Wide-waveguide high-power low-RIN single-mode distributed feedback laser diodes for optical communication

Area of Science:

• Photonics and Laser Technology
• Semiconductor Devices
• Optical Communications

Background:

• Distributed feedback (DFB) lasers are crucial for optical communication.
• Achieving high power, single-mode operation, and low noise simultaneously in DFB lasers remains a challenge.
• Existing designs often face trade-offs between output power, mode stability, and optical losses.

Purpose of the Study:

• To design and fabricate a high-power, single-mode DFB laser with low relative intensity noise (RIN).
• To investigate the impact of a dual-waveguide structure on laser performance.
• To assess the suitability of the developed laser for optical communication applications.

Main Methods:

• Utilized a dual-waveguide structure to modify lateral optical confinement in the ridge waveguide.
• Fabricated an 8-µm-wide, 800-µm-long DFB laser.
• Characterized laser performance including output power, RIN, side-mode suppression ratio (SMSR), wavelength tunability, linewidth, and relaxation oscillation frequency.

Main Results:

• Achieved an output power exceeding 170 mW.
• Demonstrated relative intensity noise (RIN) below -157 dB/Hz.
• Obtained a side-mode suppression ratio (SMSR) over 55 dB.
• Exhibited 8.6 nm wavelength tunability over a temperature range of -10°C to 60°C (0.12 nm/K).
• Measured a linewidth of approximately 250 kHz at 100 mW output power.
• Observed a relaxation oscillation frequency around 8 GHz.

Conclusions:

• The dual-waveguide structure effectively reduces optical losses and maintains single-mode stability.
• The fabricated DFB laser exhibits excellent performance characteristics: high power, low RIN, and high SMSR.
• The laser's properties make it a promising candidate for advanced optical communication systems.