Optical coupling into deeply etched Si waveguide

Salwa El-Sabban; Diaa Khalil

doi:10.1117/12.3001527

12 March 2024 Optical coupling into deeply etched Si waveguide

Salwa El-Sabban, Diaa Khalil

Proceedings Volume 12889, Integrated Optics: Devices, Materials, and Technologies XXVIII; 128890U (2024) https://doi.org/10.1117/12.3001527
Event: SPIE OPTO, 2024, San Francisco, California, United States

Conference Poster

Abstract

Currently, grating couplers are widely used for the coupling from Single Mode Fiber SMF to Silicon Photonic waveguides. They have relatively good efficiency and they also allow surface testing of the components which is very important for the rapid testing and yield estimation of Si-Photonics circuits and their industrial wide spread. Recently, there has been an interest in Silicon waveguides with large cross section to reduce the maximum intensity in the guide and hence reduce the non-linear effects especially the two-photon absorption in Silicon ring resonators. Increasing the waveguide depth allows also lower diffraction for the output optical beam in chip-to-chip interconnection when using external mirror for beam routing and in optical sensing applications. When using the grating coupler with such deeply etched waveguides, higher order modes are usually generated in the guide and these modes are sometimes not desirable in the optical circuit to guarantee a specific optical performance. In this work, we present a design of an optical circuit for coupling power from Single Mode Fiber to the fundamental mode of a deeply etched Si waveguide with a depth of 500 nm at 1310 nm wavelength. The silicon guide is covered by silicon dioxide layer. The excitation is achieved through a grating structure designed for this purpose. The waveguide is multimode in the vertical direction and the higher order modes in this direction are filtered using a mode filter. The mode filter is based on the structure of a symmetric 3-waveguides directional coupler in which the 2 outer guides are designed to match the propagation constant of the higher order mode to be filtered. The proposed structure (grating and mode filter) achieves a coupling efficiency of about 37% for the fundamental mode of the deeply etched guide and a higher order mode rejection ratio greater than 28 dB. The structure performance is analyzed using the Finite Difference Time Domain FDTD technique.

(2024) Published by SPIE. Downloading of the abstract is permitted for personal use only.

Citation Download Citation

Salwa El-Sabban and Diaa Khalil "Optical coupling into deeply etched Si waveguide", Proc. SPIE 12889, Integrated Optics: Devices, Materials, and Technologies XXVIII, 128890U (12 March 2024); https://doi.org/10.1117/12.3001527

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available