Single-mode Bragg ring laser diodes.

Area of Science:

• Optoelectronics
• Semiconductor Lasers
• Integrated Photonics

Background:

• Semiconductor ring lasers are crucial for integrated optics.
• Bragg waveguide structures offer unique waveguiding properties but suffer from leaky modes.
• Efficient light confinement and low loss are essential for high-performance ring lasers.

Purpose of the Study:

• To design and fabricate a monolithic semiconductor ring laser utilizing a Bragg waveguide structure.
• To overcome the inherent leaky nature of Bragg waveguide modes.
• To demonstrate a functional ring laser operating in the Bragg mode with enhanced performance.

Main Methods:

• Fabrication of a monolithic semiconductor ring laser with a Bragg waveguide.
• Development of a two-step etching process (shallow-etched coupler, deep-etched bend) to minimize losses.
• Utilizing evanescent coupling via a tangent waveguide for cavity access.

Main Results:

• Demonstrated a ring laser lasing in the Bragg mode with output power >1 mW in continuous wave (CW) operation.
• Achieved a threshold current density of ~2.2 kA/cm² with single longitudinal mode operation.
• Observed broadband phase-matching for nonlinear optical processes, enabling >40 nm self-pumped parametric C-band conversion with 142 %W⁻¹cm⁻² efficiency.

Conclusions:

• The developed Bragg waveguide structure successfully confines light, enabling efficient ring laser operation.
• The two-step etching process effectively reduces losses, improving laser performance.
• The laser's nonlinear properties facilitate broadband parametric conversion, highlighting its potential for optical communications and signal processing.