Strongly enhanced photon collection from diamond defect centres under micro-fabricated integrated solid immersion lenses

TL;DR

This paper demonstrates that integrating solid immersion lenses directly into diamond surfaces significantly enhances photon collection efficiency from defect centers, reducing background noise and increasing count rates, with potential for scalable quantum applications.

Contribution

The study introduces a scalable fabrication method for integrated solid immersion lenses in diamond, markedly improving photon collection from defect centers.

Findings

10-fold increase in photon count rate with SILs

3-fold reduction in background emission

Enhanced photon collection efficiency demonstrated

Abstract

The efficiency of collecting photons from optically active defect centres in bulk diamond is greatly reduced by refraction and reflection at the diamond-air interface. We report on the fabrication and measurement of a geometrical solution to the problem; integrated solid immersion lenses (SILs) etched directly into the surface of diamond. An increase of a factor of 10 was observed in the saturated count-rate from a single negatively charged nitrogen-vacancy (NV-) within a 5um diameter SIL compared with NV-s under a planar surface in the same crystal. A factor of 3 reduction in background emission was also observed due to the reduced excitation volume with a SIL present. Such a system is potentially scalable and easily adaptable to other defect centres in bulk diamond.