1 × 4 Wavelength Demultiplexer C-Band Using Cascaded Multimode Interference on SiN Buried Waveguide Structure

Area of Science:

• Photonics and Optical Communications
• Materials Science in Photonics

Background:

• Back reflection losses are a critical performance bottleneck in silicon (Si) Multimode Interference (MMI) based wavelength division multiplexing (WDM) optical communication systems.
• Existing MMI waveguide designs, particularly those using silicon, often require specialized structures to mitigate back reflections.

Purpose of the Study:

• To propose and simulate a novel 1x4 optical demultiplexer design using silicon nitride (SiN) buried waveguides.
• To address and overcome the limitations imposed by back reflection losses in WDM systems.

Main Methods:

• Design and simulation of a 1x4 optical demultiplexer utilizing a silicon nitride (SiN) buried waveguide structure.
• Operation focused on the C-band spectrum for optical communication applications.
• Analysis of key performance metrics including power loss, bandwidth, crosstalk, and back reflection.

Main Results:

• The proposed SiN MMI demultiplexer successfully transmits four channels with 10 nm spacing in the C-band.
• Achieved low power loss (1.98-2.35 dB), large bandwidth (7.68-8.08 nm), and good crosstalk (20.9-23.6 dB).
• Demonstrated exceptionally low back reflection (40.57 dB) due to the low refractive index of SiN, eliminating the need for angled MMI designs.

Conclusions:

• The silicon nitride (SiN) demultiplexer offers a viable solution to reduce back reflection losses in WDM systems.
• This technology enables high data bitrates in optical communication by improving signal integrity.
• The proposed design provides a simpler and more effective approach compared to traditional silicon MMI technologies.