An on-chip atomic layer deposited waveguide amplifier with broadband net gain

We demonstrate an erbium-doped aluminum oxide waveguide amplifier with broadband net gain. The atomic layer deposition technique is used to grow the Er3+:Al2O3. The layer-by-layer deposition allows to tailor the vertical distribution of erbium ions, by which we can change the concentration of erbium ions and prevent the clustering. We characterize the Er3+:Al2O3 film using spectroscopic ellipsometry, X-ray photoelectron spectroscopy and photoluminescence measurements. Afterwards, on-chip Er3+:Al2O3 waveguide amplifiers are fabricated. Signal enhancements of 9.6 ± 0.8 dB and 3.5 ± 0.2 dB are achieved at 1532 nm and 1550 nm, respectively, corresponding to a net gain of 4.6 ± 0.4 dB at 1532 nm. We also measure net gain at different signal wavelengths and obtain net gain from 1525 nm to 1580 nm, covering the whole C-band.