Ultracompact directional optical nanoantennas are rapidly gaining popularity yet still challenging tasks to construct at the nanoscale. Here, we experimentally demonstrate unidirectional emission from a fluorescent nanodiamond coupled with a single gold nanorod. Different configurations of the assembled hybrid nanostructures were realized via stepby-step atomic force microscope nanomanipulation. The emission patterns can be controlled by adjusting the configurations, i.e., the gold nanorod orientation and separation with respect to the nanodiamond. Numerical simulation results reveal that the unidirectional emission can be ascribed to the interference between the electromagnetic fields produced by the dipolelike source and the out-of-phase dipole induced in the gold nanorod. The proposed hybrid nanostructures remarkably exhibit highly unidirectional emission even when the emitter is positioned up to 50 nm away from the nanorod antenna and present a broad working spectral bandwidth of ß200 nm. The distinct features of this hybrid structure suggest potential applications for novel nanoscale light sources, sensing, and quantum information.

Directional side scattering of light by individual gold nanoparticles (AuNPs) trimers assembled by the atomic force microscope (AFM) nanomanipulation method is investigated in experiment and theory. The AFM nanomanipulation approach brings an active way to construct ultracompact and effective optical nanoantennas. Different configurations of the trimers are constructed in situ via AFM nanomanipulation. Unidirectional side scattering of light by a single trimer is demonstrated with a broad response bandwidth over 400 nm and directivity up to ß7.8 dB in experiments. The near-field plasmon coupling of the AuNPs is simulated with the 3D finite-difference time-domain method and the far-field radiation patterns are calculated by employing near-field-to-far-field transformation methods. The calculated results are in agreement with the experiments qualitatively. The physical origin is revealed intuitively by employing a simple phenomenological "two-dipole" model. The unidirectional light scattering is due to the interference between multiple plasmonic resonance modes of the trimers. The study contributes to the understanding of the optical response of complex nanostructures and optimizing nanoantenna performances for practical applications, e.g. increasing the detection efficiency of surface-enhanced spectroscopy.

Self-healing technology promises a generation of innovation in cross-cutting subjects ranging from electronic skins, to wearable electronics, to point-of-care biomedical sensing modules. Recently, scientists have successfully pulled off significant advances in self-healing components including sensors, energy devices, transistors, and even integrated circuits. Lasers, one of the most important light sources, integrated with autonomous self-healability should be endowed with more functionalities and opportunities; however, the study of self-healing lasers is absent in all published reports. Here, the soft and self-healable random laser (SSRL) is presented. The SSRL can not only endure extreme external strain but also withstand several cutting/healing test cycles. Particularly, the damaged SSRL enables its functionality to be restored within just few minutes without the need of additional energy, chemical/electrical agents, or other healing stimuli, truly exhibiting a supple yet robust laser prototype. It is believed that SSRL can serve as a vital building block for next-generation laser technology as well as follow-on self-healing optoelectronics.

Spontaneous emission modulated by a hybrid plasmonic nanoantenna has been investigated by employing finite-difference time-domain method. The hybrid nanoantenna configurations constituted by a gap hot-spot and of a plasmonic corrugated grating and a metal reflector sandwiching a SiO2 thin layer which appears promising for high spontaneous emission enhancement devices. Simulation assays show that the coupling between the gap-antenna and plasmonic corrugations reaches an ultra-high near-field enhancement factor in the excitation process. Moreover, concerning the emission process, the corrugations concentrate the far-field radiated power within a tiny angular volume, offering unprecedented collection efficiency. In the past decades, many kinds of optical antennas have been proposed and optimized to enhance single molecule detection. However, the excitation enhancement effect for single individual or dimmer plasmonic nanostructure is limited due to intrinsic nonradiative decay of the nanoparticle plasmon and quantum tunneling effect. The proposed hybrid configuration overwhelms the enhancement limit of single individual plasmonic structure. The findings provide an insight into spontaneous emission high enhancement through integrating the functions of different metallic nanostructures.