Sensing operations based on hexagonal GaN microdisks acting as whispering-gallery mode optical microcavities

Area of Science:

• Materials Science
• Nanotechnology
• Photonics

Background:

• Gallium nitride (GaN) microdisks function as optical microcavities.
• Whispering-gallery modes (WGMs) in microcavities are sensitive to ambient refractive index changes.

Purpose of the Study:

• To demonstrate sensing capabilities of hexagonal GaN microdisks.
• To explore the potential of GaN microdisks as optical microbiosensors.

Main Methods:

• Room temperature photoluminescence measurements.
• Utilizing hexagonal GaN microdisks (approx. 1.5 μm side length) as whispering-gallery mode (WGM) optical microcavities.
• Monitoring shifts in lasing wavelength due to changes in ambient conditions (isopropanol/o-xylene mixtures, sucrose solutions).

Main Results:

• Sensing operation demonstrated using hexagonal GaN microdisks.
• Lasing wavelength shifts observed with varying isopropanol/o-xylene ratios and sucrose concentrations.
• Detection of tiny waterborne particles achieved with the microdisk.

Conclusions:

• Hexagonal GaN microdisks exhibit WGM-based sensing capabilities.
• These microdisks show promise for developing optical microbiosensors for localized detection (1-2 μm radius).