical laser fluence value of 2.7 J/cm2. Surface micrographs obtained by scanning electron microscopy are discussed, together with the characteristics of the structures attained, taking into account the optical and thermal properties of the ablated metal blanks.

This work has been supported by Ministerio de Educación y Ciencia under the contract FEDER/TIC 2003- 03041. The Research of Antonio Castelo has been supported by a Formación de Personal Investigador (FPI) grant. The GRIN Optics Group of the University of Santiago de Compostela is a NEMO/UE (Network of Excellence on Micro-Optics) partner. Germán de la Fuente would like to acknowledge a fellowship received from the Xunta de Galicia, Consellería de Educación y Ordenación Universitaria, and DGA for financial assistance through its consolidated research group program.

7 pages, 11 figures, 3 tables.-- PACS classification codes: 78.90.+t; 42.70.Ce; 81.05.Kf; 81.15.Fg

Peer reviewed