Low-loss Al2O3 waveguides produced by pulsed laser deposition at room temperature
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- Suárez-García, A., Gonzalo, J. & Afonso, C. Appl Phys A (2003) 77: 779. doi:10.1007/s00339-003-2212-7
Al2O3 waveguides have been produced at room temperature by pulsed laser deposition on Si substrates covered by a SiO2 buffer layer. The dependence of the refractive index and the losses on both the laser energy density and the gas used during deposition (either reactive (O2) or inert (Ar)) are discussed in terms of densification processes, surface roughness, and oxygen-related defects. Amorphous waveguides with refractive indices >1.66 and losses below 10 dB cm-1 were produced under a wide range of experimental conditions, the best results being achieved with low laser energy densities and gas oxygen pressures. Losses as low as ≈2.5 dB cm-1, which are close to the resolution limit, were achieved under optimized conditions, even when the waveguide had a thickness inhomogeneity along the propagation direction of at least 10%.