On-chip two-mode division multiplexing using tapered directional coupler-based mode multiplexer and demultiplexer.

Area of Science:

• Photonics and Optical Communications
• Integrated Optics
• Silicon Photonics

Background:

• Optical fiber communication systems face increasing bandwidth demands.
• Mode division multiplexing (MDM) offers a promising solution to enhance fiber capacity.
• On-chip implementation of MDM components is crucial for practical applications.

Purpose of the Study:

• To demonstrate a novel on-chip two-mode division multiplexing circuit.
• To integrate TE(0) and TE(1) mode multiplexer and demultiplexer functionalities.
• To evaluate the performance of the fabricated device for high-speed optical signals.

Main Methods:

• Design and fabrication of a tapered directional coupler-based mode multiplexer/demultiplexer.
• Utilized the silicon-on-insulator (SOI) platform for device fabrication.
• Conducted on-chip experiments using non-return-to-zero on-off keying (NRZ-OOK) signals at 40 Gbit/s.

Main Results:

• Achieved low insertion loss of 0.3 dB and low mode crosstalk below -16 dB.
• Demonstrated a wide operational bandwidth of approximately 100 nm.
• Exhibited large fabrication tolerance of 20 nm, with clear eye diagrams and moderate power penalty for both TE(0) and TE(1) modes at 40 Gbit/s.

Conclusions:

• The demonstrated on-chip two-mode division multiplexing circuit is a viable technology for future optical communication systems.
• The device exhibits excellent performance metrics, including low loss, low crosstalk, wide bandwidth, and fabrication tolerance.
• Successful experimental validation at 40 Gbit/s confirms the potential for high-speed data transmission.