Sodium metals for single emitter strong coupling:Alternative plasmonic candidates beyond noble metals

This work provides a theoretical investigation into the strong coupling between a single quantum emitter(QE)and the surface plasmons of sodium metals in two representative plasmonic systems,i.e.,the semi-infinite metal-dielectric interface and the metal nanoparticles(NPs)of monomer/dimer configuration.In both configurations,sodium metals exhibit distinctly stronger coupling strength and lower optical loss in the optical region than their noble metal counterparts,demonstrating the ideal candidate characteristics for single-molecule-level strong couplings with distinctly facile operation conditions.Our results provide new insights into extreme light-matter interactions with potential applications in quantum information,optical sensors,quantum chemistry,etc.

Deterministic assembly of single optical cavity formed by gold dimensional DNA origami

Controllable strong interactions between a nanocavity and a single emitter is important to manipulating optical emission in a nanophotonic system but challenging to achieve.Herein a three-dimensional DNA origami,named as DNA rack(DR)is proposed and demonstrated to deterministically and precisely assemble single emitters within ultra-small plasmonic nanocavities formed by closely coupled gold nanorods(AuNRs).Uniquely,the DR is in a saddle shape,with two tubular grooves that geometrically allow a snug fit and linearly align two AuNRs with a bending angle <10°.It also includes a spacer at the saddle point to maintain the gap between AuNRs as small as 2-3 nm,forming a nanocavity estimated to be 20 nm^(3) and an experimentally measured O factor of 7.3.A DNA docking strand is designed at the spacer to position a single fluorescent emitter at nanometer accuracy within the cavity.Using Cy5 as a model emitter,a -30-fold fluorescence enhancement and a significantly reduced emission lifetime(from 1.6 ns to 670 ps)were experimentally verified,confirming significant emitter-cavity interactions.This DR-templated assembly method is capable of fitting AuNRs of variable length-to-width aspect ratios to form anisotropic nanocavities and deterministically incorporate different single emitters,thus enabling flexible design of both cavity resonance and emission wavelengths to tailor light-matter interactions at nanometer scale.

Design of 20 W fiber-coupled green laser diode by Zemax

We represent a design of a 20 W, fiber-coupled diode laser module based on 26 single emitters at 520 nm. The module can produce more than 20 W output power from a standard fiber with core diameter of 400 Hm and numerical aperture （NA） of 0.22. To achieve a 20 W laser beam, the spatial beam combination and polarization beam combination by polarization beam splitter are used to combine output of 26 single emitters into a single beam, and then an aspheric lens is used to couple the combined beam into an optical fiber. The simulation shows that the total coupling efficiency is more than 95%.

Color centers in wide-bandgap semiconductors for subdiffraction imaging:a review

Solid-state atomic-sized color centers in wide-band-gap semiconductors,such as diamond,silicon carbide,and hexagonal boron nitride,are important platforms for quantum technologies,specifically for single-photon sources and quantum sensing.One of the emerging applications of these quantum emitters is subdiffraction imaging.This capability is provided by the specific photophysical properties of color centers,such as high dipole moments,photostability,and a variety of spectral ranges of the emitters with associated optical and microwave control of their quantum states.We review applications of color centers in traditional super-resolution microscopy and quantum imaging methods,and compare relative performance.The current state and perspectives of their applications in biomedical,chemistry,and material science imaging are outlined.