Simultaneous edge and surface stimulated emission from AlGaN-based deep ultraviolet laser bars

Area of Science:

• Materials Science
• Optoelectronics
• Semiconductor Physics

Background:

• AlGaN-based deep ultraviolet (DUV) lasers are crucial for various applications.
• Understanding stimulated emission mechanisms is key to improving DUV laser performance.

Purpose of the Study:

• To investigate simultaneous edge stimulated emission (ESE) and surface stimulated emission (SSE) in AlGaN-based DUV laser bars.
• To explore the impact of n-cladding layer growth temperature on ESE and SSE characteristics.
• To establish a correlation between SSE and ESE for optimizing DUV laser performance.

Main Methods:

• Optical pumping of AlGaN-based DUV laser bars.
• Measurement of ESE and SSE properties, including threshold and linewidth.
• Analysis of surface morphology and defect concentration (C_N-related) in the n-AlGaN cladding layer.

Main Results:

• Simultaneous ESE and SSE were achieved in DUV laser bars at high optical pumping power densities.
• SSE properties were independent of cavity length, suggesting vertical optical resonance.
• Increasing growth temperature of the n-cladding layer significantly reduced SSE onset threshold and linewidth.
• ESE lasing threshold and linewidth were also reduced with optimized growth temperature.
• Improved lasing performance correlated with smoother surface morphology and lower C_N-related defects.

Conclusions:

• SSE originates from vertical optical resonance within epilayers.
• Optimizing n-cladding layer growth temperature enhances DUV laser performance by reducing internal loss.
• The positive correlation between SSE and ESE provides an efficient method to assess and improve DUV laser performance using SSE from unprocessed wafers.