Mode-selective modulation by silicon microring resonators and mode multiplexers for on-chip optical interconnect

Area of Science:

• Photonics
• Optical Communications
• Integrated Optics

Background:

• Mode-division multiplexing (MDM) is crucial for scaling optical communication capacity.
• Selective modulation of light carriers in MDM systems presents challenges compared to wavelength-division multiplexing (WDM).

Purpose of the Study:

• To demonstrate a scalable device for mode-selective modulation in on-chip optical interconnects.
• To enable individual processing and modulation of different light modes within a single waveguide.

Main Methods:

• Utilizing carrier-depletion add-drop silicon microring resonators for simultaneous mode de-multiplexing and high-speed modulation.
• Employing asymmetric directional coupler-based mode multiplexers to restore modulated signals.
• Designing and fabricating a proof-of-concept device with four microring resonators and a four-channel mode multiplexer.

Main Results:

• Achieved insertion losses below 2.1 dB for all modes.
• Maintained inter-mode crosstalk below -19.7 dB.
• Demonstrated clear and open optical eye-diagrams for 25 Gbps on-off key (OOK) signals, with preliminary tests at 50 Gbps.

Conclusions:

• The developed device offers enhanced manipulation flexibility for multimode optical interconnects.
• The scalable structure supports numerous mode channels, paving the way for higher communication capacities.
• This technology addresses the need for selective signal loading in advanced MDM systems.