An O-Band III/Si Heterogeneous Integrated Laser with High Alignment Tolerance Adiabatic Coupler

Design and Simulation of O-band III/Si Heterogeneous integrated laser with high alignment tolerance adiabatic coupler is presented. To achieve high performance heterogeneous integrated III-V lasers, an adiabatic coupler structure that ensures a lossless coupling between the III-V taper and the silicon waveguide underneath is required. However, such adiabatic tapers typically have very narrow alignment tolerances, usually within tens of nanometers, making any deviation in lithography significantly reduce the coupling efficiency and deteriorate device performance. Consequently, high-precision lithography, such as electron beam lithography (EBL), is necessary for realizing III-Von silicon heterogeneous integrated lasers, potentially increasing the fabrication costs. To address this issue, we have designed an adiabatic coupler structure with high alignment tolerance. By optimizing the length and width of the adiabatic coupler, the coupling efficiency remains <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\sim$</tex> 97<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">%</sup> with misalignment up to 200nm. This design significantly reduces reliance on high-precision lithography, enables seamless integration of high-performance lasers in various photonic platforms with high device success rates.