Journals
2026 EN
Jia Jiayu · Xiao Yanfang · Yang Lingling
+4 more
Ultrabroadband absorption across the long‐wave and ultralong‐wave infrared (LWIR/ULWIR) spectrum is essential for applications ranging from thermal imaging to spectroscopy, yet remains a persistent challenge. Herein, a refractory metamaterial absorber (MMA) composed of four vertically tapered silicon nitride (Si 3 N 4 ) rods on a tungsten substrate is proposed. Finite element method (FEM) simulations show that the MMA achieves an absorbance of over 90% from 7.15 to 31.62 μm, with a relative bandwidth of 126.23%. Notably, the absorbance peak of the MMA is up to 99.97%, 97.92%, 98.42%, and 99.96% at 7.653, 9.045, 16.762, and 26.731 μm, respectively. An equivalent circuit model corroborates these results and elucidates the underlying impedance matching. The ultra‐broadband performance arises from synergistic coupling of multiple resonant modes, including waveguide resonance (WGR) with higher‐order, Fabry–Pérot (F–P) cavity resonance (FPCR), local surface/propagating plasmon resonance (LSPR/PPR), as well as intrinsic losses of Si 3 N 4 material. The MMA also exhibits wide‐angle stability, maintaining high efficiency for incidence up to 50° under both TE and TM polarizations. It's simple, tunable geometry and fully dielectric composition facilitate fabrication and ensure high‐temperature resilience. This design offers a robust platform for advanced infrared systems, including thermal energy harvesting and spectral imaging.
Journals
2026 EN
Headland Daniel · Kawamoto Yuma · Nedosyko Jordan
+3 more
The advancement of terahertz technology is impeded by a lack of viable options for dynamic reconfigurability in compact systems with fixed low‐loss interconnect. To address this absence, we bring conductive walls into proximity with an unclad microscale silicon waveguide core and thereby supply additional boundary conditions to manipulate guided waves through evanescent interaction. This is analogous to a fiber squeezer, in which a dielectric waveguide's dispersion is manipulated via enclosing walls, but in this case, a crucial distinction is that there is no physical contact whatsoever. Analytical and numerical investigations of this phenomenon show that the presence of the conductive walls increases the cutoff frequency and alters the dispersion profile of the waveguide. We implement proof‐of‐concept demonstrations that exploit this effect to realize mechanically tunable terahertz filters of two types: a high‐pass filter and a resonant notch, operating at ∼300 GHz. This experimental demonstration utilizes a featureless straight dielectric waveguide, and the desired frequency‐selective behavior is implemented contactlessly, and hence reversibly, having made no modification to the waveguide core. The capability for on‐demand dispersion tuning of low‐loss terahertz waveguides holds the potential to realize a broad range of practical reconfigurable systems to support diverse applications of terahertz waves.
Journals
2026 EN
Lozhkina Olga · Muniz Ruth Pinheiro · Singh Shivam
+2 more
The growing demand for advanced data storage and signal processing technologies has intensified the search for novel materials with tunable optical and electronic properties. Chiral 2D perovskites have emerged as promising candidates due to their unique ability to selectively absorb and emit circularly polarized light, as well as to interact with polarizable currents. To exploit these properties in applications, chiral 2D perovskites should be integrated as thin films in various device architectures, yet the means to control their crystallization and film formation processes remain underdeveloped. This study demonstrates that additive engineering can be applied to control the microstructure and strain in chiral 2D perovskite thin films. It is shown that the addition of small amounts of hypophosphorous acid to the precursor solution of (R‐3BrPEA) 2 PbI 4 chiral perovskites results in the dissolution of colloids, leading to a significant increase in the grain size and a release of lattice strain. Consequently, the intensity of their photoluminescence is significantly enhanced, demonstrating that grain boundaries and strain lead to nonradiative recombination losses in chiral 2D perovskites. The findings motivate the exploration of novel additive engineering approaches to improve the optoelectronic quality of chiral 2D perovskite thin films.
Journals
2026 EN
Yoon Jinsu · Kim Jaeyoun · Hong Yongtaek
Quasi‐nondiffracting (QND) optical beams are well known for their long‐range propagation and self‐healing capabilities. Shrinking their beam width down to the mesoscale regime can open up many new applications in microtechnology, but the complexity of the beam‐forming platform remains the major hindrance to its realization. In contrast, the photonic nanojets (PNJs) boast simple platforms for their generation and inherently small beam size, but their utilization has been limited mainly to near‐field applications. This work aims to hybridize the QND and PNJ beam concepts, eventually realizing microscale, self‐healing QND beams using a simple, PNJ‐style platform. To that end, the microscale cuboids made of low‐index dielectric materials are dually utilized, first to generate two self‐decelerating corner‐diffraction beams and then to superpose them into a long‐range (10 λ –100 λ ) microbeam. The QND–PNJ hybridization concept and model will contribute synergistically to the study and application of the microscale optical beams.
Journals
2026 EN
Sweatt Lance · Zhao Xiaolei · LeVaur Taylor
+7 more
Passively phased coherent laser systems have been extensively studied for their potential to reduce design complexity in applications requiring high radiance. In this letter, the experimental demonstration of a five‐element angled laser diode array coupled to a slab waveguide cavity integrated onto a single chip in a monolithic FIRE configuration is presented. Using this configuration, the common FIRE cavity performs coherent combination of the individual lasers in the array, providing high inter‐element coupling and reduced edge losses to allow single supermode operation. Quasi‐continuous‐wave operation and high‐visibility fringes in the far field (V = 98%) that demonstrate excellent coherence of the laser array are experimentally demonstrated.
Journals
2026 EN
Li Zeting · Xu KaiDa · Wen Pin
In this article, a waveform‐selective antenna that integrates the functions of waveform selectivity, electromagnetic (EM) shielding, and EM wave radiation has been proposed. By integrating different nonlinear circuits and selecting appropriate component values, the antenna can achieve high reflection of either a pulse wave (PW) or a continuous wave (CW) at the same frequency, while allowing the other waveform to transmit with minimal interference. When exposed to pulse waves (PWs) of varying pulse widths, the antenna can adaptively process them by adjusting the values of its capacitive or inductive components. The proposed design introduces an additional degree of freedom for manipulating EM waves in the terahertz (THz) band, that is, the ability to select the time‐domain waveform. Combining functional integration with a compact size, the waveform‐selective antenna holds significant potential for a range of applications, including detection, EM shielding, and THz communications.
Journals
2026 EN
Kokars Valdis · Paulsone Patricija · Laipniece Lauma
+3 more
A series of glassy 5‐substituted 8‐hydroxyquinolinato aluminum complexes with good film‐forming ability via wet‐casting methods were successfully synthesized in sufficient purity by using aluminum nitrate and investigated for applications in tris(8‐hydroxyquinolinato)aluminum (Alq 3 ): 4‐(dicyanomethylene)‐2‐methyl‐6‐(4‐dimethylaminostyryl)‐4 H ‐pyran (DCM)‐type organic solid‐state lasers systems. Synthesized glassy Alq 3 complexes form neat films from solutions and show glass transition temperatures up to 108°C with thermal stability above 156°C. The incorporation of bulky triphenyl and Boc groups through methoxy and methylpiperazine linkers in 5‐position of the 8‐hydroxyquinolinato ligands only slightly influenced absorption and emission characteristics of synthesized Alq 3 complexes in comparison to the unsubstituted Alq 3 . A twofold increase in photoluminescence quantum yield of synthesized complexes in the solid state (up to 18.8%) relative to solution (up to 9.3%) is observed. This behavior is attributed to aggregation‐induced emission arising from restricted intramolecular motions in the amorphous films, despite the presence of concentration‐dependent aggregation‐caused quenching at intermediate aggregation levels. A successful demonstration of Förster resonance energy transfer (FRET) from a bulky 2‐(4‐methylpiperazin‐1‐yl)ethyl‐3,3,3‐triphenylpropanoate‐substituted aluminum complex to a solution‐processable DCM derivative confirms the feasibility of fully solution‐processed Alq 3 :DCM‐type light‐emitting gain media, enabling wet‐casting deposition strategies for the design, investigation, and fabrication of organic solid‐state lasers.
Journals
2026 EN
Nguyen Van Minh · Kanamori Yoshiaki
Micro‐electro‐mechanical system (MEMS) actuator arrays integrated into the gap of split‐ring resonators (SRRs) that are capacitively coupled to a spoof‐surface‐plasmon‐polariton (SSPP) waveguide are numerically designed and experimentally fabricated. Owing to its compact size and lightweight structure, the microbridge exhibits high‐speed operation with a mechanical resonant frequency of 1.505 MHz in air. The microbridges are capacitively actuated by embedded lead electrodes and grounded microbridge arrays. When an alternating current (ac) voltage V ac of 30 V is applied, a maximum phase shift of 2.55° is achieved at 6.65 GHz, whereas a direct current (dc) voltage V dc of 140 V results in a maximum phase shift of 2.96° at 7.95 GHz. Theoretical analysis and numerical simulations reveal that the voltage‐induced deformation of the microbridge alters the dispersion properties of the SSPP waveguide and perturbs the local electric field beneath the bridge, thereby enabling phase modulation of the guided microwave signal. These findings demonstrate the capability of the device to function as an active phase modulator for integrated microwave circuits, with potential applications in 5 G/6 G communication systems and time‐varying metamaterials.
Journals
2026 EN
Cojocari Maria · Ibrahim Eman · Basharin Alexey
We report on the design, fabrication, and experimental characterization of a free‐standing terahertz metasurface supporting quasi‐bound states in the continuum (quasi‐BICs). The metasurface, realized by laser cutting double‐slot apertures in a thin brass foil, exhibits a tunable transition from symmetry‐protected BICs to sharp Fano‐type resonances when structural asymmetry is introduced. Terahertz time‐domain spectroscopy measurements confirm high‐Q resonances in good agreement with simulations. Multipole decomposition reveals that the trapped mode response is dominated by the in‐plane electric quadrupole component, which governs the confinement and radiation properties of the quasi‐BIC. The free‐standing design eliminates substrate‐induced losses and opens a robust route toward versatile, high‐performance terahertz devices. These findings demonstrate the potential of quasi‐BIC metasurfaces as compact, tunable high‐Q resonators for applications in sensing, filtering, and terahertz photonics.
Journals
2026 EN
Kuo ChengTing · Chen TingYu · Huang PoRei
+3 more
GeSn has emerged as a promising alternative in Si photonics due to its narrow and tunable bandgap. In this study, GeSn waveguide photodetectors (WGPDs) based on a lateral p–i–n homojunction architecture are demonstrated. Incorporating 10.82% Sn effectively reduces the bandgap, extending the photodetection range to 2745 nm and covering the entire short‐wave infrared (SWIR) region. A lateral p–i–n homojunction diode with good optical confinement and long photon‐absorbing length is developed to significantly enhance the optical responsivity. The close proximity of the direct (Γ c ) and indirect ( L c ) conduction bands allows excitation of electrons from Γ c to L c , increasing electron lifetime. As a result, the carrier collection efficiency improves with higher bias. This momentum‐space separation mechanism enables device operation at a low electric field of ≈2.5 kV cm −1 . These findings suggest that the fabricated GeSn WGPDs are strong candidates for full‐range SWIR detection applications.