Evolution of multi-mode operation in vertical-external-cavity surface-emitting lasers

Area of Science:

• Laser Physics
• Optoelectronics
• Photonics

Background:

• Vertical-external-cavity surface-emitting lasers (VECSELs) exhibit complex emission dynamics.
• Understanding longitudinal mode behavior is crucial for VECSEL applications.

Purpose of the Study:

• Investigate longitudinal multi-mode emission in VECSELs.
• Analyze single- and two-color emission regimes.
• Determine factors influencing emission bandwidth and mode operation.

Main Methods:

• Employed single-shot streak camera measurements.
• Utilized interferometric measurement techniques.
• Operated VECSELs in etalon (two-color) and free-running (single-color) configurations.

Main Results:

• Observed a sharp increase in emission bandwidth near the laser threshold.
• Monitored the transition between single- and multi-mode longitudinal operation.
• Found stable two-color operation correlates with a high number of longitudinal modes per color.

Conclusions:

• Longitudinal mode behavior in VECSELs is sensitive to pump power and resonator losses.
• The number of oscillating longitudinal modes is a key factor for stable multi-color emission in VECSELs.