Coupling Emission from Single Localized Defects in Two-Dimensional Semiconductor to Surface Plasmon Polaritons

Area of Science:

• Quantum optics and photonics
• Materials science and nanotechnology

Background:

• Efficient coupling of atom-like emitters to surface plasmons is crucial for developing optical nonlinearity, essential for quantum information processing and quantum networks.
• Achieving strong coupling requires precise nanometer-scale positioning of emitters near plasmonic structures, which presents a significant fabrication challenge.

Purpose of the Study:

• To demonstrate a method for self-aligning single localized defects in a tungsten diselenide (WSe2) monolayer to the surface plasmon mode of a silver nanowire.
• To achieve efficient coupling between two-dimensional semiconductor defects and plasmonic nanostructures.

Main Methods:

• Utilized a silver nanowire to induce a strain gradient on a WSe2 monolayer in the overlapping region.
• This strain gradient facilitated the formation of localized defect emission sites intrinsically positioned close to the surface plasmon mode.
• Measured the coupling efficiency from the defect emitter into the silver nanowire's plasmonic mode.

Main Results:

• Successfully demonstrated the self-alignment of single localized defects in WSe2 to silver nanowire surface plasmons.
• Measured an average coupling efficiency with a lower bound of 26% ± 11% from the emitter to the plasmonic mode.
• The self-alignment mechanism ensures proximity between the emitter and the plasmonic field.

Conclusions:

• This technique provides a viable pathway for realizing efficient coupling between plasmonic nanostructures and localized emitters in two-dimensional semiconductors.
• The self-alignment approach overcomes the challenge of precise nanometer-scale positioning, paving the way for practical quantum devices.