The linear and nonlinear properties of Si thin films upon Si wafers made by the use of laser ablation are presented. The linear absorption of the films clearly showed a peak at 9.8 μm (1020 cm<sup>−1</sup>), whereas the peak at 9.04 μm (1070 cm<sup>−1</sup>) from the asymmetric Si—O—Si vibration mode was absent. Raman spectroscopy data show a typical 4-cm<sup>−1</sup> downshift with respect to the Si line. The nonlinear measurements were performed with a tunable free-electron laser. The nonlinear absorption at λ=9.2 μm was measured to be approximately 2, 25, and 5 times larger than the nonlinear absorption at λ=9.0 μm, λ=9.4 μm, and λ= 9.6 μm, respectively.
© 1999 Optical Society of America
(160.0160) Materials : Materials
(190.0190) Nonlinear optics : Nonlinear optics
(240.0240) Optics at surfaces : Optics at surfaces
(300.0300) Spectroscopy : Spectroscopy
(310.0310) Thin films : Thin films
S. Vijayalakshmi, J. Sturmann, and H. Grebel, "Linear and nonlinear properties of laser-ablated Si films in the 9.09.6-μm wavelength region," J. Opt. Soc. Am. B 16, 1286-1291 (1999)