Whispering gallery mode lasing in optically isolated III-nitride nanorings

Area of Science:

• Materials Science
• Optoelectronics
• Nanotechnology

Background:

• Whispering gallery resonant modes in nanostructures are crucial for photonic devices.
• Minimizing optical coupling to the substrate is essential for enhancing light confinement within resonant cavities.
• III-nitride materials offer unique optoelectronic properties for light emission applications.

Purpose of the Study:

• To demonstrate the fabrication of III-nitride nanorings.
• To investigate methods for maximizing optical confinement in nanoring cavities.
• To achieve optically pumped lasing in III-nitride nanorings at room temperature.

Main Methods:

• Fabrication of III-nitride nanorings using hybrid-nanosphere-lithography.
• Employing laser lift-off processes for material transfer.
• Utilizing an interfacial metallic layer to eliminate substrate optical coupling.
• Characterization of optical properties and lasing performance.

Main Results:

• Successful fabrication of III-nitride nanorings with a tapered cross-sectional profile.
• Elimination of substrate optical coupling, leading to enhanced optical confinement.
• Observation of optically pumped lasing at room temperature with a dominant peak at 421.5 nm.
• Achieved threshold energy density of approximately 6.5 mJ/cm².
• Identified etch-induced sidewall roughness as a cause for light scattering and mode splitting.

Conclusions:

• The demonstrated fabrication technique effectively produces III-nitride nanorings with enhanced optical confinement.
• The nanorings exhibit efficient room-temperature lasing, indicating potential for photonic applications.
• Sidewall roughness presents a challenge that needs to be addressed for improved device performance and confinement.