Broadband and High-Density Interposer based on Ultrafast Laser Inscribed Waveguides

Photonic integrated circuits are enabling innovation in high-speed optical communication, machine learning and artificial intelligence, and quantum computing [1]. The photonic platform of choice for these applications is silicon-on-insulator, because it can rely on decades of research and investment by the semiconductor industry that has establish highly automated and robust processes for mass fabrication [2]. Silicon photonics offers a high-integration density due to its large refractive index contrast between the crystalline silicon waveguide core and vitreous silica cladding. Yet, optical transmission of information uses optical fibres, which are geometrically one order of magnitude larger. This makes low-loss coupling between optical fibres and silicon photonic waveguides challenging [3].