Watt-Level, Narrow-Linewidth, Tunable Green Semiconductor Laser with External-Cavity Synchronous-Locking Technique

Area of Science:

• Optics and Photonics
• Semiconductor Lasers
• Materials Science

Background:

• Gallium Nitride (GaN) semiconductor lasers excel at blue wavelengths but face challenges in green wavelengths (>500 nm) due to the 'green gap'.
• Achieving narrow-linewidth and high-power output in green GaN lasers remains a significant technological hurdle.

Purpose of the Study:

• To demonstrate a watt-level, narrow-linewidth, tunable green semiconductor laser.
• To overcome the limitations imposed by the 'green gap' in GaN laser technology.

Main Methods:

• Employed an external-cavity synchronous-locking technique.
• Utilized two green edge-emitting laser diodes (LDs), beam-shaping optics, and a visible-wavelength diffraction grating.
• Synchronously locked the two LDs leveraging their similar spectral and spatial characteristics.

Main Results:

• Achieved a sharply narrowed 3dB-linewidth from 4 nm to 0.06 nm through synchronous locking.
• Demonstrated tunability of the locked wavelength from 512.2 nm to 520.2 nm.
• Reached a maximum output power of 1.53 W at 518 nm with a 0.15 nm linewidth.

Conclusions:

• Successfully developed the first external-cavity synchronous-locking green semiconductor laser with watt-level output power.
• The demonstrated technique effectively narrows linewidth and enhances output power for green lasers.
• This breakthrough offers a promising solution for high-performance green laser applications.