AVS 47th International Symposium
    Photonics Tuesday Sessions
       Session PH-TuP

Paper PH-TuP3
Waveguiding in Microchip Lasers

Tuesday, October 3, 2000, 5:30 pm, Room Exhibit Hall C & D

Session: Poster Session
Presenter: N.J. van Druten, Leiden University and Delft Technical University, The Netherlands
Authors: N.J. van Druten, Leiden University and Delft Technical University, The Netherlands
S.S.R. Oemrawsingh, Leiden University, The Netherlands
Y. Lien, Leiden University, The Netherlands
C. Serrat, Leiden University, The Netherlands
M.P. van Exter, Leiden University, The Netherlands
J.P. Woerdman, Leiden University, The Netherlands
Correspondent: Click to Email
Microchip lasers@footnote 1@ typically consist of a thin, rare-earth-doped laser crystal, dielectrically coated on both surfaces to form a complete optical cavity. They are small and can be manufactured cheaply, because only a small amount of material is needed. Transverse-mode formation in microchip lasers is of considerable complexity, because it is the result of several competing waveguiding mechanisms, such as (i) the weak curvature of the mirrors, (ii) thermal lensing, and (iii) gain guiding (including gain-related index-guiding). The latter two depend critically on the material properties of the laser crystal. We have made a careful experimental and theoretical@footnote 2@ study of the transverse-mode formation in microchip lasers, in particular combining (i) and (iii), and concentrating on the regime where these two guiding effects have similar strength. The experiments were performed on a Nd:YVO@sub 4@ microchip laser with a plano-concave cavity configuration, longitudinally pumped by a transversely Gaussian pump beam derived from a titanium:sapphire laser. A surprisingly varied collection of mode profiles was found, deviating significantly from the standard Laguerre-Gaussian modes that are usually found for such cylindrically symmetric cases. In addition, the far-field profiles were generally found to be considerably different from the near-field profiles. We have also found cases where the far-field pattern has a minimum on axis (i.e., conical emission), while the near-field profile has an on-axis maximum. The agreement between theory and experiment is excellent, in particular when one considers the large variations in the observed mode profiles and the relative simplicity of our theoretical model. @FootnoteText@ @footnote 1@ J. J. Zayhowski and A. Mooradian, Opt. Lett. 14, 24 (1989). @footnote 2@ C. Serrat, M. P. van Exter, N. J. van Druten, and J. P. Woerdman, IEEE J. Quant. Electron. 35, 1314 (1999).