Titanium nitride (TiN) is a promising plasmonic material with hard and abrasion-resistant specialities. In this study, a gain regime, namely, plasmon-enhanced random laser emission, is demonstrated in the Pyrromethene-597 (PM597) assisted by titanium nitride (TiN) film. For this, photoluminescence and random lasing are measured at different pumping energies from PM597/Silicon and PM597/TiN/Silicon

Investigating new materials plays a very important role for advancing the field of nanofabrication and nanoplasmonics. Even though niobium nitride (NbN) is mainly known for its superconducting properties when fabricating superconducting nanowire single-photon detectors, we demonstrate that it is also a material for plasmonic nanoantenna applications. In this work we measure physical properties of thin

A multi-material microstereolithography system in which multiple photocurable resins are stored on a single glass palette was developed to produce multicolor three-dimensional (3D) models. Multiple photocurable resins with different colors are replaced by moving a linear translational X-stage that supports the glass palette. A Z-stage moves radially to remove the air bubbles that adhere around the

Cu-based micropatterns were fabricated using reductive sintering inside Cu2O nanosphere films induced by green femtosecond laser pulses. The linear and nonlinear absorption coefficients of Cu2O nanosphere films composed of Cu2O nanospheres, polyvinylpyrrolidone, and 2-propanol were 0.062 × 104 /cm and 10−50 cm/GW, respectively. The minimum line width was the same as the laser spot diameter (∼0.7 µm)

Semiconductor nanowires have attracted much attention for photonic applications, especially for lasers, because of their availability in a wide variety of materials and compositions, exceptionally small size, and rich functionality. So far, most nanowire laser studies have been done in rather short wavelength (λ) ranges of less than 1 µm. In addition, the diameter (d) of most nanowire lasers has been

Chalcogenide-oxide Bragg reflectors and a 1-D vertical cavity for operation at 1.55 µm were designed and fabricated via radio-frequency sputtering. The Bragg reflectors were made out of repeating layers of Al2O3 and As2Se3, and the cavity was obtained via a Ga5Ge20Sb10S65:Er3+ defect layer. The layers’ properties were assessed via ellipsometry and SEM imaging. Transmission spectroscopy verifies the

Chirped and apodized grating couplers were designed, fabricated and characterized in lithium niobate thin film for fiber-to-chip coupling. The maximum coupling efficiency of -1.8 dB and -6.9 dB for TE mode at a wavelength of 1550 nm was simulated and measured, respectively. The discrepancies were mainly attributed to the different fabrication errors of local periods and groove widths, which hampered

Planar photonics technology is expected to facilitate new physics and enhanced functionality for a new generation of disruptive optical devices. To analyze such planar optical metasurfaces efficiently, we propose a prismatic discontinuous Galerkin time domain (DGTD) method with a generalized dispersive material (GDM) model to conduct the full-wave electromagnetic simulation of planar photonic nanostructures

Silicon waveguide structures are a viable alternative for the transmission of signals over a wide range of frequencies, and new fabrication methods are key to increased applications. In this work, THz transparency of silicon-core, silica clad fibers, refined using a traveling solvent method, is demonstrated. The ≈ 200 µm core of these fibers is shown to have good transmission from 4.8–9 µm and 1–7

Catalyst-free, position-controlled indium arsenide (InAs) nanowires (NWs) of variable diameters were grown on Si (111) by selective-area epitaxy (SAE). Ultrafast pump-probe spectroscopy was conducted, from which carrier recombination mechanisms on the NW surface and interior were resolved and characterized. NWs grown using SAE demonstrated high optical quality, showing minority carrier lifetimes more

Wideband optical saturable absorbers (SA) are an ideal laser component for pulse laser generation in different wavelengths, which has attracted tremendous attention in recent years. Herein, a MoO3-x-based novel wideband optical SA has been demonstrated by utilizing it for ∼1/1.5/2 μm Q-switched pulses generation. After separately integrating the MoO3-x-SA into Yb-, Er- and Tm-doped fiber lasers, passively

The optical properties of the polymer composites consisting of polyvinyl chloride nanofibers and polypropylene films in the frequency range of 0.2–1.0 THz were studied, and the mechanical properties of polyvinyl chloride nanofibers and the structure porosity were investigated. An iterative mathematical model based on effective medium theory was used to describe the effective refractive index and absorption

Gallium nitride (GaN) films on high-thermal-conductivity substrates have attracted considerable attention for their applications in high-power light-emitting diodes and electronic devices. Herein, a 2-inch 8-µm-thick thermostable GaN/Mo template with Ga-face was fabricated via two consecutive layer transfer technique. The full-widths at half-maximum for the x-ray rocking curves of GaN (002) and (102)

We present a study on temperature dependent spectroscopic data for Yb:KGW, Yb:KYW and Yb:YLF between 80 K and 280 K and Yb:YAP between 100 K and 300 K. Absorption and emission cross sections are determined. The latter ones are obtained by using a combination of the McCumber relation and the Füchtbauer-Ladenburg equation. Fluorescence lifetimes are measured within a setup optimized for the suppression

Absorptive metamaterials made of epsilon-near-zero indium tin oxide and silicon dioxide films are designed and fabricated for wideband perfect light absorption near the epsilon-near-zero wavelength. By increasing the number of bilayers, we achieve over 90% absorption in a spectral bandwidth of 0.95 microns.

Cholesteric liquid crystals form a right-angle helicoidal structure with the pitch in the submicrometer and micrometer range. Because of the periodic modulation of the refractive index, the structure is capable of Bragg and Raman-Nath diffraction and mirrorless lasing. An attractive feature of cholesterics for optical applications is that the pitch and thus the wavelength of diffraction respond to

Optical polymers cover only a rather narrow range of optical properties. This is a limiting factor for the design of polymer-based optical systems such as smartphone cameras. Moreover, it also poses a problem for femtosecond two-photon lithography, which is a state-of-the-art technology to 3D print high-quality optics from photopolymers. To overcome the limitations of conventional polymers, we introduce

We demonstrate the fabrication of optical elements on the millimeter scale by stitching-free 3D printing via two-photon polymerization, using a commercial microfabrication system (Nanoscribe GmbH). Previous limitations are overcome by the use of a large writing field objective as well as a novel high transparency resist. The printed optical components are free of stitching defects due to a single step

We report on the first laser operation of ytterbium-doped potassium yttrium double molybdate crystal (Yb:KY(MoO4)2). Single-crystals containing 3 at.% Yb3+-ions were grown by the low temperature gradient Czochralski method. The crystal structure (orthorhombic, sp. gr. D142h – Pbna) was refined with the Rietveld method. Yb:KY(MoO4)2 exhibits a layered structure leading to a strong optical anisotropy

In this study, we investigated the temperature dependence of the initial deformation and cracks of indium tin oxide (ITO) thin films deposited on a fused silica substrate using a 1064-nm quasi-continuous-wave laser. We observed that the laser-induced morphology threshold of the film shows a dramatic thickness effect. The laser-induced morphology threshold of a 100-nm ITO film is four times that of

Auger electron spectroscopy (AES) as a method to characterize the ferroelectric polarization domains in magnesium-doped lithium niobate crystals is demonstrated. Preliminary measurements on a test sample show a clearly identifiable relative shift in the energy of the Auger oxygen KLL transition peak between poled (inverted) and un-poled domains. Auger electrons detected from the negative polarization

High-birefringence waveguide Bragg gratings for the C-band are fabricated in the Silica-on-Silicon platform with Displacement Talbot Lithography (DTL). Transmission and reflection spectrums of the Bragg wavelength splitting were measured and calculated. The birefringence here is up to 7.919×10−4 to 1.670×10−3, much higher than existing devices via other platforms. We illustrate the principle and advantage

Photodetectors are key optoelectronic building blocks performing the essential optical-to-electrical signal conversion, and unlike solar cells, operate at a specific wavelength and at high signal or sensory speeds. Towards achieving high detector performance, device physics, however, places a fundamental limit of the achievable detector sensitivity, such as responsivity and gain, when simultaneously

In this paper, artificial opals, made of 300-nm-diameter nanoporous SiO2 globules by sedimentation of a colloidal suspension and annealing at different temperatures in the range of 200–1500 °C, are studied as a promising material platform for terahertz (THz) optics. Our findings reveal that THz optical properties of such materials can be predictably varied in a wide range by annealing, while being

The manufacturing of low loss chalcogenide glasses (ChGs) for optoelectronic applications is ultimately defined by the concentration of impurities present in starting materials or imparted via processing. We describe a rapid method for purifying metallic starting materials in As2Se3 glass where oxide reduction is correlated to optical and physical properties. Specifically, As-O reduction enhances the

The precise characterisation of the ground state absorption cross section around 800 nm for Nd:YAG from room temperature to liquid nitrogen temperature is presented. These results enabled the measurement of the energy transfer upconversion macroparameter over the same temperature range for 0.3at.%- and 0.6at.%-doped samples via a simple automated z-scan technique. The main absorption cross section

Special nonuniform doping profiles are proposed for Fe2+:ZnSe crystals, which can increase the output energy of Fe2+:ZnSe lasers in comparison with those based on active elements with a uniform distribution of the doping agent. We present the simulation results for thermoelastic stresses and distortions of the optical density that arise in a Fe2+:ZnSe crystal during pulsed pumping, with the Fe distribution

Middle-infrared luminescence of bulk Al:Cr:ZnSe crystal under direct electrical excitation of Cr2+,5E− 5T2 transition, is reported. Effective cross-section of electrical excitation was estimated based on comparative luminescence measurements under electrical and optical (1560 nm) excitations. Calculation of the threshold current density for lasing under electrical excitation of this material was also

We present Emission and absorption cross sections of thulium doped calcium fluoride (Tm:CaF2) in the visible to short wave infrared (SWIR) wavelength range for temperatures between 80 K and 300 K. For spectral regions of high and low absorption the McCumber relation and the Fuchtbauer–Ladenburg equation have been used to give reliable results. Furthermore, an estimation for the cross relaxation efficiency

The spectroscopic properties and laser operation of thulium-doped tantalum pentoxide (Tm:Ta2O5) waveguides are reported in this paper. Fluorescence ranging from 1600 nm to 2200 nm, corresponding to the 3F4 → 3H6 transition was observed from 3 wt% Tm:Ta2O5 waveguides pumped at a wavelength of 795 nm. Measurements of excited-state lifetime, the emission and absorption spectra, with subsequent calculation

Direct laser writing of luminescent patterns within the material consisting of the polymer (PMMA) matrix with dissolved precursor (TEDBCd) molecules is demonstrated. The luminescence here is related to the UV induced growth of CdS nanoparticles. The irradiation was performed by the third harmonic of a Nd:YAG laser with a pulse duration of 15 ns. The irradiated polymer films were kept at ambient temperatures

Chalcogenide based micro-devices, including integrated photonic waveguides and metasurfaces, have broad applications from mid-infrared nonlinear optical signal processing to reconfigurable photonic metasurfaces. Laser machining is a flexible and cost-effective method for lithography-free patterning and postprocessing of large scale microphotonics. In the past, patterning of chalcogenide thin film materials

Controlling light flow in the directed-assembly of blue-phase liquid crystal (BPLC) microspheres with curvature boundaries and random domain of cubic lattices is a highly interesting photonic phenomenon. A strategy of efficient random lasing with resonant feedback based on a microemulsion comprising of BPLC, laser dye and block copolymer is presented here. BPLCs are produced with a microfluidic apparatus

Achieving switchable and diversified functionalities in a single metasurface has garnered great research interest for potential terahertz applications. Here, we propose and demonstrate a phase-change metasurface that simultaneously supports broadband electromagnetically induced transparency (EIT) and broadband nearly perfect absorption, depending on the phase state of a phase change material-vanadium

The effectiveness of a highly sensitive sodium dodecyl benzenesulfonate (SDBS)–TiO2 thin film optical waveguide gas sensor assessed in detecting various organic gases. Gas sensing measurements indicated that the sensing element has good selectivity, high sensitivity, and a low detection limit of 1 ppb to xylene gas with fast response and short recovery times. Interference gas test results showed that

In this paper, a metamaterial absorber that achieved absorption tuning by electricity and light control has been proposed in the terahertz (THz) regime. The THz absorber exhibits an absorbance of 97.5% at a resonant frequency of 0.245 THz. First, we simulated the absorption spectra under different structural parameters. Then the absorption characteristics are analyzed under different Fermi energies

We present a bifunctional polarization converter based on Dirac semimetals (DSMs) and vanadium dioxide (VO2), which consists of two layers of DSMs on both sides, a metal grating and a VO2 board. The polarization converter frequency is dynamically tuned by changing the Fermi energy level of the DSMs. The result suggests that when VO2 is in an insulated state, the device behaves as a transmissive polarization

Gold nanoparticles were prepared in a carbon quantum dots solution using the laser ablation technique to enhance the photoluminescence property of a carbon quantum dots solution. The gold plate was ablated using a Q-Switched Nd:YAG laser at 4, 8, 12, and 16 minutes with a stable laser energy. The optical properties, functional groups, and the morphology of the prepared samples were examined using UV-visible

Hematite (α-Fe2O3), as one of the most prevalent transition metal oxides (TMOs) on the Earth, has been the hot spot of intense research for recent decades. Understanding the optical signatures in hematite is essential for the design of α-Fe2O3-based devices in the photoelectrochemical and photonic fields. In the present work, we successfully synthesized hematite nanoflakes by the facile oil bath method

We measure the birefringence of the nonlinear optical (NLO) properties of cadmium silicon phosphide via the Z-scan technique at near and mid-infrared wavelengths. We discuss the implications of the NLO properties on optical parametric amplifier performance. We find that the nonlinear absorption does reduce the conversion efficiency, while the nonlinear refraction has a negligible effect.

We developed a novel technique to evaluate the elasto-optic coefficients of electrooptic (EO) single crystals. Notably, this method uses the deformation of the crystal generated by the space charge formed by the electrons injected into the crystal. For the first time, to our knowledge, the coefficient p12 was quantified separately from p11 for KTa1-xNbxO3(KTN) with this method. Both the coefficients

In this work we present a novel optical polymer system based on polyurethane elastomer components, which combines excellent UV transparency with high thermal stability, good hardness, high surface tension and long pot life. The material looks very promising for encapsulation and microlensing applications for chip-on-board (CoB) light-emitting diodes (LED). The extinction coefficient k, refractive index

Hybrid exciton states can be formed under the strong coupling of plasmons excited by metal nanostructures and excitons. Because of the large exciton binding energy, black phosphorus (BP) is an ideal platform to investigate the strong coupling. In this paper, we first demonstrate the strong coupling between local surface plasmon modes of different metal nanostructures and excitons in monolayer BP by

InGaN/GaN multiple quantum wells (MQWs) were fabricated under the same growth conditions on the planar and patterned sapphire substrates (PSS) with 10 nm and 20 nm sputtering AlN layers, respectively. Photoluminescence and electroluminescence results both showed that MQWs samples have significant differences in emission wavelengths. The wavelength of the samples on planar substrate is about 20 nm longer

AlGaN-based germicidal UV LEDs show promise in fighting the COVID-19 pandemic through disinfection of air, water, and surfaces. We report UV LEDs grown by MOCVD on SiC substrates, fabricated into thin-film flip chip devices. Replacing the uniform p-AlxGa1-xN layer (x = 0.2) with a short-period-superlattice of alternating (x = 0.1 and 0.8) Al-composition improved EQE from 1.3% to 2.7% (3.2% with encapsulation)

Silicon-tin (Si1-xSnx) films have been grown using plasma-enhanced chemical vapor deposition on Si (001) substrate. X-ray photoelectron spectroscopy characterization of the thin films show successful substitutional incorporation of Sn in Si lattice up to 3.2%. The X-ray diffraction characterizations show epitaxial growth of Si1-xSnx films (001) direction. The Sn incorporation has been measured using

The chalcogenide semiconductor antimony telluride exhibits a sub-unitary refractive index as low as 0.7 at mid- to near-UV wavelengths between 220 and 400 nm, with the spectral width of the sub-unitary band, minimum index and associated extinction coefficient being controllable functions of alloy composition. As such it can enable step-index hollow-core optical waveguiding at ultraviolet wavelengths

Designing an efficient emitter design is an important step for achieving a highly efficient TPV conversion process. Wavelength-selective emissivity, spectra match between the emitter and TPV cells, and high thermal stability are three main characteristics that must be considered before implementing the emitter. In this work, an indium tin oxide (ITO)/sapphire emitter structure is investigated for TPV

Control of lasing properties through tailorable and dynamically tunable materials and reconfigurable compositions can augment the performance of random lasers for a wide range of applications. Here, a colloid of randomly dispersed weakly scattering single-layer titanium carbide (Ti3C2Tx) MXene flakes embedded within rhodamine 101 gain medium is experimentally shown to provide feedback for random lasing

We demonstrate a monolayer MoS2-based saturable absorber (SA) synthesized by chemical vapor deposition (CVD). The as-grown SA has high spatial homogeneity and shows excellent saturable absorption properties in the 2 µm wavelength region. A higher modulation depth of 21.3% and lower saturation intensity of 0.47 MW/cm2 are achieved compared with those of other documented MoS2 SAs to date. When applying

We demonstrate a monolayer MoS2-based saturable absorber (SA) synthesized by chemical vapor deposition (CVD). The as-grown SA has high spatial homogeneity and shows excellent saturable absorption properties in the 2 µm wavelength region. A higher modulation depth of 21.3% and lower saturation intensity of 0.47 MW/cm2 are achieved compared with those of other documented MoS2 SAs to date. When applying

Hematite (α-Fe2O3), as one of the most prevalent transition metal oxides (TMOs) on the Earth, has been the hot spot of intense research for recent decades. Understanding the optical signatures in hematite is essential for the design of α-Fe2O3-based devices in the photoelectrochemical and photonic fields. In the present work, we successfully synthesized hematite nanoflakes by the facile oil bath method

Control of lasing properties through tailorable and dynamically tunable materials and reconfigurable compositions can augment the performance of random lasers for a wide range of applications. Here, a colloid of randomly dispersed weakly scattering single-layer titanium carbide (Ti3C2Tx) MXene flakes embedded within rhodamine 101 gain medium is experimentally shown to provide feedback for random lasing

Editor-in-Chief Alexandra Boltasseva introduces new Optical Materials Express Associate Editors Shekhar Guha and Germano Montemezzani.

The dual-wavelength-driven shrinkage of metal microstructures and hydrogel actuation are demonstrated by the fabrication of multi-metal microstructures in hydrogels by multiphoton photoreduction. Silver and gold microstructures were fabricated in a poly-N-isopropylacrylamide (PNIPAm) hydrogel. Because of the different optical resonances of the metals, wavelength-dependent shrinkage of metal microstructures

Metamaterials and plasmonics potentially offer an ultimate control of light to enable a rich number of non-conventional devices and a testbed for many novel physical phenomena. However, optical loss in metamaterials and plasmonics is a fundamental challenge rendering many conceived applications not viable in practical settings. Many approaches have been proposed so far to mitigate losses, including

The optical fiber geometry is known for rugged, high power laser sources that are preferred for many applications, but is typically limited to the visible and near-infrared regions of the electromagnetic spectrum due to the transmission limits of silica (< 2 µm). This wavelength range could be extended into the mid-infrared using transition metal doped, crystalline II-VI optical gain media, but these

Development of high numerical aperture fiber bundles (FBs) requires use of thermally matched pair of glasses with a high difference of refractive indices. We have developed a pair of glasses with high refractive index contrast ΔnD>0.2, suitable for fabrication of optical fiber bundles with numerical aperture NA > 0.85. Core glass was synthetized in the lanthanum oxide system Nb2O5-Ta2O5-SiO2-ZrO2-

Herein we describe the synthesis, crystal structures, photoluminescence (PL) and cathodoluminescence (CL) spectra of phosphors in the Sr0.97-xBaxEu0.03Al2O4 system between x = 0 and x = 0.97. The syntheses of these phosphors were carried out by solid state reactions at 1350°C in mixed gas (H2/N2). The molar fractions of the alkaline earth elements were varied in steps of 0.1. The Sr1-xBaxAl2O4 series

In this article the photoluminescence (PL) and cathodoluminescence (CL) of undoped BaAl2O4 and BaAl2O4 doped with 500 ppm and 3 mol% Eu2+ is described. The most important results from the CL measurements are: (1) Undoped BaAl2O4 manifested intrinsic CL at 460 nm, which increased at low temperature and did not change significantly upon exposure to the e-beam; (2) Doping BaAl2O4 with Eu2+ changed the