High-Gain Er<sup>3+</sup>:Al<sub>2</sub>O<sub>3</sub> On-Chip Waveguide Amplifiers
Mustafa Demirtaş, Feridun Ay
Abstract
High-gain on-chip Er <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> doped Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> single-mode ridge waveguide amplifier device is reported. The growth of the active layer is realized using atomic layer deposition (ALD) compatible with Si processing technology. Optimization of the Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> and Er <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> growth conditions for fine-tuning the optical properties is systematically investigated. In order to optimize the active ion concentration, heterocycle structures consisting of separately optimized Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> and Er <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> are deposited. The structural and optical properties of the active layers were characterized by spectroscopic ellipsometry, X-ray photoelectron spectroscopy, time-resolved photoluminescence, and optical gain measurements. We demonstrated up to 2.74 ± 0.40 dB total gain and 13.71 ± 1.97 dB/cm internal optical net gain per unit length at 1550 ± 12 nm using a 2-mm-long device, pumped using a 980 nm laser diode at 23-mW. This work can be expanded to other rare-earth ion doping processes, paving the way to significant improvements of active on-chip applications.