Self-injection locking efficiency of a UV Fabry-Perot laser diode

Area of Science:

• Optics and Photonics
• Materials Science
• Semiconductor Lasers

Background:

• Gallium nitride (GaN) laser diodes are crucial for various applications.
• Whispering gallery mode (WGM) resonators offer high quality factors (Q-factors) for precise light manipulation.
• Self-injection locking can enhance laser performance but requires careful control.

Purpose of the Study:

• To investigate the performance of a GaN Fabry-Perot laser diode.
• To achieve narrow-linewidth laser emission via self-injection locking.
• To explore the influence of frequency detuning on the locking dynamics.

Main Methods:

• Utilizing a 370 nm GaN Fabry-Perot laser diode.
• Employing a high-Q factor magnesium fluoride (MgF2) WGM resonator for self-injection locking.
• Systematically varying the frequency detuning between the laser cavity and resonator modes.

Main Results:

• Demonstrated strong dependence of the locking state on frequency detuning.
• Achieved monochromatic laser emission with a linewidth below 100 kHz.
• Measured resonator Q-factors exceeding 10^9 in the locked regime.

Conclusions:

• Self-injection locking to a high-Q WGM resonator is an effective method for narrowing laser linewidth.
• Precise frequency detuning is critical for optimizing the laser-resonator interaction.
• The demonstrated sub-100 kHz linewidth and ultra-high Q-factor open possibilities for advanced photonic applications.