Control of light emission by diamond nanoantennas

One of the main motivations for the development of dielectric nanophotonics is the ability to control light on nanoscale through excitation of both electric and magnetic Mie-type resonances. In particular, control of optical... [ view full abstract ]

One of the main motivations for the development of dielectric nanophotonics is the ability to control light on nanoscale through excitation of both electric and magnetic Mie-type resonances. In particular, control of optical emission from active centers can be achieved by modifying the environment of emitters. This can be achieved, for example, by placing them in a vicinity of a nanoantenna. Passive dielectric nanoantennas, in the form of nanoparticles of various shapes, are able to increase emission intensity, accelerate spontaneous emission rate and control the radiative pattern. It is however more efficient to place the emitter inside a dielectric nanoantenna itself, since the emitter inside a dielectric antenna can couple to the optical modes more effectively. Such coupling modifies electromagnetic emission and influences the spontaneous emission rate of emitters. One of the actively studied emitters is a nitrogen-vacancy (NV) center, which is a defect in a diamond. Diamond itself is an excellent optical material with a refractive index close to 2.4. This suggests that we can modify the emission of an NV-center by shaping the host diamond itself in the form of a dielectric nanoantenna.

Here we study nanodiamonds of sizes from (0.3x0.3) μm to (1,5x2) μm, fabricated by milling diamond films, which are grown by plasma-enhanced chemical vapor deposition. NV centers are incorporated during PECVD film growing. Nanoparticles are characterized using scanning electron microscopy, Raman spectroscopy, dark-field scattering and time correlated single photon counting methods.

We show experimentally that Mie-type resonances in nanodiamonds with NV centers lead to the twofold decrease of emission lifetime. In particular, the resonances of large diamond nanoantennas affect photoluminescence properties of NV centers providing acceleration of the emission. In contrast, subwavelength nanoparticles provide fivefold decrease of spontaneous emission rate. We show that the observed phenomena are in a good agreement with theoretical calculations based on Mie theory. We predict that further enhancement of the emission rate can be achieved by precise control of the NV center position within the nanoantennas.

Demonstrated results pave the road for further developments of active nanophotonics towards creation of single photon sources controlled by dielectric nanoantennas.