In an article published recently in the journal Nano Letters, a hybridized plasmon probe made of a fiber taper and silver nanowire (Ag NW) was utilized to selectively alter the radiation characteristics of single photon emitters (SPEs) with variably aligned polarization.
Study: Near-Field Modulation of Differently Oriented Single Photon Emitters with A Plasmonic Probe. Image Credit: wacomka/Shutterstock.com
The Significance of Single Photon Emitters
Single photon emitters (SPEs) have been the focus of extensive research for decades, with the goal of creating bright and pure sources as the foundation of expandable quantum nanoscale photonic systems. Solid-phase SPEs play a critical role in quantum computers, quantum simulations, quantum encrypted networking, quantum walks, and highly precise estimations.
Several solid-state SPEs, like quantum dots (QDs), nitrogen-vacancy (NV) color centers in diamond, and point defects in thin sheets of semiconductive transition-metal dichalcogenides (TMDs), have been produced.
Manipulation of SPEs is critical for emerging quantum data processing, and several ways have been suggested. A recent study, for example, revealed improved emissions via emitters coupled with microscale cavities; another employed a resonance nanoscale antenna to reduce the lifespan of hexagon boron nitride SPEs, while another used spherical gold nanoparticles in immediate proximity to quantum emissions to produce light improvement.
Modulation of Light with Plasmon Structures
Control of SPE irradiation is challenging due to an imbalance in between efficient modal sizes of the SPE's fixed dipole moment and traditional photonic technologies, even with microscale or nanoscale optical instruments like dielectric waveguides. A much reduced modal size on the subwavelength level is necessary to boost the pairing intensity among the SPEs and photons.
Surface plasmon polaritons (SPPs) considerably boost the pairing by restricting the optical mode to nanometric range, resulting in increased SPE output. Generally, though, it stays within the weaker coupling range due to SPP degradation.
SPP-photon pairing has emerged as a significant area of study for tip improvement, optical gadget manufacturing, sensing, and other applications. Furthermore, it is well established that the intensity of the pairing is largely dependent on the overlapping of the electrical field vectors among emitters and SPP mode. This means that the linkage is highly responsive to photon polarization, which is an essential characteristic that may be used to encrypt quantum data.
Several investigations have been conducted on the polarization-reliant regulation of luminescence using plasmon devices. A previous study, for instance, discovered that the polarization of the activation laser and the orientation of Ag NWs were connected to the light amplification of CdSe nanostructures.
Unfortunately, there is a lack of research in the literature on the polarization dependency of the linkage among SPPs and SPEs. The effort in this study is focused on investigating the substantial polarization-reliance of consistent modulation for SPEs in greater depth.
Important Findings of the Study
In this study, the team used a plasmon probe incorporated with a hanging Ag NW clinging to a fiber taper to locally adjust the lifespan of SPEs with various configurations in the near field region.
When the probe was inserted into the SPE's near field region, the emission speed of the activated phase in the SPE may be controlled effectively, as shown by variations in lifespan. This variation is substantially influenced by the polarized alignment of the SPEs.
The emission lifespan of dipoles having out-of-plane polarization elements, like CdSe quantum dots, was considerably reduced while the PL was increased by changing the plasmon probe. As a result of shifting the probe horizontally, it may be possible to actively increase or decrease the lifespan of in-plane configurations such as hBN defect SPEs.
The scientists also detailed the physical process of lifespan modifications using computational simulations and hypotheses, which might give a unique perspective into the creation of nanoscale photonic systems and embedded circuits.
The practical findings also support previous computational simulations and conceptual analyses. This research also opens up exciting possibilities for new quantum photonic sources. Brighter SPEs, for instance, could be generated at ambient temperatures using this technology, and the optical properties of a specific SPE with nanoscale dimensions may be modified locally.
Liu, X.-J., Wu, Y.-K. et al. (2022). Near-Field Modulation of Differently Oriented Single Photon Emitters with A Plasmonic Probe. Nano Letters. Available at: https://pubs.acs.org/doi/10.1021/acs.nanolett.1c04409