Growth of a hybrid garnet crystal multilayer structure by combinatorial pulsed laser deposition

A garnet crystal multilayer structure has been grown by using the combinatorial pulsed laser deposition (PLD) technique. The structure consists of seven layers: three of them were deposited using individual Nd:Gd3Ga5O12 (Nd:GGG) and Y3Sc2Ga3O12 (YSGG) crystal targets, while the others were deposited by mixing two precursor materials in different ratios to achieve hybrid/mixed compositions. In order to investigate its crystallinity, morphology and composition, the structure has been analysed using X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). XRD analysis indicates the presence of crystalline phases in the structure and individual layers can be clearly distinguished from SEM micrographs. The elemental concentration, detected from the edge of the sample via EDX measurements, reveals a good agreement with the intended concentrations chosen for each layer. The Nd:GGG layer, characterised by a refractive index higher than that of YSGG, is located at the centre of the structure, making this structured index gradation suitable for optical wave guiding applications. The fabrication of planar waveguides with custom refractive index profiles is difficult to achieve by other techniques and this trial structure indicates the potential of PLD for use in such an application.