Cavity Confinement Research Articles

Effects of Enzyme-Ligand Interactions on the Photoisomerization of a Light-Regulated Chemotherapeutic Drug.

Molecular photoswitches permit using light to control protein activity with high spatiotemporal resolutions, thereby alleviating the side effects of conventional chemotherapy. However, due to the challenges in probing ultrafast photoisomerization reactions in biological environments, it remains elusive how the protein influences the photochemistry of the photoswitches, which hampers the rational design of light-regulated therapeutics. To overcome this challenge, we employed first-principles nonadiabatic dynamics simulations to characterize the photodynamics of the phototrexate (PTX), a recently developed photoswitchable anticancer chemotherapeutic that reversibly inhibits its target enzyme dihydrofolate reductase (DHFR). Our simulations show that the protein environment impedes the trans to cis photoisomerization of the PTX. The confinement in the ligand-binding cavity slows down the isomerization kinetics and quantum yield of the photoswitch by reshaping its conical intersection, increasing its excited-state free-energy barrier and quenching its local density fluctuations. Also, the protein environment results in a suboptimal binding mode of the photoproduct that needs to undergo large structural rearrangement to effectively inhibit the enzyme. Therefore, we predict that the PTX's trans → cis photoisomerization in solution precedes its binding with the protein, despite the favorable binding energy of the trans isomer. Our findings highlight the importance of the protein environment on the photochemical reactions of the molecular photoswitches. As such, our work represents an important step toward the rational design of light-regulated drugs in photopharmacology.

Parameter optimization of laser-induced breakdown bauxite spectra based on cavity confinement

Parameter optimization of laser-induced breakdown bauxite spectra based on cavity confinement

Analysis of Ba Content in Soil Based on Cavity Confinement LIBS Combined with Multivariate Regression

Analysis of Ba Content in Soil Based on Cavity Confinement LIBS Combined with Multivariate Regression

Cavity confinement in defect-based honeycomb photonic crystals and the design of waveguide–cavity Fano-coupler for dielectric loss sensing

Honeycomb photonic crystal (PhCs) also known as photonic graphene exhibits salient features such as common complete photonic bandgap, topological states, and degrees of freedom to manipulate local density of states for efficient light–matter interactions. In this work, we report the cavity confinement offered by the six different point defect geometries of honeycomb PhCs. It is found that the reported point defect geometries are capable of supporting high confinement with low effective mode area of the order of 10−4 m2. To make use of this cavity confinement, a Fano-coupler is designed based on waveguide–cavity (WG-C) interactions in honeycomb PhC. The transmission/reflection profiles of a WG-C geometry shows typical Fano resonances with the quality factor of the order of 104. Comparing square and triangular PhCs, honeycomb WG-C shows a relatively stable Fano-lineshape resonance for a variation in imaginary part of the dielectric permittivity (ɛr′′) of an unknown dielectric material loaded at the center of the cavity from 0 to 0.01. The proposed WG-C Fano-coupler is suitable for dielectric loss sensing over a conventional cavity perturbation method, in which Fano resonance is sustained with Q factor variation of 25,805 to 2431 for ɛr′′ variation from 0 to 0.01, respectively. Due to the nature of PhC cavity decay dynamics, two different linear sensitive regimes with the dielectric loss sensitivity of 96.901/ɛr′′ (for ɛr′′=0 to 0.005) and 26.911/ɛr′′ (for ɛr′′=0.005 to 0.01) are observed. We anticipate that the cavity confinement and Fano-interactions reported in honeycomb PhCs might be useful not only to explore sensing elements but also for unraveling light–matter interactions in cavity quantum electrodynamics, quantum optics and lasing systems.

Optical dressing of the electronic response of two-dimensional semiconductors in quantum and classical descriptions of cavity electrodynamics

We study quantum effects of the vacuum light-matter interaction in materials embedded in optical cavities. We focus on the electronic response of a two-dimensional semiconductor placed inside a planar cavity. By using a diagrammatic expansion of the electron-photon interaction, we describe signatures of light-matter hybridization characterized by large asymmetric shifts of the spectral weight at resonant frequencies. We follow the evolution of the light dressing from the cavity to the free-space limit. In the cavity limit, light-matter hybridization results in a modification of the optical gap with sizable spectral weight appearing below the bare gap edge. In the limit of large cavities, we find a residual redistribution of spectral weight which becomes independent of the distance between the two mirrors. We show that the photon dressing of the electronic response can be fully explained by using a classical description of light. The classical description is found to hold up to a strong coupling regime of the light-matter interaction highlighted by the large modification of the photon spectra with respect to the empty cavity. We show that, despite the strong coupling, quantum corrections are negligibly small and weakly dependent on the cavity confinement. As a consequence, in contrast to the optical gap, the single-particle electronic band gap is not sensibly modified by strong coupling. Our results show that quantum corrections are dominated by off-resonant photon modes at high energy. As such, cavity confinement can hardly be seen as a knob to control the quantum effects of the light-matter interaction in vacuum.

Room-temperature continuous-wave vertical-cavity surface-emitting lasers based on 2D layered organic–inorganic hybrid perovskites

Two-dimensional (2D) layered lead halide perovskites with large exciton binding energies, efficient radiative recombination, and outstanding environmental stability are regarded as supreme candidates for realizing highly compact and ultralow threshold lasers. However, continuous-wave (CW) pumped lasing of 2D lead halide perovskites, as the precondition for the electrically pumped lasing, is still challenging. Here, we tackled this challenge by demonstrating lasing emission in phenylethylammonium lead iodide [(PEA)2PbI4] embedded in a vertical microcavity under continuous pumping at room temperature. The millimeter-sized (PEA)2PbI4 single crystal was obtained from a two-step seed-growth method, showing high crystallization, excellent thermal stability, and outstanding optical properties. We used the exfoliated (PEA)2PbI4 thin flake as the gain medium to construct a vertical-cavity surface-emitting laser (VCSEL), showing robust single-mode CW lasing operation with an ultra-low threshold of 5.7 W cm−2 at room temperature, attributed to strong optical confinement in the high-Q cavity. Our findings provide a strategy to design and fabricate solution-based 2D perovskite VCSELs and mark a significant step toward the next-generation of coherent light sources.

Nonsuspended optomechanical crystal cavities using As2S3 chalcogenide glass

An optomechanical crystal cavity with nonsuspended structure using As 2 S 3 material is proposed. The principle of mode confinement in the nonsuspended cavity is analyzed, and two different types of optical and acoustic defect modes are calculated through appropriate design of the cavity structure. An optomechanical coupling rate of 82.3 kHz is obtained in the proposed cavity, and the designed acoustic frequency is 3.44 GHz. The acoustic mode coupling between two nonsuspended optomechanical crystal cavities is also demonstrated, showing that the proposed cavity structure has great potential for realizing further optomechanical applications in multicavity systems.

Wide spectrum multi-sub-band modulation of excitons and defect state emission simultaneously in surface oxidized CdS micro/nano-wires

Strong optical confinement and light–matter interaction within semiconductor nanostructures are crucial to modulate the emission property. A fundamental understanding of these interesting phenomena is important to scientific and industrial communities. In this paper, we synthesized the surface oxidized CdS micro/nano-wires by post-oxidation of CdS micro/nano-wires at 475 °C and investigated systematically their novel emission properties. Scanning electron microscopy, energy dispersive x-ray spectrometry, and Raman spectroscopy confirmed the formation of the oxidized surface without changing the structure and morphology of CdS micro/nano-wires greatly. In situ micro-photoluminescence showed the continuous modulation of multi-sub-band emission of both near bandgap and defect state simultaneously with an ultra-broad spectrum range from 490 nm to 750 nm. According to the excitation wavelength-, excitation power-, and temperature-dependent PL spectra, the sub-band near bandgap emission originated from strong light–matter interaction such as photon–exciton coupling, while the whispering gallery mode (WGM) micro-cavity played an important role in the sub-band emission of the defect state. The spatial-resolved mapping of emission modes confirmed the sub-band near bandgap and defect WGM micro-cavity emission from the core and oxidized surface of CdS micro-wires, respectively. The multi-exponential lifetime dynamics further indicated the complex recombination process of both near bandgap and defect state emission. These results are different from the one-step synthesized CdS@CdO core/shell micro-wires and reveal an interesting exciton–photon coupling with enhanced optical cavity confinement in the post-treated CdS micro/nano-wires, representing the rational tailoring of surface/interface relevant properties to control the light emission for application in nanophotonic devices.

Quantum Electrodynamic Control of Matter: Cavity-Enhanced Ferroelectric Phase Transition

The light-matter interaction can be utilized to qualitatively alter physical properties of materials. Recent theoretical and experimental studies have explored this possibility of controlling matter by light based on driving many-body systems via strong classical electromagnetic radiation, leading to a time-dependent Hamiltonian for electronic or lattice degrees of freedom. To avoid inevitable heating, pump-probe setups with ultrashort laser pulses have so far been used to study transient light-induced modifications in materials. Here, we pursue yet another direction of controlling quantum matter by modifying quantum fluctuations of its electromagnetic environment. In contrast to earlier proposals on light-enhanced electron-electron interactions, we consider a dipolar quantum many-body system embedded in a cavity composed of metal mirrors, and formulate a theoretical framework to manipulate its equilibrium properties on the basis of quantum light-matter interaction. We analyze hybridization of different types of the fundamental excitations, including dipolar phonons, cavity photons, and plasmons in metal mirrors, arising from the cavity confinement in the regime of strong light-matter interaction. This hybridization qualitatively alters the nature of the collective excitations and can be used to selectively control energy-level structures in a wide range of platforms. Most notably, in quantum paraelectrics, we show that the cavity-induced softening of infrared optical phonons enhances the ferroelectric phase in comparison with the bulk materials. Our findings suggest an intriguing possibility of inducing a superradiant-type transition via the light-matter coupling without external pumping. We also discuss possible applications of the cavity-induced modifications in collective excitations to molecular materials and excitonic devices.

Dual CXCR4 and E-Selectin Inhibition (GMI-1359) Rapidly Increases AML Cellular Motility Prior to Intravasation and Vascular Niche Depletion Observed By Intravital Bone Marrow Two-Photon Microscopy

BACKGROUND: Acute myelogenous leukemia (AML) cells that reside in bone marrow (BM) receive a great deal of protection from the cytotoxic effects of therapeutic agents. In contrast, the circulating leukemia cells are typically more chemosensitive compared to those embedded in BM niches. The BM homing of AML cells is mediated by multiple adhesive and chemokinetic interactions including, respectively, by sialylated glycoproteins on the cancer cells binding to E-selectin on the endothelium and by CXCR4-mediated sensing of SDF-1/CXCL12 gradients. Consequently, both E-selectin and CXCR4 inhibitors have been pursued as targets for add-on therapeutic strategies aimed to "mobilize" AML cells out of the BM. A next generation "mobilizing" agent GMI-1359 combines, in one molecular structure, the E-selectin and CXCR4 inhibitory moieties. In a previous study, GMI-1359 markedly reduced leukemia cell adhesion to endothelial cells, leukemia cellularity in BM (Zhang et al., 2016) and it enhanced the survival of cytarabine/daunorubicin therapy in a FLT3-mutated AML model (Zhang et al., 2015). APPROACH: Here, we used intravital 2-photon microscopy of calvarial BM to study the behavioral response of AML cells to the dual CXCR4 and E-selectin inhibition (GMI-1359) in vivo. We used a mTurquoise2 fluorescence-tagged transplantable mouse AML model (characterized by MLL, ENL-FLT3, ITD, p53-/-). To delineate the bone and vascular niches, the syngeneic immune-competent recipient mice harbored cell lineage fluorescence reporter genes such as Col2.3-GFP, hCD2-DsRed and CD11c-EYFP with the bone collagen and blood highlighted by, respectively, second harmonic generation (SHG) and fluorescent dextran. Intravenously infused AML cells (5x10E4) homed to BM where they gradually displaced most endogenous cells. In this experimental system, GMI-1359 or vehicle were infused into the tail vein while recording AML cell motilities in calvarial BM stroma in 3-D over 4 hours. RESULTS: In untreated or control vehicle treated mice, AML cells were slowly motile, migrating with the average velocity of ~2 µm/min. Cellular trajectories were random within the average 400 µm confinement radius corresponding to the size of BM cavities. Most AML cells localized in the vascular niche, defined as within a 50 µm distance to the nearest blood vessel. A minority of AML cells were also present in the proximity to osteoblasts and the bone (i.e. in the bone niche). In contrast, GMI-1359 infusion resulted in a 66% increase of the average speed of cellular motility of AML cells within 20 min and up to 100% increase within 3.5 hours. The motility pattern remained largely random within the bone cavity confinement volume and was concentrated in the vicinity of vasculature. Thereafter, we observed multiple instances of AML cell intravasation into the capillary lumens followed by several minute-long vessel wall attachment and sudden outflow. This cellular dynamics resulted in a substantial, yet structurally biased decrease of BM AML cellularity whereby the vascular niche was emptied preferentially whilst the bone niche remained populated by AML cells. In no case we observed a complete BM depletion of AML cells. Interestingly, as we reported before, a single, CXCR4-only inhibitor caused a protracted (24-48 h) depletion of AML cells in BM without significant cellular motility enhancement. CONCLUSIONS: Our observations reveal an unexpected mechanism of action by a dual E-selectin/CXCR4 inhibitor involving cellular migratory motility enhancement in BM stroma prior to AML cell intravasation. We envisage that, besides the designed blocking of E-selectin and CXCR4 molecules from binding their corresponding ligands, the dual moiety GMI-1359 agent has a capacity to generate motility-enhancing signals in AML cells that single inhibitors do not seem to trigger. Among several mechanisms possible, this action could involve E-selectin and CXCR4 crosslinking by a dual moiety molecular structure or binding avidity enhancement, requiring further investigation. In addition, our results highlight a likely mechanism of AML resistance to therapeutic "mobilization", one that involves cancer cell persistence in the bone/osteoblastic niches. Disclosures Zal: Daiichi-Sankyo: Research Funding; Moleculin Biotech, Inc.: Research Funding. Fogler:GlycoMimetics: Current Employment, Current equity holder in publicly-traded company, Patents & Royalties. Magnani:GlycoMimetics, Inc.: Current Employment, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties. Andreeff:Daiichi-Sankyo; Jazz Pharmaceuticals; Celgene; Amgen; AstraZeneca; 6 Dimensions Capital: Consultancy; Daiichi-Sankyo; Breast Cancer Research Foundation; CPRIT; NIH/NCI; Amgen; AstraZeneca: Research Funding; Amgen: Research Funding; Centre for Drug Research & Development; Cancer UK; NCI-CTEP; German Research Council; Leukemia Lymphoma Foundation (LLS); NCI-RDCRN (Rare Disease Clin Network); CLL Founcdation; BioLineRx; SentiBio; Aptose Biosciences, Inc: Membership on an entity's Board of Directors or advisory committees.

Optimally enhanced optical emission in laser-induced breakdown spectroscopy by combining a cylindrical cavity confinement and Au-Nanoparticles action

In order to study the characteristics of laser-induced breakdown spectroscopy(LIBS), the optimal size of cavity(D = 5 mm, H = 4 mm) was obtained using the aluminum cylindrical cavities with different diameters (from 2 mm to 6 mm)and heights(from 1 mm to 6 mm) in LIBS and the optimal size of Au-NPs(D = 20 nm) was obtained by depositing Au-NPs (10 nm, 20 nm, 30 nm in particle diameter) on the shot of pure copper sample surface that was cleaned by laser. The enhancement factor is about 22.5, 5.4, 34.3 under the confinement of the optimal cavity, the action of the optimal Au-NPs and the combination of the optimal cavity and optimal Au-NPs, respectively. The plasma temperatures, and SNR, were calculated and researched under different conditions. Experiments have shown that cavity confinement can increase the electron temperature of the plasma, while under the Au-NPs action, the electron temperature hardly changes. Compared with zero confinement, Au-NPs action and cavity confinement can all improve the SNR of the plasma spectrum, but the SNR is the best with the combination of the optimal cavity and optimal Au-NPs. The enhancement principle was analyzed by shock wave theory and properties of Au-NPs.

Electro-optic interface for ultrasensitive intracavity electric field measurements at microwave and terahertz frequencies

Electro-optic quantum coherent interfaces map the amplitude and phase of a quantum signal directly to the phase or intensity of a probe beam. At terahertz frequencies, a fundamental challenge is not only to sense such weak signals (due to a weak coupling with a probe in the near-infrared) but also to resolve them in the time domain. Cavity confinement of both light fields can increase the interaction and achieve strong coupling. Using this approach, current realizations are limited to low microwave frequencies. Alternatively, in bulk crystals, electro-optic sampling was shown to reach quantum-level sensitivity of terahertz waves. Yet, the coupling strength was extremely weak. Here, we propose an on-chip architecture that concomitantly provides subcycle temporal resolution and an extreme sensitivity to sense terahertz intracavity fields below 20 V/m. We use guided femtosecond pulses in the near-infrared and a confinement of the terahertz wave to a volume of V T H z ∼ 10 − 9 ( λ T H z / 2 ) 3 in combination with ultraperformant organic molecules ( r 33 = 170 p m / V ) and accomplish a record-high single-photon electro-optic coupling rate of g e o = 2 π × 0.043 G H z , 10,000 times higher than in recent reports of sensing vacuum field fluctuations in bulk media. Via homodyne detection implemented directly on chip, the interaction results into an intensity modulation of the femtosecond pulses. The single-photon cooperativity is C 0 = 1.6 × 10 − 8 , and the multiphoton cooperativity is C = 0.002 at room temperature. We show > --> 70 d B dynamic range in intensity at 500 ms integration under irradiation with a weak coherent terahertz field. Similar devices could be employed in future measurements of quantum states in the terahertz at the standard quantum limit, or for entanglement of subsystems on subcycle temporal scales, such as terahertz and near-infrared quantum bits.

Encapsulation of Azaphosphatranes and Proazaphosphatranes in Confined Spaces.

Proazaphosphatranes (also named Verkade's superbases) and their azaphosphatrane conjugated acids have been recently been shown to be confined in either covalent or self-assembled molecular cages, or immobilized in nanopores of hybrid materials. The encapsulation of these phosphorus moieties turns out to strongly affect both their acid-base, catalytic, and recognition properties. The thermodynamics and kinetics of the proton transfer as well as the selectivity and catalytic activities of Verkade's superbases were strongly changed upon their confinement in a hemicryptophane cavity. Moreover, self-assembled cages, including azaphosphatrane moieties, were found to display remarkable anion recognition properties in water. In this Minireview, these new aspects of the chemistry of aza- and proaza-phosphatranes are presented, in order to highlight the great potential of such an approach.

Influence of cavity and magnetic confinements on the signal enhancement and plasma parameters of laser-induced Mg and Ti plasmas

AbstractIn this study, we have spectroscopically investigated the plasma generated by a Q-switched Nd:YAG laser operating at its fundamental wavelength of 1064 nm focused on magnesium (Mg) and titanium (Ti) target samples in the air under atmospheric pressure. We employed circular cavities of radii (2.5, 3.0, and 3.5 mm) and a square cavity to investigate the cavity confinement effect on the spectral emission intensities of the plasmas. We observed that the circular cavity of radius 2.5 mm had the maximum signal enhancement, and this can be attributed to the compression of the plasma and reheating by the reflected shock waves. The maximum enhancement factor of the Mg I-518.4 nm line was reached at approximately 3.8, 3.4, and 2.8 with a circular cavity of radius 2.5, 3.0, and 3.5 mm, respectively, at a delay time of 350 ns and a laser energy of 350 mJ. By applying varying external magnetic fields (0.47, 0.62, 0.91, and 1.23 T) across the generated plasma, the plasma parameters such as electron temperature and number density have been investigated. From our results, we observed that the radius of the cavity had a tremendous effect on the enhancement of the emission signal intensities. We also found that the increase in the electron temperature and the number density can be attributed to the increase in the applied magnetic field and the laser energy. From our calculations, the value of β, which was less than 1 for all the cases, confirms that there was a plasma confinement at the presence of the magnetic field.

Decoration of ultrathin porous zeolitic imidazolate frameworks on zinc–cobalt layered double hydroxide nanosheet arrays for ultrahigh-performance supercapacitors

In this work, ultra-thin zeolitic imidazolate frameworks (ZIFs) layers are coated on Zn–Co layered double hydroxide (LDH) nanosheet electrodes by chemical vapor deposition. The ZIF-coated Zn–Co LDH nanosheets are revealed to present excellent electrochemical performances (specific capacitance of 2068 F g−1 at scan rate of 1 A g−1, and retention ratio of 92.6% after 10,000 cycles), which are much higher than those of the untreated ones (specific capacitance of 1444 F g−1 at 1 A g−1, and retention ratio of 63.6% after 10,000 cycles). The enhanced electrochemical performance may be attributed to the cavity confinement effect and more active sites exposed by the rough Zn–Co LDH nanosheets coated with ZIFs. Meanwhile, the ZIFs with porous structure and ultra-high specific surface area could promote the redox reaction on the surface of the Zn–Co LDH nanosheets by electrolyte ions storing and adsorbing during the electrochemical process. The surface-coated ZIFs can effectively avoid unnecessary electrochemical reaction between the electrolyte and the electrode material during electrochemical cycling, avoiding irreversible dissolution during cycling. Furthermore, the Zn–Co-130-ZIFs-10h//NC-950 device delivers a higher energy density of 42.5 Wh kg−1 at a power density of 424 W kg−1.

Spectral characteristics of laser-induced plasma under the combination of Au-nanoparticles and cavity confinement

To enhance the emission spectrum intensity of laser-induced plasma, a method of combining cavity-enhanced laser-induced breakdown spectroscopy (LIBS) with nanoparticles-enhanced LIBS (NELIBS) was proposed. In this paper, the brass with Au-nanoparticles deposited on the surface is placed under the condition of cavity confinement and cavity-free confinement, and the differences between various performances are analyzed. The experimental results show that spectral line enhancement effect is the best when cavity confinement diameter is 5 mm. When cavity-enhanced LIBS is combined with NELIBS, the plasma intensity is effectively enhanced, and the enhancement factor is up to 20.24 (Cu I 515.4 nm); signal-to-noise ratio (SNR) is improved significantly, and it reaches 337.21 when pulse energy is 60 mJ. Electron temperature is in the range of 12,040–14,260 K and electron density is increased, the ability of detect trace elements is greatly improved.

Signal Intensity Enhancement by Cavity Confinement of Laser-Produced Plasma

The effect of hemispherical cavity confinement on the laser-generated plasma plume has been studied and revealing a fivefold signal intensity enhancement in the spectra of copper. The plasma temperature ( $T$ ) and electron density ( $N_{e}$ ) with and without cavity confinements have been determined. The plasma parameters ( $T$ and $N_{e}$ ) in the cavity confinement configuration remain the same for the first few microseconds and thereafter decay exponentially. The trend of constant plasma parameters for the first few microseconds is attributed to the competition of two processes; compression of the plasma plume by the reflected shock waves and cooling of the plasma plume by losing its kinetic energy due to the collision of the ambient gases. The signal intensity enhancement can be attributed to the reheating or compression of plasma plume by the reflected shock waves.

Numerical study of metallic semiconductor nanolasers with double-concave cavity structures

<sec>Metallic semiconductor nanolaser, as an ultra-small light source, has been increasingly attractive to researchers in last decade. It can have wide potential applications such as in photonic integrated circuits, on-chip interconnect, optical communications,etc. One obstacle to miniaturization of the laser size is that the loss increases rapidly with the cavity volume decreasing. In previous studies, a type of Fabry-Perot cavity with capsule-shaped structure was investigated and demonstrated both numerically and experimentally, showing that its cavity loss is reduced dramatically in contrast to the scenario of conventional rectangular cavities. However, when the cavity size is reduced down to nanoscale, capsule-shaped structure surfers high loss. To overcome this difficulty, in this paper, a novel type of double-concave cavity structure for metallic semiconductor nanolaser in a 1.55 μm wavelength range is proposed and numerically studied. The proposed structure consists of InGaAs/InP waveguide structure encapsulated by metallic clad, and has a cylindrical reflection end face and concave curved sidewalls. </sec><sec>The cylindrical reflection end face can push the resonant mode into the cavity center and reduce the optical field overlap with metallic sidewalls, which can reduce the metallic loss. The curved-sidewalls topologically reduce the electric field component perpendicular to the sidewalls, and thus reducing the plasmonic loss. By optimizing the waist width of the double-concave cavity structure, the radiation loss can be effectively reduced, resulting in the improvement of cavity quality factor and the decrease of threshold current. Finite-difference time-domain simulations are conducted to investigate the properties of the proposed cavity structures such as resonant mode distribution, cavity quality factor, confinement factor, threshold gain and threshold current in this paper. The numerical results show that the double-concave cavity laser with cavity volume as small as 0.258 <i>λ</i><sup>3</sup> increases 24.8% of cavity quality factor and reduces 67.5% of threshold current, compared with the conventional capsule-shaped one, demonstrating an effective improvement of metallic nanolaser. With those advantages, the proposed structure can be used for realizing the ultra-small metallic semiconductor nanolasers and relevant applications.</sec>

Network topology and cavity confinement-controlled diastereoselectivity in cyclopropanation reactions catalyzed by porphyrin-based MOFs

In this work, we show that the stereoselectivity of a reaction can be controlled by directing groups of substrates, by network topology and by local cavity confinement of metal–organic framework (MOF) catalysts.

Bloch Surface Waves Fabry- Pérot Nanocavity

We demonstrate the first cavity confinement of Bloch surface waves in the fundamental mode of a Fabry–Pérot cavity. The cavity consists of two distributed Bragg mirrors separated by a spacer of dimensions smaller than the wavelength (633nm). The cavity mode exhibits quality factor of 400. This quality factor is the highest recorded thus far for a subwavelength optical surface waves cavity.