Authors:	C. Lin, M. Kiewiet, Robin R. Petit, Jolien Dendooven, N. Le Thomas, Christophe Detavernier, B. Kuyken
Title:	Ultra-Low Loss and Large Bandwidth Fiber-to-Chip Edge Coupler for Aluminum Oxide Photonic Platform At UV-Visible Wavelengths
Format:	International Journal
Publication date:	8/2025
Journal/Conference/Book:	Journal of Lightwave Technologies
Volume(Issue):	43(15) p.7265 - 7269
DOI:	10.1109/JLT.2025.3567712
Citations:	Look up on Google Scholar
Download:	(1.7MB)

Abstract

Achieving low-loss coupling between single-mode fibers and photonic integrated circuits plays a crucial role in emerging enabling technologies including quantum information, advanced imaging, and precision metrology. High coupling efficiency in the UV/visible spectrum remains challenging due to the small waveguide dimensions at shorter wavelengths. Here, we present an ultra-low loss edge coupler made of a SiOx/AlOx mode converter. The coupling loss between a standard single-mode fiber and an AlOx waveguide below 0.31 dB and 0.62 dB is experimentally demonstrated at a working wavelength of 375 nm and 405 nm, respectively. The design exhibits a large bandwidth of 110 nm below 2.6-dB loss over the entire operating wavelength range of the single mode fiber, as obtained from the simulation. This coupler not only facilitates low-loss fiber-to-chip coupling but also significantly reduces spurious light scattering, making it particularly valuable for applications in PIC-based far-field advanced microscopy and trapped-ion quantum information systems.