Demultiplexing-free ultra-compact WDM-compatible multimode optical switch assisted by mode exchanger

Area of Science:

• Photonics and Optical Engineering
• Integrated Optics
• Semiconductor Devices

Background:

• Silicon-based optical switches are crucial for on-chip optical interconnects.
• Mode-division multiplexing (MDM) increases optical switch link capacity but traditional designs are complex and bulky.
• Existing multimode optical switches often rely on Mach-Zehnder interferometer (MZI) structures and mode (de)multiplexers, leading to large footprints.

Purpose of the Study:

• To propose and experimentally demonstrate a novel demultiplexing-free dual-mode 3x3 thermal-optical switch.
• To achieve a compact and efficient optical switch design for on-chip applications.
• To enable separate routing of TE0 and TE1 modes using micro-rings and mode exchangers.

Main Methods:

• Utilized micro-rings (MRs) designed for TE1 mode and mode exchangers (MEs) to convert TE0 to TE1 mode.
• Employed Bezier curves for optimizing MEs and dual-mode waveguide bends (45° and 90°) for compact layout.
• Integrated multiple wavelength channels and spacings by adding MR pairs for WDM compatibility.

Main Results:

• Demonstrated an ultra-compact switch footprint of 0.87 x 0.52 mm².
• Achieved insertion losses below 8.7 dB at 1551 nm and optical signal-to-noise ratios (OSNRs) exceeding 13.0 dB.
• Validated high-speed transmission capability through 32 Gbps data transmission experiments.

Conclusions:

• The proposed demultiplexing-free dual-mode switch offers a compact and efficient solution for on-chip optical interconnects.
• The design exhibits strong WDM compatibility and high-speed data transmission capabilities.
• This technology advances the development of next-generation optical routing devices.