With the development of metasurfaces and the improvement of manufacturing technology, it is important and imperative to design novel metasurfaces that can flexibly manipulate terahertz (THz) waves. In this paper, a multifunctional metasurface (MFMS) based on graphene and photosensitive silicon (Si) is proposed, which integrates three functions: broadband absorption, broadband linear and circular polarization

We report the first measurements of phase-matching angles for second-harmonic generation, sum- and difference- frequency generations performed over the transparency range of the uniaxial α-GeO2 crystal. A simultaneous fit of these data provided dispersion equations. The optical damage threshold and the magnitude of the nonlinear coefficient d11 are also determined. We found |$d_{11}^{GeO2}({0.67\;{\rm{\mu

We present the results of a comprehensive spectroscopic investigation pertaining to laser potential evaluation of the 3-micron Dy3+ mid-IR transition in the low-maximum phonon energy host barium fluoride (BaF2). This investigation involved absorption, fluorescence, and decay time measurements, recorded for a range of temperatures. Laser-relevant parameters such as absorption and stimulated-emission

This work analyzes (and looks to control) the manifestations of loss in polymer composites in the THz spectrum due to material crystallinity, material charge carrier densities, and suboptimal fabrication. Polymer composites are fabricated from a variety of materials and their losses are characterized using THz time-domain spectroscopy. It is found that reduced crystallinity, large free carrier densities

Transient features of graphene oxide (GO), graphene oxide nanoribbon (GOR) and graphene quantum dot (GQD) have been investigated by femtosecond transient absorption (TA) spectroscopy. It is found that for pristine GO and HNO3-/NaOH-treated GO, a hybrid sp2/sp3 state at about 430 nm (∼2.88 eV) always appears. However, this hybrid state becomes less apparent in GOR, and completely disappears in GQD.

Color centers in hexagonal boron nitride (hBN) are presently attracting broad interest as a novel platform for nanoscale sensing and quantum information processing. Unfortunately, their atomic structures remain largely elusive and only a small percentage of the emitters studied thus far have the properties required to serve as optically addressable spin qubits. Here, we use confocal fluorescence microscopy

We have investigated the failure mechanism of organic functional materials and organic light-emitting diodes (OLEDs) by annealing at high temperatures. We found that N,N'-bis(naphthalen-1-yl)-N,N'-bis(phenyl)-benzidine (NPB) doped molybdenum oxide and 1,3,5-tri[(3-pyridyl)-phen-3-yl]benzene doped cesium carbonate can enhance the thermal stability significantly. The former composite film reveals the

This is an introduction to the feature issue of Optical Materials Express on Artificial Intelligence Meets Engineered Photonic Materials.

The laser damage induced by nano-absorbing centers generally results in a local high temperature and pressure environment, leading to denser phases and complex hydrodynamic processes. Here we parameterize the metal-organic framework force field to overcome the notorious unphysical agglomeration at small atomic distance in a Buckingham term. The structure and shock properties of amorphous silica are

Sm3+/Eu3+: YAlO3 (Sm3+/Eu3+: YAP) single crystal with a size of Ф (25-35) mm × (50-60) mm was successfully grown and analyzed. The use of Sm3+ co-doping to enhance Eu3+: 5D0 → 7F2 orange-red emission has been investigated in the YAP crystal for the first time. Compared with the Eu3+ single-doped YAP crystal, the Sm3+/Eu3+ co-doped YAP crystal possessed a larger fluorescence emission cross section (0

This paper determines the stable configuration and electronic structure of Ce-related defects (CeV) in diamonds doped with N, B, and Si impurities using the first-principle method based on density functional theory (DFT) and the Vienna ab-initio simulation package VASP software package. To this end, the zero-phonon line size of the color center of the doped diamond CeV is calculated and the corresponding

Due to the problems of low absorptivity and the narrow bandwidth of existing broadband absorbers, a perfect broadband tunable absorber with high absorptivity based on double-layer graphene is proposed in this study with 99% high absorptivity as the reference standard, and its theoretical analysis is performed. The designed absorber consists of complete graphene, upper dielectric material, patterned

Multiplex coherent anti-stokes Raman scattering (M-CARS) and second harmonic generation (SHG) techniques are used to map the real part of the nonresonant third order nonlinear optical susceptibility and the second order nonlinear optical susceptibility of a thermally microimprinted niobium borophosphate glass. In particular, such bimodal nonlinear imaging is employed in order to precisely evaluate

The refractive index of commonly used 3D printing photosensitive resins were measured across the visible spectrum for s- and p-polarized light for the first time. Commercially available resins (Monoprice Clear and formlabs Clear) and a custom polyethylene glycol diacrylate photopolymer resin was characterized using a critical angle determination method with a Pulfrich-based refractometer setup. The

A promising Nd:YAG single-crystal fiber (SCF) was successfully fabricated by the laser-heated pedestal growth method. The compact passively Q-switched laser has been realized for the first time with a 794 nm laser diode pumping. Pulsed laser performances of this SCF were investigated in detail with a flat-flat resonator. Under the absorbed pump power of 2.50 W, the peak power of 274.24 W was obtained

To achieve a surface-enhanced Raman spectroscopy (SERS) sensor that is easy to make and use, we propose periodic gold nanotrench arrays, which can be fabricated without surface contamination and intricate sensor alignment. Deep and narrow plasmonic nanotrenches for amplifying local electromagnetic fields were reliably generated on a wafer-scale substrate by nanoimprint lithography and two successive

The high-efficiency excitation and dynamic manipulation of the nondiffracting surface plasmon polariton (SPP) beam are important prerequisites for practical applications including the next-generation on-chip devices, near field optical trapping, and micromanipulation. Here we proposed two kinds of high-efficiency coupling and wavelength-dependent nondiffracting SPP beam unidirectional devices, which

Reconfigurable three-dimensional (3D) nanostructures possess additional spatial freedom and rich physical characteristics compared with their two-dimensional (2D) counterparts. Here we demonstrate a facile and automated nano-kirigami method to create the 3D deformed spiral metasurfaces, which can flexibly manipulate optical waves by simply applying external voltages. Through etching Archimedean spirals

Van der Waals materials are expected to meet the miniaturization and integration challenges in photonic integrated circuits (PIC) as active devices for optical communication. Recently, ultralow threshold lasers, ultra-sensitive or large bandwidth photodetectors have been demonstrated on silicon photonics platforms that are compatible with the state-of-the-art CMOS process. Here we summarize the characteristics

Anisotropic plasmonic films are a desirable material for many optoelectronic applications. Here, we propose a method to align silver nanowires (AgNWs) with the help of uniaxial nematic alignment of cellulose nanocrystal (CNC) liquid crystals (LCs) that can preserve their LC orientation in solid film. AgNWs are doped into uniaxial nematic CNC LCs, where AgNWs are oriented parallel to the director of

We propose an all-dielectric metamaterial composed of bi-layered silicon structures orthogonally arranged on the sandwiched silica substrate, which exhibits giant dual-band asymmetric transmission of linearly polarized wave in the near-infrared regime, with one band working for the x-polarization and the other one for y-polarization. The dual-band AT phenomenon is explained by the distributions of

An ultra-thin single band metamaterial (MTM) based perfect absorber with suppressed higher order absorption modes is presented in this paper. The unit cell structure is comprised of square shaped resonant patch whose sides are attached to interdigitally coupled fingers providing strong cell to cell electromagnetic coupling, which is found to have a significant impact in reducing the effect of higher

A standardized hybrid deep-learning model based on a combination of a deep convolutional network and a recurrent neural network is proposed to predict the optical response of metasurfaces considering their shape and all the important dimensional parameters (such as periodicity, height, width, and aspect ratio) simultaneously. It is further used to aid the design procedure of the key components of solar

Mid-infrared photonic integrated circuits (PICs) that combine on-chip light sources with other optical components constitute a key enabler for applications such as chemical sensing, light detection, ranging, and free-space communications. In this paper, we report the monolithic integration of interband cascade lasers emitting at 3.24 µm with passive, high-index-contrast waveguides made of chalcogenide

We present a systematic study of micro-trench resonators for heterogeneous integration with silicon waveguides. We experimentally and numerically demonstrate that the approach is compatible with a large variety of thin film materials and that it does not require specific etching recipe development, thus making it virtually universal. The microresonators are fabricated through in-foundry silicon-on-insulator

Active metamaterials (MTMs) are artificially engineered structures with tunable and exceptional properties that are absent in natural materials. Recently, InGaZnO (IGZO), a widely used semiconductor for large-area and flexible display backplane drivers, has gained interest for active control of MTMs due to its large-area uniformity, ease of thin film deposition, and low cost. In this paper, IGZO Schottky

Photonic molecules (PMs) are of great interest for, e.g., optical filters/sensors or topological and exceptional-point photonics. A key requirement for their versatile application is the tunability of the PM’s coupling strength. This important feature is realized in the here introduced widely and precisely tunable PM on an all-polymeric chip-scale platform. The PM consists of two disk-shaped whispering

Based on the transmission characteristics of surface plasmon polaritons (SPPs) in sub-wavelength structures, this paper proposes a metal-insulator-metal (MIM) waveguide structure composed of a main waveguide with glass (SiO2) branches (WWGB) coupled with an elliptical split-ring resonance cavity (ESRRC). WWGB has a broadband continuous transmission spectrum, while ESRRC has a narrow-band discrete transmission

Broken inversion and time reversal symmetries affect the electromagnetic wave modes supported by continuous media, which in turn governs thermal radiation and enables control of radiative heat, linear momentum, and angular momentum transfer. We identify opportunities for exploring thermal radiation in inversion symmetry- and time reversal symmetry-breaking materials and compare and contrast radiative

This work demonstrates the magnetic field-induced spectral properties of metamaterials incorporating both indium antimonide (InSb) and tungsten (W) in the terahertz (THz) frequency regime. Nanostructure materials, layer thicknesses and surface grating fill factors are modified, impacting light-matter interactions and consequently modifying thermal emission. We describe and validate a method for determining

Further miniaturization of imaging systems is prevented by the prevalent, traditional bulky refractive optics today. Meta-optics have recently generated great interest in the visible wavelength as a replacement for refractive optics thanks to their low weight, small size, and amenability to high-throughput semiconductor manufacturing. Here, we extend these meta-optics to the long-wave infrared (LWIR)

Plasmonic polarization multiplexers are becoming increasingly significant for the development of high-speed plasmonic interconnection with broad bandwidth. Here, we demonstrate that the symmetrical double-groove structure can act as a polarization multiplexer for broadband femtosecond surface plasmon polaritons (SPPs) by investigating the mode distributions with photoemission electron microscopy (PEEM)

A stronger electric field in metal nanostructures can be realized by exciting nanoparticle plasmonic resonances to enhance hot electron generation. One can alter the nanoparticle shape, size, material, and/or the refractive index of the surrounding medium to achieve higher efficiency. Here, we report the nanostructure design that enhances the generation of plasmonic hot electrons from the periodically

Photonic crystals (PhC) represent an important class of silicon photonics components employed as wavelength selective resonators to act as narrow-band mirrors in integrated lasers due to their small footprint, high surface area, and Q-factor/volume ratio that enables efficient confinement of light, required for improved performances of the laser. These properties of PhCs are key for the potential deployment

In this study, a refractive-index guiding single-crystal fiber (SCF) with air–solid cladding was proposed and numerical simulation investigation was carried out. In general, refractive-index guided cladding was constructed through air-holes in the solid material. It resulted in the effective reduction in the number of guided-modes, and the single-mode and few-mode transmission could be realized. The

This research is a study of the photon radiation from the bilayer graphene perturbed by the electromagnetic field. Theoretically, our simulation shows vividly the asymmetry property of such bilayer graphene resulting in the outstanding attribute of the photon emission profiles. The methods employed in our work are a tight-binding model in the many-body system and Fermi’s golden rule. In this work,

Quantum dots are a promising new candidate for use as emissive materials in the next generation of light-emitting diodes for lighting and display applications. One of the key issues in the solution preparation of inverted quantum dot light-emitting diodes (QDLEDs) is making a suitable sandwich structure of hydrophilic and hydrophobic layers. We solved this problem by inserting an ultrathin film of

The IR absorption spectrum of high purity photo-thermo-refractive (PTR) glasses melted under atmosphere containing different concentrations of water is studied. The absorption spectra of the water and glass matrix are separated and deconvoluted to elementary Gaussian bands. The water absorption spectrum includes 11 bands with a maxima at 4320, 3560, 3053, 2897, 2815, 2765, 2525, 2315, 2219, 2150, and

Fused silica glass is a commonly used high-performance material. However, due to the high temperature necessary for its production, manufacturing can also be challenging and costly. An attractive approach is additive manufacturing through laser cladding. Laser cladding of transparent fused silica was achieved using a CO2-laser to locally melt the substrate while injecting a stream of fumed silica glass

This work experimentally demonstrates mid-infrared emittance spectra of dielectric and semi-conductor substrates with and without a germanium–antimony–tellurium (GST) film coating. The film experiences non-volatile phase changes at 140°C and 300°C. Impacts from amorphous, face-centered cubic, and hexagonal close packed phases on spectral emittance are demonstrated within the spectral range from 4 μm

1060 nm continuous-wave and passively Q-switched pulse lasers were demonstrated in a 3.5-mm-thick X-cut Nd:GdPO4 crystal. At an absorbed pump power of 1.91 W, a 1060 nm continuous-wave laser with a maximum output power of 0.72 W and a slope efficiency of 42% was realized. When a Cr4+:YAG saturable absorber with an initial transmission of 85% was used, a passively Q-switched pulse laser with repetition

Single crystal fiber (SCF) lasers have attracted extensive attention recently. In this paper, Tm:SrF2 SCF was successfully grown by the temperature gradient method. With a compact resonator, the acousto-optically Q-switched properties of a diode-pumped Tm:SrF2 SCF laser was investigated first. At the repetition rate of 500 Hz, a highest pulse energy of 1.32 mJ and a narrowest pulse width of 51 ns were

In this work, to the best of our knowledge, the first demonstration of 1047-nm Q-switched mode-locked Nd:YLF cladding waveguide lasers fabricated by femtosecond laser direct writing (FsLDW) is reported. Modulated by Gr-ReS2-Gr heterostructure film, the fabricated waveguide laser delivers laser pulses with a pulse duration of as short as 31 ps at a fundamental repetition rate of up to 9.55 GHz. The

We report on the development of a novel laser crystal with broadband emission properties at ∼2 µm – a Tm3+,Li+-codoped calcium tantalum gallium garnet (Tm:CLTGG). The crystal is grown by the Czochralski method. Its structure (cubic, sp. gr. $Ia\bar{3}d$, a = 12.5158(0) Å) is refined by the Rietveld method. Tm:CLTGG exhibits a relatively high thermal conductivity of 4.33 Wm-1K-1. Raman spectroscopy

Carbon nanohorn dahlia aggregates with a lateral size of hundreds of nanometers and a height of a few nanometers were prepared utilizing commercial carbon nanohorn powder. In the mid-infrared spectral region (@ 2845 nm), the saturable absorption property of the carbon nanohorn was experimentally investigated. It was employed as a saturable absorber in a Er:Lu2O3 laser. Laser pulses with a shortest

The formation of laser-induced periodic surface structures (LIPSS) on Ti thin films, their phase and stoichiometric evolution, as a function of well below ablation threshold laser fluence, and the number of pulses, is investigated. The experiments were carried out in ambient air by using a femtosecond laser at a wavelength of 1030 nm with a pulse duration of 270 fs, operating at a repetition rate of

Smart windows based on VO2 can control the infrared radiation entering the building based on the temperature, however, the visible part of the spectrum is not controlled. Liquid crystal (LC) based privacy windows, on the other hand, control the visibility either with temperature or applied voltage, however, the total transparency remains fixed as the scattering is mainly in the forward direction. To

Cetyltrimethylammonium bromide (CTAB) was employed as an ionic dopant dispersed into a nematic liquid crystal characterized by its negative dielectric anisotropy. The electrohydrodynamic (EHD) effect in liquid crystal cells impregnated with various contents of CTAB was studied by dielectric spectroscopy and the corresponding electro-optical responses of the cells driven by an AC electric field were

Energy squeezing is attractive for its potential applications in electromagnetic (EM) energy harvesting and optical communication. However, due to the Fabry-Perot resonance, only the EM waves with discrete frequencies can be squeezed and, as far as we know, in the previous energy-squeezing devices, stringent requirements of the materials or the geometrical shape are needed. We note that the structures

In this work, we explore inverse designed reconfigurable digital metamaterial structures based on phase change material Sb2Se3 for efficient and compact integrated nanophotonics. An exemplary design of a 1 × 2 optical switch consisting of a 3 µm x 3 µm pixelated domain is demonstrated. We show that: (i) direct optimization of a domain containing only Si and Sb2Se3 pixels does not lead to a high extinction

Typical applications of integrated photonics in the mid-infrared (MIR) are different from near-infrared (telecom) range and, in many instances, they involve chemical sensing through MIR spectroscopy. Such applications necessitate tailored designs of optical waveguides. Both cross-sectional designs and processing methods of MIR waveguides have been a subject of extensive research, where material transparency

In this manuscript, we propose a tunable multifunctional reflection polarization converter based on a graphene sheet, which is decorated by a π-shaped carved-hollow array. Our design can achieve the linear-to-linear (LTL) polarization conversion with 3.58 THz bandwidth and two linear-to-circular (LTC) polarization conversion bands with opposite handedness, which originates from the excitation of the

A novel compact electromagnetic diode based on Fano resonance is reported, realized by combining a ­defective photonic crystal with a varactor-loaded split ring resonator. One-way response is achieved in a microwave waveguide system, attributed to the sharp asymmetric Fano lineshape, the strong nonlinearity enhancement, and the pronounced nonreciprocal field localization. A low threshold intensity

In this study, we demonstrated an accurate estimation of the refractive index in nanoporous structures using a novel hybrid simulation method that combines electromagnetic field analysis and ray tracing based on wave optics and ray optics. A novel theoretical model for the refractive index in a nanoporous structure was developed using a simulation of the effective medium approximation (EMA) and screening

A Au-Ga alloy layer is synthesized on a Au sheet substrate at low temperature and a new nanoporous Au material is then prepared based on Ga removal from the Au-Ga alloy by a electrochemical method. X-ray diffraction analysis confirms that the grains of the newly formed Au layer are refined and scanning electron microscopy suggests that the newly formed Au layer has a nanoporous structure with a pore

Broadband Mo/Be multilayer structures were designed for maximum uniform normal-incidence reflectivity in a broad range of 111–138 Å, which lies near and beyond the L2,3 absorption edge of Si. A comparison was made of the capabilities of two classes of aperiodic structures and of so-called “stack” structures, which are composed of several periodic structures with different periods stacked one over the

We report new experimental results on the phase-matching properties of AgGa0.86In0.14S2 for second-harmonic generation (SHG) and sum-frequency generation (SFG) of a Nd:YAG laser-pumped KTiOPO4 (KTP), AgGaS2 optical parametric oscillators (OPOs), and a CO2 laser in the 0.615−10.5910 µm spectral range. In addition, we present Sellmeier equations that provide a good reproduction of the present experimental

The metal nanoarray can couple the excitation light energy to the surface, resulting in local electromagnetic field enhancement due to the resonance effect. This is beneficial to the generation of nonlinear optical processes which depend on electromagnetic resonance enhancement, taking advantage of the field enhancement properties of metal nanoarray. Here, silver nanoperiodic arrays are integrated

Terahertz (THz) plays a pivotal part in numerous technology fields in modern times, including the system of the 6th generation wireless communication, imaging and elemental analysis. In addition to light sources and detectors, THz applications require quasi optics as lenses, waveguides, and reflectors for the design of a THz system. Three-dimensional (3D) printing has many advantages. However, 3D printing

Poly (3,4-ethylene dioxythiophene) polystyrene sulfonate (PEDOT:PSS) thin films with tunable optical properties have shown great potential in optoelectronic device applications. Here, we present a new hybrid technology for accurately determining the dielectric properties of PEDOT:PSS films upon bias. Using electrochemical method together with numerical simulation of ellipsometry measurement, significant