Net optical gain at 1.53 µm in Er-doped Al2O3 waveguides on silicon

A 4 cm long Er-doped Al₂0₃spiral waveguide amplifier was fabricated on a Si substrate, and integrated with wavelength division multiplexers within a total area of 15 mm². When pumped with 9 mW 1.48 µm light from a laser diode, the amplifier shows 2.3 dB net optical gain at 1.53 µm. The gain threshold was 3 mW. The amplifier was doped with Er by ion implantation to a concentration of 2.7X 10²⁰ cm^-3. The data agree well with calculations based on a model which includes the effects of cooperative upconversion and excited state absorption. For an optimized amplifier, net optical gain of 20 dB is predicted.