Full C-band Si photonic crystal waveguide modulator

Area of Science:

• Photonics
• Optical Communications
• Materials Science

Background:

• Silicon photonic crystal waveguides (LSPCW) offer compact phase shifters due to the slow-light effect.
• However, the slow-light effect inherently limits the operational bandwidth (Δλ) of these devices.
• Mach-Zehnder modulators are key components in optical communication systems.

Purpose of the Study:

• To optimize the structural parameters of lattice-shifted photonic crystal waveguides (LSPCW).
• To extend the working spectrum (Δλ) of LSPCW Mach-Zehnder modulators to cover the full C-band.
• To maintain high-speed modulation performance within the broadened spectrum.

Main Methods:

• Structural parameter optimization of LSPCWs.
• Fabrication of optimized LSPCW Mach-Zehnder modulators.
• Characterization of operational spectrum (Δλ) and group index (n_g).
• High-speed performance testing (e.g., eye diagram analysis at 25 Gbps).

Main Results:

• Achieved an extended working spectrum (Δλ) of 42 nm, covering the full C-band.
• The group index (n_g) was moderately decreased to 8-9.
• Demonstrated 25 Gbps eye opening in a 200 μm modulator across the full C-band.
• Successful fabrication of the optimized device.

Conclusions:

• Optimized LSPCWs can effectively extend modulator bandwidth to the full C-band.
• The trade-off between bandwidth extension and group index is manageable for high-speed applications.
• These devices are suitable for high-speed optical communication systems requiring broad spectral operation.