Rare-earth ion doped dielectric waveguide amplifier devices

This thesis focuses on development of fabrication technologies for Erbium-doped Al2O3 waveguides application for active integrated optical devices. The Al2O3 host layers were successfully optimized, resulting in one of the lowest loss values reported so far with a value 0.04±0.02 dB/cm at 1.55 µm. A novel procedure for deposition of Erbium-doped Al2O3 films by ALD was developed. The investigation concentrated on the repeatability of erbium concentration using identical deposition parameters, growing films of high quality and achieving excellent film uniformity over a large area on standard silicon substrates in order to have a large available area for devices. Erbium was successfully incorporated into the low-loss Al2O3 by ALD using Er(thd)3 and O2 plasma, resulting in atomic concentrations of up to 2.29 percent. X-ray Photoelectron Spectroscopy, ellipsometry and µRaman were used to analyze the films. The depth profile analysis of the films was also carried out. A new method for etching ridge waveguides by applying 85% H3PO4 was used. The structural properties of the resulting waveguides were investigated, with an emphasis on obtaining smooth sidewalls, good pattern resolution and sufficient etch depths for appropriate ridge waveguide properties. In order to validate these results, new experimental setups were realized to measure the optical gain and lifetime at C-band. For the current process, acceptable luminescence lifetimes of 4.38±0.31 ms obtained for waveguides with Er-concentrations of 1.18 atomic percent, and the highest reported optical gain per unit length of 13.72 dB/cm was demonstrated.