Spectral Tuning of Perovskite Laser via Microheaters.

Perovskites have recently brought significant advances to active nanophotonics, offering a unique combination of gain and phase-change properties for tunable light-emitting devices. However, current wavelength-tunable devices often rely on tuning mechanisms or device architectures that lead to slow modulation or bulky setups. Here, we demonstrate a compact tunable microlaser with electrical microheaters integrated beneath a perovskite metasurface, enabling efficient heating and rapid phase transitions.

Establishing an end-to-end workflow for SNSPD fabrication and characterization.

The outstanding performance of superconducting nanowire single-photon detectors (SNSPDs) has expanded their application areas from quantum technologies to astronomy, space communication, imaging, and LiDAR. As a result, there has been a surge in demand for these devices, that commercial products cannot readily meet. Consequently, more research and development efforts are being directed towards establishing in-house SNSPD manufacturing, leveraging existing nano-fabrication capabilities that can be customized and fine-tuned for specific needs.

Electrically Generated Exciton Polaritons with Spin On-Demand.

Generation and manipulation of exciton polaritons with controllable spin could deeply impact spintronic applications, quantum simulations, and quantum information processing, but is inherently challenging due to the charge neutrality of the polariton and the device complexity it requires. Here, electrical generation of spin-polarized exciton polaritons in a monolithic dielectric perovskite metasurface embedded in a light-emitting transistor is demonstrated. A finely tailored interplay of in- and out-of-plane symmetry breaking of the metasurface allows to lift the spin degeneracy through the polaritonic Rashba effect, yielding high spin purity with normalized Stokes parameter of S ≈ 0.

Directional Emission from Electrically Injected Exciton-Polaritons in Perovskite Metasurfaces.

We present a new approach to achieving strong coupling between electrically injected excitons and photonic bound states in the continuum of a dielectric metasurface. Here a high-finesse metasurface cavity is monolithically patterned in the channel of a perovskite light-emitting transistor to induce a large Rabi splitting of ∼200 meV and more than 50-fold enhancement of the polaritonic emission compared to the intrinsic excitonic emission of the perovskite film. Moreover, the directionality of polaritonic electroluminescence can be dynamically tuned by varying the source-drain bias, which induces an asymmetric distribution of exciton population within the transistor channel.

Topological Insulator Metamaterials.

Confinement of electromagnetic fields at the subwavelength scale via metamaterial paradigms is an established method to engineer light-matter interaction in most common material systems, from insulators to semiconductors and from metals to superconductors. In recent years, this approach has been extended to the realm of topological materials, providing a new avenue to access nontrivial features of their electronic band structure. In this review, we survey various topological material classes from a photonics standpoint, including crystal growth and lithographic structuring methods.

Perovskite quantum dot one-dimensional topological laser.

Various topological laser concepts have recently enabled the demonstration of robust light-emitting devices that are immune to structural deformations and tolerant to fabrication imperfections. Current realizations of photonic cavities with topological boundaries are often limited by outcoupling issues or poor directionality and require complex design and fabrication that hinder operation at small wavelengths. Here we propose a topological cavity design based on interface states between two one-dimensional photonic crystals with distinct Zak phases.

Counting and mapping of subwavelength nanoparticles from a single shot scattering pattern.

Particle counting is of critical importance for nanotechnology, environmental monitoring, pharmaceutical, food and semiconductor industries. Here we introduce a super-resolution single-shot optical method for counting and mapping positions of subwavelength particles on a surface. The method is based on the deep learning analysis of the intensity profile of the coherent light scattered on the group of particles.

Resonant Enhancement of Polymer-Cell Optostimulation by a Plasmonic Metasurface.

Organic semiconductors have shown great potential as efficient bioelectronic materials. Specifically, photovoltaic polymers such as the workhorse poly(thiophene) derivatives, when stimulated with visible light, can depolarize neurons and generate action potentials, an effect that has been also employed for rescuing vision in blind rats. In this context, however, the coupling of such materials with optically resonant structures to enhance those photodriven biological effects is still in its infancy.

Phase-Change Perovskite Microlaser with Tunable Polarization Vortex.

Metasurfaces supporting optical bound states in the continuum (BICs) are emerging as simple and compact optical cavities to realize polarization-vortex lasers. The winding of the polarization around the singularity defines topological charges which are generally set by the cavity design and cannot be altered without changing geometrical parameters. Here, a subwavelength-thin phase-change halide perovskite BIC metasurface functioning as a tunable polarization vortex microlaser is demonstrated.

Polarization-Tunable Perovskite Light-Emitting Metatransistor.

Emerging immersive visual communication technologies require light sources with complex functionality for dynamic control of polarization, directivity, wavefront, spectrum, and intensity of light. Currently, this is mostly achieved by free space bulk optic elements, limiting the adoption of these technologies. Flat optics based on artificially structured metasurfaces that operate at the sub-wavelength scale are a viable solution, however, their integration into electrically driven devices remains challenging.

Quantum Interference of Resonance Fluorescence from Germanium-Vacancy Color Centers in Diamond.

Resonance fluorescence from a quantum emitter is an ideal source to extract indistinguishable photons. By using the cross-polarization to suppress the laser scattering, we observed resonance fluorescence from GeV color centers in diamond at cryogenic temperature. The Fourier-transform-limited line width emission with /2 ∼ 0.

Phase-change perovskite metasurfaces for dynamic color tuning.

Halide perovskite metasurfaces are attracting increasing interest for applications in light-emitting and display technologies. To access the wide range of colors required for these applications, the main mechanism exploited thus far has been chemical engineering of the perovskite compounds - this constitutes a significant limitation for the dynamic switching of optical response desirable in actual devices. Here we demonstrate polarization-dependent, dynamic control of structural color and emission wavelength in an all-dielectric phase-change halide perovskite nanograting metasurface, by temperature tuning.

Perovskite metasurfaces with large superstructural chirality.

Recent attempts to synthesize hybrid perovskites with large chirality have been hampered by large size mismatch and weak interaction between their structure and the wavelength of light. Here we adopt a planar nanostructure design to overcome these limitations and realize all-dielectric perovskite metasurfaces with giant superstructural chirality. We identify a direct spectral correspondence between the near- and the far- field chirality, and tune the electric and magnetic multipole moments of the resonant chiral metamolecules to obtain large anisotropy factor of 0.

Optical Rashba Effect in a Light-Emitting Perovskite Metasurface.

The Rashba effect, i.e., the splitting of electronic spin-polarized bands in the momentum space of a crystal with broken inversion symmetry, has enabled the realization of spin-orbitronic devices, in which spins are manipulated by spin-orbit coupling.

Non-invasive super-resolution imaging through dynamic scattering media.

Super-resolution imaging has been revolutionizing technical analysis in various fields from biological to physical sciences. However, many objects are hidden by strongly scattering media such as biological tissues that scramble light paths, create speckle patterns and hinder object's visualization, let alone super-resolution imaging. Here, we demonstrate non-invasive super-resolution imaging through scattering media based on a stochastic optical scattering localization imaging (SOSLI) technique.

Metamaterial Enhancement of Metal-Halide Perovskite Luminescence.

Metal-halide perovskites are rapidly emerging as solution-processable optical materials for light-emitting applications. Here, we adopt a plasmonic metamaterial approach to enhance photoluminescence emission and extraction of methylammonium lead iodide (MAPbI) thin films based on the Purcell effect. We show that hybridization of the active metal-halide film with resonant nanoscale sized slits carved into a gold film can yield more than 1 order of magnitude enhancement of luminescence intensity and nearly 3-fold reduction of luminescence lifetime corresponding to a Purcell enhancement factor of more than 300.

Exciton-Enabled Meta-Optics in Two-Dimensional Transition Metal Dichalcogenides.

Optical wavefront engineering has been rapidly developing in fundamentals from phase accumulation in the optical path to the electromagnetic resonances of confined nanomodes in optical metasurfaces. However, the amplitude modulation of light has limited approaches that usually originate from the ohmic loss and absorptive dissipation of materials. Here, an atomically thin photon-sieve platform made of MoS multilayers is demonstrated for high-quality optical nanodevices, assisted fundamentally by strong excitonic resonances at the band-nesting region of MoS.

Phase stabilization of a coherent fiber network by single-photon counting.

Coherent optical fiber networks are extremely sensitive to thermal, mechanical, and acoustic noise, which requires elaborate schemes of phase stabilization with dedicated auxiliary lasers, multiplexers, and photodetectors. This is particularly demanding in quantum networks operating at the single-photon level. Here, we propose a simple method of phase stabilization based on single-photon counting and apply it to quantum fiber networks implementing single-photon interference on a lossless beamsplitter and coherent perfect absorption on a metamaterial absorber.

Perovskite-Ion Beam Interactions: Toward Controllable Light Emission and Lasing.

Achieving controllable coherent and incoherent light sources is crucial to meet the requests of the constantly developing integrated optics, which, however, remains challenging for the existing semiconductor materials and techniques. All-inorganic lead halide perovskites (ILHPs) are emerging as the promising semiconductors, featuring the defect-tolerant nature and tunable band gap. Herein, an experimental design, based on the interaction between ILHPs and energetic ions, for achieving controllable light emitters and microlasers is reported.

Room temperature solid-state quantum emitters in the telecom range.

On-demand, single-photon emitters (SPEs) play a key role across a broad range of quantum technologies. In quantum networks and quantum key distribution protocols, where photons are used as flying qubits, telecom wavelength operation is preferred because of the reduced fiber loss. However, despite the tremendous efforts to develop various triggered SPE platforms, a robust source of triggered SPEs operating at room temperature and the telecom wavelength is still missing.

Tailoring optical metamaterials to tune the atom-surface Casimir-Polder interaction.

Metamaterials are fascinating tools that can structure not only surface plasmons and electromagnetic waves but also electromagnetic vacuum fluctuations. The possibility of shaping the quantum vacuum is a powerful concept that ultimately allows engineering the interaction between macroscopic surfaces and quantum emitters such as atoms, molecules, or quantum dots. The long-range atom-surface interaction, known as Casimir-Polder interaction, is of fundamental importance in quantum electrodynamics but also attracts a significant interest for platforms that interface atoms with nanophotonic devices.

Organometallic Perovskite Metasurfaces.

Organometallic perovskites, solution-processable materials with outstanding optoelectronic properties and high index of refraction, provide a platform for all-dielectric metamaterials operating at visible frequencies. Perovskite metasurfaces with structural coloring tunable across visible frequencies are realized through subwavelength structuring. Moreover, a threefold increase of the luminescence yield and comparable reduction of luminescence decay time are observed.

Atomic Response in the Near-Field of Nanostructured Plasmonic Metamaterial.

We report on reflection spectra of cesium atoms in close vicinity of a nanostructured metallic meta-surface. We show that the hyperfine sub-Doppler spectrum of the 6(2)S1/2-6(2)P3/2 resonance transition at 852 nm is strongly affected by the coupling to the plasmonic resonance of the nanostructure. Fine tuning of dispersion and positions of the atomic lines in the near-field of plasmonic metamaterials could have uses and implications for atom-based metrology, sensing, and the development of atom-on-a-chip devices.

Plasmon-Polaron Coupling in Conjugated Polymer on Infrared Nanoantennas.

We propose and demonstrate a novel type of coupling between polarons in a conjugated polymer and localized surface plasmons in infrared (IR) nanoantennas. The near-field interaction between plasmons and polarons is revealed by polarized photoinduced absorption measurements, probing mid-IR polaron transitions, and infrared-active vibrational modes of the polymer, which directly gauge the density of photogenerated charge carriers. This work proves the possibility of tuning the polaronic properties of organic semiconductors with plasmonic nanostructures.