Whispering-gallery mode lasing from optically free-standing InGaN microdisks.

Area of Science:

• Semiconductor physics
• Optoelectronics
• Materials science

Background:

• Whispering-gallery mode (WGM) resonators are crucial for low-threshold lasers.
• Indium Gallium Nitride (InGaN)/Gallium Nitride (GaN) quantum wells are promising materials for visible light emission.

Purpose of the Study:

• To investigate optically pumped WGM lasing in free-standing InGaN/GaN quantum well microdisks.
• To characterize the lasing properties, including threshold, quality factor, and free spectral range.

Main Methods:

• Fabrication of optically isolated microdisks using microsphere lithography and laser lift-off.
• Optical pumping experiments at room temperature.
• Analysis of lasing modes using simulations and spectral measurements.

Main Results:

• Successful observation of multi-mode WGM lasing in InGaN/GaN microdisks at room temperature.
• Low lasing threshold of approximately 9.06 mJ/cm².
• High quality factor (Q) of ~770 for the dominant mode at 430.2 nm.

Conclusions:

• Optically free-standing InGaN/GaN microdisks are effective WGM resonators for lasing applications.
• The fabrication method provides superior optical confinement, enabling efficient lasing.
• The results pave the way for developing compact and efficient InGaN-based laser devices.