Self-balanced and self-phase-corrected electro-optic sampling in a birefringent crystal.

Mid-to-far-infrared (IR) spectral content is recorded using the novel self-balanced and self-phase-corrected electro-optical (EO) sampling arrangement. Self-balancing guarantees that the electric field emerging from the EO crystal yields a signal of zero via a Wollaston prism and balanced photodetector (i.e.

Enhanced terahertz radiation directivity via a conical horn antenna from on-chip spintronic emitters.

A circular waveguide-fed conical horn antenna is fabricated using two-photon lithography (TPL) and integrated with a spintronic terahertz radiation emitter source to provide enhanced radiation directivity. In comparison to the bare terahertz radiation source, incorporating the antenna permits a spectral density gain up to 20.5 dB.

Electro- and Photo- Dual Responsive Chromatic Devices for High-Contrast Dimmers.

Electrochromism stands out as a highly promising technology for applications including variable optical attenuators, optical switches, transparent displays, and dynamic windows. The pursuit of high-contrast tunability in electrochromic devices remains a challenging goal. Here, the first photochromic hydrogel electrolyte is reported for electro- and photo-dual responsive chromatic devices that yield a high transmittance contrast at 633 nm (ΔT = 83.

Enhanced Green Light Emission from a Silicon-Based Metal-Encapsulated Nanoplasmonic Waveguide.

Integrated silicon plasmonic circuitry is becoming integral for communications and data processing. One key challenge in implementing such optical networks is the realization of optical sources on silicon platforms, due to silicon's indirect bandgap. Here, we present a silicon-based metal-encapsulated nanoplasmonic waveguide geometry that can mitigate this issue and efficiently generate light via third-harmonic generation (THG).

Fast and Stable Zinc Anode-Based Electrochromic Displays Enabled by Bimetallically Doped Vanadate and Aqueous Zn/Na Hybrid Electrolytes.

Vanadates are a class of the most promising electrochromic materials for displays as their multicolor characteristics. However, the slow switching times and vanadate dissolution issues of recently reported vanadates significantly hinder their diverse practical applications. Herein, novel strategies are developed to design electrochemically stable vanadates having rapid switching times.

Methodology for computing Fourier-transform infrared spectroscopy interferograms.

With the utilization of Fourier-transform infrared (FTIR) spectroscopy for a multitude of commercial applications, a robust methodology for designing, implementing, and servicing these systems in commercial settings is becoming increasingly paramount. Here we present a method allowing for the numerical evaluation of the interferogram signal in a FTIR spectroscopy system, in which the incident electric field can exhibit any arbitrary spectral content. The developed model assesses multiple internal reflections occurring within a beam splitter (BS) and compensating plate (CP), allows for the presence or absence of the CP, and obtains the interferogram in absolute units.

Intra-pulse difference frequency generation in ZnGeP for high-frequency terahertz radiation generation.

The highly-nonlinear chalcopyrite crystal family has experienced remarkable success as source crystals in the mid-infrared spectral range, such that these crystals are primary candidates for producing high terahertz frequency (i.e., [Formula: see text] 10 THz) electric fields.

Generation of 17-32 THz radiation from a CdSiP crystal.

A phase-resolved electric field pulse is produced through the second-order nonlinear process of intra-pulse difference frequency generation (DFG) in a (110) CdSiP chalcopyrite crystal. The generated electric field pulse exhibits a duration of several picoseconds and contains frequency components within the high-frequency terahertz regime of ∼17-32 THz. The intra-pulse DFG signal is shown to be influenced by single-phonon and two-phonon absorption, the nonlinear phase-matching criterion, and temporal spreading of the excitation electric field pulse.

Advances in electrochromic device technology through the exploitation of nanophotonic and nanoplasmonic effects.

Research regarding electrochromic (EC) materials, such materials that change their color upon application of an electrochemical stimulus, has been conducted for centuries. However, most recently, increasing efforts have been put into developing novel solutions to utilize these on-off switching materials in advanced nanoplasmonic and nanophotonic devices. Due to the significant change in dielectric properties of oxides such as WO, NiO, MnO and conducting polymers like PEDOT:PSS and PANI, EC materials have transcended beyond simple smart window applications and are now found in plasmonic devices for full-color displays and enhanced modulation transmission and photonic devices with ultra-high on-off ratios and sensing abilities.

Emission and sensing of high-frequency terahertz electric fields using a GaSe crystal.

A GaSe crystal cut along the (001) crystallographic plane is investigated for the emission and detection of high-frequency (i.e. up to ∼20 THz) electric fields.

On-chip high ion sensitivity electrochromic nanophotonic light modulator.

Since the discovery of electrochromism, the prospect of employing various electrochromic materials for smart window glass, variable reflectivity mirrors, and large-area displays has been the main drive for such an intriguing phenomenon. However, with advances in nanofabrication and the emergence of improved electrochromic materials offering reversible large changes in dielectric properties upon electrically induced redox reactions, the application strategies are starting to encompass the field of nanophotonics and nanoplasmonics. Herein, a novel strategy is proposed and demonstrated for offering both ultrahigh light modulation depth and high sensitivity ion detection in a single nanophotonic waveguiding platform.

Nanoscale All-Solid-State Plasmochromic Waveguide Nonresonant Modulator.

Plasmochromics, the interaction of plasmons with an electrochromic material, have spawned a new class of active plasmonic devices. By introducing electrochromic materials into the plasmon's dielectric environment, plasmons can be actively manipulated. We introduce inorganic WO and ion conducting LiNbO layers as the core materials in a solid-state plasmochromic waveguide (PCWG) to demonstrate light modulation in a nanoplasmonic waveguide.

Transparent Zinc-Mesh Electrodes for Solar-Charging Electrochromic Windows.

Newly born zinc-anode-based electrochromic devices (ZECDs), incorporating electrochromic and energy storage functions in a single transparent platform, represent the most promising technology for next-generation transparent electronics. As the existing ZECDs are limited by opaque zinc anodes, the key focus should be on the development of transparent zinc anodes. Here, the first demonstration of a flexible transparent zinc-mesh electrode is reported for a ZECD window that yields a remarkable electrochromic performance in an 80 cm device, including rapid switching times (3.

Generation of narrowband terahertz radiation via phonon mode enhanced nonlinearities in a BaGaSe crystal.

We report on narrowband terahertz (THz) radiation generation via optical rectification from a crystal. The dense phonon mode distribution of the crystal causes narrow transmission bands in the THz frequency range with enhanced nonlinear susceptibility magnitudes, thus permitting strong narrowband THz radiation generation at the frequencies of 1.97 and 2.

Transparent inorganic multicolour displays enabled by zinc-based electrochromic devices.

Electrochromic displays have been the subject of extensive research as a promising colour display technology. The current state-of-the-art inorganic multicolour electrochromic displays utilize nanocavity structures that sacrifice transparency and thus limit their diverse applications. Herein, we demonstrate a transparent inorganic multicolour display platform based on Zn-based electrochromic devices.

Backward terahertz difference frequency generation via modal phase-matching in a planar LiNbO waveguide.

The backward difference frequency generation process is used to produce narrowband terahertz radiation via modal phase-matching in a --air planar waveguide. The pump mode, signal mode, and or idler modes are selected to satisfy the backward difference frequency generation phase-matching condition, thus allowing narrowband (i.e.

Dependence on excitation polarization and crystal orientation for terahertz radiation generation in a BaGaSe crystal.

Optical rectification is experimentally investigated in a biaxial BaGaSe crystal by considering various combinations of near-infrared excitation polarizations and crystal orientations. The highest terahertz radiation is produced along the Z crystallo-physical direction of the BaGaSe crystal. Despite the optical complexity of the BaGaSe crystal in the terahertz spectral regime, this systematic experimental investigation determines the optimal excitation polarization and crystal orientation for the optical rectification process.

Simultaneously enabling dynamic transparency control and electrical energy storage via electrochromism.

Transparency-switchable electrochromic devices (ECDs) offer promising applications, including variable optical attenuators, optical shutters, optical filters, and smart windows for energy-efficient buildings. However, the operation of conventional ECDs requires external voltages to trigger coloration/de-coloration processes, which makes them far from being an optimal energy-efficient technology. Electrochromic batteries that incorporate electro-optical modulation and electrical energy storage functionalities in a single platform, are highly-promising in the realization of energy-efficient ECDs.

Theoretical formalism for off-normal angular coupling into selective and parity-dependent modes in a planar waveguide.

A theoretical formalism is presented to describe coupling of an electromagnetic field into the modes of a planar waveguide, where the electromagnetic field has a non-uniform transverse profile and is incident at an arbitrary angle. The theoretical approach is used to investigate coupling of a Gaussian electromagnetic field into a ${{\rm LiNbO}_3}$LiNbO planar waveguide, where the calculations are shown to be in excellent agreement with finite-different time-domain simulations. This formalism is essential to phase-matched frequency-conversion waveguides based on nonlinear optical phenomena, which can rely on coupling the excitation field into selective higher-order waveguide modes of either even or odd parity.

Plasmochromic Nanocavity Dynamic Light Color Switching.

Static plasmonic metal-insulator-nanohole (MIN) cavities have been shown to create high chromaticity spectral colors for display applications. While on-off switching of said devices has been demonstrated, introducing active control over the spectral color of a single cavity is an ongoing challenge. Electrochromic oxides such as tungsten oxide (WO) offer the possibility to tune their refractive index (2.

Electrochemical Stability Enhancement of Electrochromic Tungsten Oxide by Self-Assembly of a Phosphonate Protection Layer.

The presented work demonstrates an innovative method to overcome electrolyte restrictions for electrodeposited tungsten oxide (WO) electrochromic electrodes. By self-assembly of a phosphonic acid protection layer on top of the WO electrode, the cycle life of a WO electrode in aqueous electrolytes of potassium (KCl) and lithium chloride (LiCl) is dramatically enhanced. Based on the hydrophobic nature of the self-assembled monolayer (SAM), the modification allows for ion intercalation while it prevents etching of the electrode.

Correction: Rechargeable Zn/Al dual-ion electrochromic device with long life time utilizing dimethyl sulfoxide (DMSO)-nanocluster modified hydrogel electrolytes.

[This corrects the article DOI: 10.1039/C9RA06785J.].

Femtosecond Laser Pulse Ablation of Sub-Cellular Drusen-Like Deposits.

Age-related macular degeneration (AMD) is a condition affecting the retina and is the leading cause of vision loss. Dry AMD is caused by the accumulation of lipid deposits called drusen, which form under the retina. This work demonstrates, for the first time, the removal of drusen-like deposits underneath ARPE-19 cell layers using femtosecond laser pulses.

A modeling of dispersive tensorial second-order nonlinear effects for the finite-difference time-domain method.

A generalized formalism is developed to model second-order nonlinear processes in finite-difference time-domain (FDTD) simulations. The method is capable of modeling frequency-conversion from all 18 elements of the second-order nonlinear tensor, where dispersion of the tensor elements is included at both the pump and generated frequencies. The model is validated by considering frequency-conversion in a LiNbO crystal, which has highly dispersive second-order nonlinear susceptibilities near the phonon resonances.

Oxygen-Vacancy-Tunable Electrochemical Properties of Electrodeposited Molybdenum Oxide Films.

Molybdenum oxides have been widely studied in recent years, owing to their electrochromic properties, electrocatalytic activities for hydrogen evolution reactions (HERs) and excellent energy storage performance. These characteristics strongly depend on the valence states of Mo in the oxides such as IV, V, and VI, which can be efficiently altered through oxygen deficiencies within the oxides. Here, we present a colloidal electrodeposition method to introduce oxygen vacancies in such Mo oxide films.