Abstract
We present a method to passively edge couple multiple optical fibers with silicon nitride waveguides in the visible wavelengths. We efficiently convert the fiber mode to the waveguide mode using an inverse taper mode size converter and support passive alignment using a U-groove that centers the optical fiber to the inverse taper. In our prototypes, we measure a coupling efficiency of −4.2 dB per facet. To reduce light leakage to the silicon substrate, we use a 6-μm oxide layer, which also eliminates the additional processes of undercutting the silicon substrate underneath the waveguide. Furthermore, the U-groove structure has a polished edge surface for coupling, reducing the steps of edge polishing the die. Fabrication of this visible-range edge coupler is complementary metal–oxide–semiconductor-compatible, making it a highly scalable method for passively packaging multiple visible-range integrated photonics devices.
Highlights
There is growing interest in silicon photonics devices due to their scalability and compatibility with the complementary metal–oxide–semiconductor (CMOS) processes
To determine the optimal inverse taper length of the mode size converter, we used the Lumerical Eigenmode expansion (EME) solver to sweep through a range of inverse taper tip widths and taper lengths
We demonstrated a passively aligned edge coupler in the visible range with a low insertion loss
Summary
There is growing interest in silicon photonics devices due to their scalability and compatibility with the complementary metal–oxide–semiconductor (CMOS) processes. Mohanty et al edge coupled a fiber onto a silicon nitride waveguide without the use of a mode size converter, and the device has an insertion loss of 16 dB.[3] Wu et al.[23] and Shin et al.[24] use U-groove for passive edge coupler alignment in conjunction with micrometer-dimension low refractive index waveguide to mode-match with the fiber. Their measured coupling losses are more than 10 dB. This work integrates the spot size converter design with U-groove passive alignment setup to facilitate the fiber-to-waveguide coupling process
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
