Structural and optical properties of rare-earth-doped Y 2O 3 waveguides grown by pulsed-laser deposition

Abstract

Crystalline rare-earth-doped yttrium oxide thin films were grown by pulsed-laser deposition (PLD) on SiO 2/Si substrates. The structural and morphological features of these films were studied, as a function of the growth conditions (temperature from 200 to 800°C and oxygen pressure from 10 -6 to 0.5 mbar), by using Rutherford backscattering spectroscopy, x-ray diffraction, and atomic force microscopy. The related optical properties were investigated by m-lines spectroscopy at 633 nm and 1.3 μm. The optimal conditions were found to be a temperature and a pressure of 700°C and 10 -6 mbar, respectively. In that case, the Y 2O 3 films are stoichiometric with controlled erbium and europium rates, and present a well-crystallized, (111) textured cubic phase and a low surface roughness of about 10 Å. Moreover, the PLD films show good waveguiding properties with a high refractive index (1.92 at 633 nm), a step-index structure, and low optical losses around 1 dB/cm in the near infrared region, promising for a planar amplifier function. © 2002 American Institute of Physics.