Epitaxial Sr₁.₈Ca₀.₂NaNb₅O₁₅ thin film waveguides grown by pulsed laser deposition: optical properties and microstructure

Abstract

Epitaxial Sr₁.₈Ca₀.₂NaNb₅O₁₅ (SCNN) thin films slab waveguide structures that support several low-loss transverse electric (TE) and transverse magnetic (TM) modes were grown on MgO(100) substrates by pulsed laser deposition. To optimize the waveguiding properties, the relationship between film microstructure and deposition temperature was investigated by x-ray diffraction, atomic force microscopy, and scanning electron microscopy. The prism coupler technique provides for the refractive indices and structural anisotropy of the core SCNN films deposited at various temperatures. Characterization based on this technique is proposed as a mean to relate the surface morphology to optical features such as the full width at half maximum of the excited guide mode.