Abstract

Planar A1₂O₃ waveguides were fabricated by sputter deposition of A1₂O₃ onto a thermally oxidized silicon (100) substrate. A SiO₂ layer was deposited on top of this as a cladding. The nominal layer thickness of 6µm thermal SiO₂, 0.60 µm A1₂O₃ and 1.35µm top SiO₂ result in singlemode planar waveguide films at 1.5µm. Annealing of these films at 825°C was performed to achieve a low optical loss of 0.35 dB/cm.¹ Preceding the deposition of the top cladding, 2 × 10¹⁶ Er/ cm² was implanted into the A1₂O₃ film at 1.35 MeV, with the sample held at 77 K. Using Rutherford backscattering spectrometry, an A1₂O₃ layer thickness of 430 nm and a Gaussian Erbium concentration profile at a depth of 250 nm (full width at half maximum, 135 nm) were measured. The Erbium peak concentration is 1.4 at.%. Upon excitation with an Ar-ion laser the film shows intense room temperature photoluminescence around 1.53 pm due to intra-4/ transitions in Er³⁺ (Fig. 1, solid line). The luminescence lifetime is 4.5 ms. Earlier work characterizing the photoluminescence properties of similar Er-implanted A1₂O₃ films show that high concentrations of optically active Erbium are attainable without strong concentration quenching effects.² However, cooperative upconversion was observed in films with an Erbium concentration of 3.6 at.%.

© 1994 IEEE