Directional amplified spontaneous emissions from Ag nanohole array with high diffraction orders.

Area of Science:

• Photonics
• Plasmonics
• Nanotechnology

Background:

• Surface plasmon polaritons (Bloch-SPPs) on metallic nanostructures enable nanoscale light control.
• Bloch-SPPs offer light confinement, near-field enhancement, and surface propagation.
• Metallic nanohole arrays are key platforms for studying plasmonic phenomena.

Purpose of the Study:

• To experimentally demonstrate a plasmonic device for highly directional visible light emission.
• To investigate the role of Bloch-SPPs in nanohole arrays for light amplification.
• To explore applications in tunable lasers and fluorescence detection.

Main Methods:

• Fabrication of a plasmonic cavity using a 100 nm silver film on a porous alumina array.
• Utilizing four-level rhodamine 6G as the gain medium.
• Characterization of amplified spontaneous emission (ASE) properties.

Main Results:

• Observation of directional, five-fold enhanced ASE with polarization dependence.
• Achieved a low lasing threshold of 199.9 W/cm².
• Demonstrated strong local electric fields and high Purcell factors at nanohole edges due to Bloch-SPPs.

Conclusions:

• The developed plasmonic device enables efficient and directional light emission in the visible spectrum.
• The 2D periodic nanohole array provides optical feedback for amplified spontaneous emission.
• This technology holds promise for tunable lasers, multimode lasers, and sensitive fluorescence detection.