Harnessing the Diamond-Air Interface as an Efficient Photon Antenna for Solid-State Emitters

Area of Science:

• Quantum optics
• Materials science
• Solid-state physics

Background:

• Extracting photons from diamond defect centers, like nitrogen-vacancy (NV) centers, is difficult due to substrate refractive index.
• High saturation count rates (>2.5 × 10⁵ counts/s) typically necessitate complex nanofabricated optics (e.g., waveguides, solid immersion lenses).

Purpose of the Study:

• Investigate defect center emission from unmodified planar dielectric surfaces.
• Explore alternative methods for efficient photon collection without nanofabrication.
• Develop a novel method for measuring quantum efficiency of shallow defect centers.

Main Methods:

• Quantitative back-focal-plane imaging.
• Analytical modeling of light emission.
• Oil-immersion microscopy for enhanced collection.

Main Results:

• Achieved photon count rates comparable to nanofabricated optics using oil-immersion and unmodified surfaces.
• Identified a dielectric antenna effect enhancing emission into the substrate within a specific angle.
• Quantified back-side collection efficiency, enabling a new quantum efficiency measurement.

Conclusions:

• Oil-immersion optics can achieve high photon extraction rates from defect centers on planar surfaces, rivaling nanofabricated solutions.
• The dielectric antenna effect is key to efficient light redirection for back-side collection.
• The novel quantum efficiency measurement challenges existing values for shallow defect centers.