Phase shift optimization of III/V-on-bulk-Si DFB LD for single-mode stability

Area of Science:

• Semiconductor lasers
• Integrated photonics
• Materials science

Background:

• Distributed feedback (DFB) lasers are crucial for optical communication.
• Achieving stable single-mode operation at high currents remains a challenge.
• III/V-on-Bulk-Si technology offers a pathway for integrating lasers onto silicon platforms.

Purpose of the Study:

• To present a III/V-on-Bulk-Si DFB laser with an optimized long phase shift section.
• To enhance stable single-mode operation significantly.
• To compare its performance against conventional DFB lasers.

Main Methods:

• Design and fabrication of a III/V-on-Bulk-Si DFB laser.
• Optimization of the phase shift section length and sub-wavelength-scale tuning.
• Analysis of single-mode stability up to 20 times the threshold current.
• Side-mode suppression ratio (SMSR) based yield analysis.

Main Results:

• Stable single-mode operation achieved up to 20 times the threshold current.
• Maximized gain difference between fundamental and higher modes through optimized phase shift.
• Superior performance of the long-phase-shifted DFB laser compared to conventional λ/4-phase-shifted designs.
• Demonstrated enhanced mode stability.

Conclusions:

• The optimized long phase shift section is effective in achieving superior single-mode stability in III/V-on-Bulk-Si DFB lasers.
• This design offers a significant improvement over traditional DFB laser structures.
• The findings pave the way for more robust and reliable silicon-integrated photonic devices.