Photoluminescence lifetime engineering via organic resonant films with molecular aggregates.

Manipulating the spontaneous emission rate of fluorophores is vital in creating bright incoherent illumination for optical sensing and imaging, as well as fast single-photon sources for quantum technology applications. This can be done via increasing the Purcell effect by using non-monolithic optical nanocavities; however, achieving the desired performance is challenging due to difficulties in fabrication, precise positioning, and frequency tuning of cavity-emitter coupling. Here, we demonstrate a simple approach to achieve a wavelength-dependent photoluminescence (PL) lifetime modification using monolithic organic molecular aggregates films.

Metamaterial-Assisted Illumination Nanoscopy with Exceptional Axial Resolution.

Recent advancements in optical metamaterials have opened new possibilities in the exciting field of super-resolution microscopies. The far-field metamaterial-assisted illumination nanoscopies (MAINs) have, very recently, enhanced the lateral resolution to one-fifteenth of the optical wavelength. However, the axial localization accuracy of fluorophores in the MAINs remains rarely explored.

Visualization of the optical spin Hall effect in out-of-plane refraction.

The traditional law of refraction defines the incidence plane as the plane including the incident beam wavevector and the surface normal vector at the interface of two different optical media. The optical spin Hall effect (OSHE) refers to the spin-dependent transverse shift of the refracted beam perpendicular to the incidence plane. In this Letter, we demonstrate that OSHE in out-of-plane refraction can be detected and visualized in the far-field, even at small and normal incidence angles.

Directive emission from polymeric fluorophore with epsilon-near-zero squaraine molecular film.

Enhanced directionality of photoluminescence emission has attracted attention due to its diverse application areas ranging from single-photon sources to fluorescence sensing and bio-imaging. Utilization of null phase advance in epsilon-near-zero (ENZ) medium is an important scheme to achieve the directive emission. Despite various designs proposed for ENZ-based directive emission, most of the ENZ mediums are restricted to subwavelength structures of metallic plasmonics or inorganic dielectrics.

Fluorescence engineering in metamaterial-assisted super-resolution localization microscope.

Single-molecule localization microscopies have gained much attention for their efficient realization of a sub-diffraction-limit imaging with the resolution down to the 10-nm range. In contrast to conventional localization microscopes, which rely on particular fluorescent probes in specific conditions, metamaterial-assisted super-resolution microscopies can be implemented with any fluorescent dye under general conditions. Here, we present a systematic study of fluorescence engineering in metamaterial assisted localization microscopy by using cyclic group metasurfaces coated with a fluorescent film.

Hyperbolic material enhanced scattering nanoscopy for label-free super-resolution imaging.

Fluorescence super-resolution microscopy has, over the last two decades, been extensively developed to access deep-subwavelength nanoscales optically. Label-free super-resolution technologies however have only achieved a slight improvement compared to the diffraction limit. In this context, we demonstrate a label-free imaging method, i.

Ultrathin Layered Hyperbolic Metamaterial-Assisted Illumination Nanoscopy.

Metamaterial-assisted illumination nanoscopy (MAIN) has been proven to be a promising approach for super-resolution microscopy with up to a 7-fold improvement in imaging resolution. Further resolution enhancement is possible in principle, however, has not yet been demonstrated due to the lack of high-quality ultrathin layered hyperbolic metamaterials (HMMs) used in the MAIN. Here, we fabricate a low-loss composite HMM consisting of high-quality bilayers of Al-doped Ag and MgO with a nominal thickness of 2.

Effect of the electron donating group on the excited-state electronic nature and epsilon-near-zero properties of curcuminoid-borondifluoride dyes.

Epsilon-near-zero (ENZ) properties have been reported in organic molecular films. In particular, cyanine and squaraine films have been shown to exhibit ENZ properties in the visible spectral region with a strong 3 order nonlinear optical response near the ENZ spectral region. Noting both cyanine and squaraine belong to the polymethine family, a series of six curcuminoid borondifluoride (Curc) derivatives were developed to examine whether such a polymethine character is positively correlated with the ENZ property of the organic films.

Organic Hyperbolic Material Assisted Illumination Nanoscopy.

Resolution capability of the linear structured illumination microscopy (SIM) plays a key role in its applications in physics, medicine, biology, and life science. Many advanced methodologies have been developed to extend the resolution of structured illumination by using subdiffraction-limited optical excitation patterns. However, obtaining SIM images with a resolution beyond 40 nm at visible frequency remains as an insurmountable obstacle due to the intrinsic limitation of spatial frequency bandwidth of the involved materials and the complexity of the illumination system.

Metamaterial assisted illumination nanoscopy via random super-resolution speckles.

Structured illumination microscopy (SIM) is one of the most powerful and versatile optical super-resolution techniques. Compared with other super-resolution methods, SIM has shown its unique advantages in wide-field imaging with high temporal resolution and low photon damage. However, traditional SIM only has about 2 times spatial resolution improvement compared to the diffraction limit.

Imaging of Cell Morphology Changes via Metamaterial-Assisted Photobleaching Microscopy.

Determining the axial position of an emitter with nanoscale precision is critical to a fundamental imaging methodology. While there are many advanced optical techniques being applied to high-resolution imaging, high-axial-resolution topography imaging of living cells is particularly challenging. Here, we present an application of metamaterial-assisted photobleaching microscopy (MAPM) with high-axial resolution to characterize morphological properties of living cells.

Unprecedented Fluorophore Photostability Enabled by Low-Loss Organic Hyperbolic Materials.

The dynamics of photons in fluorescent molecules plays a key role in fluorescence imaging, optical sensing, organic photovoltaics, and displays. Photobleaching is an irreversible photodegradation process of fluorophores, representing a fundamental limitation in relevant optical applications. Chemical reagents are used to suppress the photobleaching rate but with exceptionally high specificity for each type of fluorophore.

Metamaterial-Assisted Photobleaching Microscopy with Nanometer Scale Axial Resolution.

The past two decades have witnessed a dramatic progress in the development of novel super-resolution fluorescence microscopy technologies. Here, we report a new fluorescence imaging method, called metamaterial-assisted photobleaching microscopy (MAPM), which possesses a nanometer-scale axial resolution and is suitable for broadband operation across the entire visible spectrum. The photobleaching kinetics of fluorophores can be greatly modified via a separation-dependent energy transfer process to a nearby metamaterial.

Low-Loss Organic Hyperbolic Materials in the Visible Spectral Range: A Joint Experimental and First-Principles Study.

Hyperbolic media strengthen numerous attractive applications in optics such as super-resolution imaging, enhanced spontaneous emission, and nanoscale waveguiding. Natural hyperbolic materials exist at visible frequencies; however, implementations of these materials suffer substantial compromises resulting from the high loss in the currently available candidates. Here, the first experimental and theoretical investigation of regioregular poly(3-alkylthiophenes) (rr-P3ATs), a naturally low-loss organic hyperbolic material (OHM) in the visible frequency range, is shown.

Nanoscale optical pulse limiter enabled by refractory metallic quantum wells.

The past several decades have witnessed rapid development of high-intensity, ultrashort pulse lasers, enabling deeper laboratory investigation of nonlinear optics, plasma physics, and quantum science and technology than previously possible. Naturally, with their increasing use, the risk of accidental damage to optical detection systems rises commensurately. Thus, various optical limiting mechanisms and devices have been proposed.

Imaging of Nanoscale Light Confinement in Plasmonic Nanoantennas by Brownian Optical Microscopy.

The strongly enhanced and confined subwavelength optical fields near plasmonic nanoantennas have been extensively studied not only for the fundamental understanding of light-matter interactions at the nanoscale but also for their emerging practical application in enhanced second harmonic generation, improved inelastic electron tunneling, harvesting solar energy, and photocatalysis. However, owing to the deep subwavelength nature of plasmonic field confinement, conventional optical imaging techniques are incapable of characterizing the optical performance of these plasmonic nanoantennas. Here, we demonstrate super-resolution imaging of ∼20 nm optical field confinement by monitoring randomly moving dye molecules near plasmonic nanoantennas.

Blue-Shifting Intramolecular Charge Transfer Emission by Nonlocal Effect of Hyperbolic Metamaterials.

Metallic nanostructures permit controlling various photophysical processes by coupling photons with plasmonic oscillation of electrons confined in the tailored nanostructures. One example is hyperbolic metamaterial (HMM) leading to an enhanced spontaneous emission rate of emitters located nearby. Noting that emission in organic molecules is from either π-π* or intramolecular charge-transfer (ICT) states, we address here how HMM modifies ICT emission spectral features by comparing them with a spectral shift dependent on the local polarity of the medium.

Strong Light Confinement in Metal-Coated Si Nanopillars: Interplay of Plasmonic Effects and Geometric Resonance.

We investigated the influence of metal coating on the optical characteristics of Si nanopillar (NP) arrays with and without thin metal layers coated on the sample surface. The reflection dips of the metal-coated arrays were much broader and more pronounced than those of the bare arrays. The coated metal layers consisted of two parts-the metal disks on the Si NP top and the holey metal backreflectors on the Si substrate.

Electro-optic switching in metamaterial by liquid crystal.

Electro-optic switching of reflection and refraction is experimentally demonstrated in metasurface liquid crystal cell. Negative metasurface is fabricated by focused-ion-beam milling, and twisted nematic cells are constructed with complementary double-split ring resonator and V-shape slot antenna metasurface. By application of an external voltage, electro-optic switchings are achieved in reflection and refraction.