CMOS compatible ultra-compact MMI based wavelength diplexer with 60 Gbit/s system demonstration

Area of Science:

• Photonics and Optical Engineering
• Integrated Optics
• Telecommunications

Background:

• Wavelength division multiplexing (WDM) is crucial for increasing optical communication capacity.
• Existing diplexers often face challenges with size, insertion loss, and extinction ratio.

Purpose of the Study:

• To design and demonstrate an ultra-compact wavelength diplexer for 1310/1550 nm operation.
• To achieve high performance metrics including low insertion loss and high extinction ratio.
• To validate the device's capability for high-speed optical signal demultiplexing.

Main Methods:

• Design of an ultra-compact diplexer utilizing a multimode interference (MMI) coupler.
• Optimization of MMI length to 41 µm for 1550 nm operation.
• Asymmetric output port design to enhance extinction ratio.

Main Results:

• Achieved low insertion loss (< 1 dB) and high extinction ratio (> 20 dB) at 1310/1550 nm.
• Demonstrated a wide 3-dB bandwidth of 100 nm centered at operating wavelengths.
• Successfully performed on-chip demultiplexing of a 60 Gbit/s non-return-to-zero (NRZ) on-off keying (OOK) signal with clear eye diagrams.

Conclusions:

• The fabricated MMI-based diplexer is ultra-compact and offers excellent performance.
• The device is suitable for high-speed optical communication systems requiring efficient wavelength demultiplexing.