We have introduced a breakthrough concept, presenting superdirective nanoantennas that utilize higher-order magnetic multipole moments in subwavelength dielectric nanoparticles. Our small Si nanosphere with a notch achieves exceptional directivity, enabling precise radiation control at the nanoscale. The beam radiation direction is highly sensitive to source position variations within the notch, resulting in efficient radiation steering. Comparing to a similar plasmonic nanoantenna, our dielectric nanoantenna exhibits superior directivity, reduced losses, and a remarkable radiation efficiency of up to 70%, advancing nanoantenna design and performance.
The Purcell effect, which refers to the modification of the spontaneous emission rate of a quantum emitter in the presence of a resonant cavity, holds significant implications. Interestingly, this effect has a classical counterpart: the emission rate change caused by the environment. By considering a small antenna tuned to a resonance as an oscillator with radiative losses, we can model and measure the impact of the environment on its radiation, similar to a quantum emitter. Leveraging this analogous behavior, we have developed a powerful and concise approach to calculate the Purcell factors of various systems across different frequency ranges, encompassing both electric and magnetic Purcell factors. Our approach is exemplified through a comprehensive equivalent scheme, enabling the presentation of the Purcell factor as the continuous radiation of a small antenna in the presence of an electromagnetic environment.
We have achieved remarkable results in enhancing the performance of microdisk lasers. Our innovative technique involves utilizing a platinum-carbon plasmonic wire nanoantenna grown via electron-beam assisted deposition along the cavity's side wall. This enables us to enhance laser emission and modify its directionality towards the vertical axis. Our findings demonstrate a 20-fold increase in dominant mode intensity, a 24 dB increment in side mode suppression, and a Q-factor of over 3 × 10^4. This approach holds great promise for practical applications in telecommunication technologies and biosensing.
Krasnok, A. E., Maloshtan, A., Chigrin, D. N., Kivshar, Y. S. & Belov, P. A. Enhanced emission extraction and selective excitation of NV centers with all-dielectric nanoantennas. Laser Photon. Rev. 9, 385–391 (2015).
A groundbreaking method to enhance the excitation and readout processes of isolated negatively charged nitrogen-vacancy (NV) centers has been developed. By utilizing all-dielectric nanoantennas, the emission rate and extraction efficiency of photoluminescence signals from individual NV centers in diamond nanoparticles on dielectric substrates can be significantly boosted. This innovative approach offers exceptional directivity, a substantial Purcell factor, and effective beam steering, enabling efficient far-field initialization and readout of multiple NV centers even when they are separated by subwavelength distances.
we have explored high-index dielectric nanoparticles as a robust platform for advancing nonlinear nanophotonics. Our study introduces a versatile dielectric nanoantenna composed of a chain of silicon particles excited by a dipole emitter. This nanoantenna exhibits slow group-velocity guided modes, associated with the Van Hove singularity, offering a high Purcell factor of several hundred. By leveraging the sensitivity to nanoparticle permittivity, we have demonstrated precise tuning of the nanoantenna using ultrafast laser pumping, even at low intensities (25 GW/cm2). The laser pumping induces significant variations in the nanoantenna radiation patterns and Purcell factor. Additionally, we have successfully launched unidirectional surface-plasmon polaritons within the nanoantenna on an Ag substrate through EHP excitation..
We have conducted a thorough theoretical investigation on a tunable Yagi-Uda nanoantenna comprised of core-shell nanoparticles (Ag-Ge). Our results reveal a hybrid Yagi-Uda nanoantenna with dual operating regimes, showcasing two resonances within each nanoparticle. The nanoantenna operates conventionally at low frequencies, emitting highly directive radiation forward. At higher frequencies, a unique operating regime emerges, driven by the core-shell nanoparticles' magneto-electric response and van Hove singularity excitation. This regime exhibits exceptional emission properties within a narrow frequency range, including high directivity and Purcell factor. Our analysis highlights the potential for flexible and dynamic tuning of this hybrid nanoantenna's emission pattern by exciting an electron-hole plasma with a 100 fs pump pulse, even at low peak intensities (~200 MW/cm²). This groundbreaking discovery enables precise control and tailoring of nanoantenna emission characteristics.
We have achieved enhanced and optimized performance of high-index dielectric (Si) nanoantennas, resulting in efficient light outcoupling from InAs/Ga(Al)As quantum dot (QD) microdisk lasers. Through thorough experimental analysis using confocal optical microscopy, we investigated the spatial distribution of emitted light from optically pumped QD microdisk lasers. By precisely positioning a single Si spherical nanoantenna on the microdisk's top surface, we demonstrated the ability to selectively extract specific laser modes, achieving a remarkable 23-fold increase in emission intensity at the nanoantenna's location. This enhancement preserved the high quality factor of the resonator and exhibited a fourfold improvement in the overall emission intensity of the microdisk laser. Our findings highlight the immense potential of Si nanoantennas in enhancing QD microdisk lasers, opening new avenues for highly efficient and versatile photonic devices.
In the emerging field of all-dielectric nanophotonics, we explore the potential of dielectric nanoresonators and 2D transition metal dichalcogenides (2D TMDCs) for enhancing light-matter interactions. By analyzing bright exciton photoluminescence (PL) amplification in WS2, MoS2, WSe2, and MoSe2, coupled with silicon nanoparticles' Mie resonances, we identify optimal parameters for maximal PL enhancement. Through meticulous optimization, we demonstrate a remarkable one hundred-fold increase in PL intensity from 2D TMDCs using all-dielectric Si nanoantennas. These findings hold great promise for high-efficiency 2D TMDC-based optoelectronic, nanophotonic, and quantum optical devices.