New wide strip and grating loaded quasi-single-mode waveguide on SOI

Area of Science:

• Photonics and Optical Engineering
• Materials Science
• Nanotechnology

Background:

• Conventional strip-loaded waveguides face challenges in higher-order mode suppression.
• Silicon-on-insulator (SOI) platforms are crucial for CMOS-compatible photonic integrated circuits.

Purpose of the Study:

• To propose and analyze a new wide single-mode strip and grating loaded waveguide.
• To enhance higher-order mode suppression in silicon nitride waveguides on SOI.
• To achieve quasi-single-mode operation with a large mode size and low propagation loss.

Main Methods:

• Numerical 3D simulations using the Finite-Difference Time-Domain (FDTD) method.
• Beam Propagation Method (BPM) simulations for waveguide analysis.
• Design and optimization of silicon nitride strip and silica cover with side gratings.

Main Results:

• The proposed waveguide structure utilizes silicon nitride strips and gratings on a silica cover over a silicon slab.
• Side gratings with a period of 0.6 micrometers and depth of 0.16 micrometers were found to be optimal.
• Achieved a high Figure of Merit for higher-order mode suppression.
• Demonstrated quasi-single-mode operation with a mode size of approximately 10 micrometers.
• Obtained a low propagation loss of approximately 0.3 dB/cm.

Conclusions:

• The novel grating-loaded waveguide design effectively suppresses higher-order modes.
• The proposed structure is CMOS-compatible and suitable for photonic integrated circuits.
• This waveguide offers a promising solution for achieving high-performance single-mode operation in silicon nitride photonics.