Studies on Nonlinear Response of Epitaxial Ruby Thin Film

Epitaxial ruby thin film is deposited via pulsed laser deposition technique. The charateristic R-lines in PL spectra confirmed ruby phase in the film. Raman spectra showed C-axis growth of the film. The nonlinear absorption coefficient and nonlinear refractive index of film were found to be β ~ 5.2 × 10^-5 m/W and n₂ ~ 3.1 × 10^-5 m²/W, respectively. Further, the sub as well as superluminal propagation of 130-ns Gaussian pulse in 3.5-μm-thick PLD ruby thin film is reported in this paper. A delay of 17 ns is observed at film orientation of +45°, whereas pulse advancement of 12 ns is observed at -45°. Pulse broadening and compression are also observed with film rotation.