Design, Growth, and Characterization of Semiconductor Optical Amplifier Structures with Wide Spectral Bandwidth in C+L Bands

In this article, we present two designs of semiconductor optical amplifiers intended for amplification in the C and L bands of fiber-optic telecommunications. The active layers consist of strained quantum wells under compression to ensure strong TE mode. The designs are engineered to generate gain over a wide bandwidth through emission associated with the main electronic transitions $\mathrm{e}_{1}-\mathrm{hh}_{1}$ and $\mathrm{e}_{2}-\mathrm{hh} \mathrm{h}_{2}$. We outline the fabrication processes as well as the optical characterizations of two components consisting of 11 and 14 nm thick quantum well active layers. The bandwidths determined in amplified spontaneous emission measurements exhibit broadband characteristics, especially for the design with larger quantum wells. The gain reaches values of 25 and 34.8 dB, with associated bandwidths of at least 71 and 90 nm, respectively. Lastly, the low beam divergence determined in far-field measurements confirms excellent potential for coupling with optical fiber.