An all-dielectric Fano resonance sensor is proposed, and its sensing characteristics are numerically investigated in the near-infrared region. The proposed device comprises two planar waveguides and a grating. The cou...
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An all-dielectric Fano resonance sensor is proposed, and its sensing characteristics are numerically investigated in the near-infrared region. The proposed device comprises two planar waveguides and a grating. The coupling between high-and low-quality-factor guided modes of the waveguides leads to a sharp Fano resonance at the optical communication wavelength of lambda = 1550 nm. Owing to the transparency of constituent dielectric layers in the near-infrared region, a sharp, low-loss Fano resonance appears in the reflection spectrum, which is favorable in sensing applications. The proposed sensor can detect small changes in the refractive index of the sensing medium as low as An = 0.001. The high sensitivity of a structure is promising in biochemical applications, such as measuring the refractive indices of organic solvents, the level of water content in ethanol and aqueous solutions, and blood glucose levels. The refractive index sensitivity is as high as SI = 999 RIU-1, and a figure of merit of FOM = 1000 is achieved. (c) 2023 Optica Publishing Group
Due to the intrinsic polarized emission property, polarized emissive materials with anisotropic nanostructures are expected to be potential substitutes for polarizers. Herein, by the template-assisted strategy, well-a...
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Due to the intrinsic polarized emission property, polarized emissive materials with anisotropic nanostructures are expected to be potential substitutes for polarizers. Herein, by the template-assisted strategy, well-aligned lead-free metal halide Cs3Cu2I5 nanowire (NW) arrays are fabricated by evaporating the precursor ink in the anodic aluminum oxide (AAO) for polarized emission. The Cs3Cu2I5/AAO composite film emits highly polarized light with a degree of polarization (DOP) of 0.50. Furthermore, by changing the molar ratio of CsI/CuI, the stability of Cs3Cu2I5 precursor inks is improved. Finally, an ultraviolet (UV) light-emitting diode (LED) is adopted to pump the composite film to achieve a blue LED device. The reported Cs3Cu2I5/AAO composite film with highly polarized light emissions will have great potential for polarized emission applications such as liquid crystal display backlights, waveguides, and lasers.
The corrosion of rebars will change the mechanical properties of the reinforced concrete structure, leading to the decline in the structural strength, which seriously threatens the safety and stability of buildings an...
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The corrosion of rebars will change the mechanical properties of the reinforced concrete structure, leading to the decline in the structural strength, which seriously threatens the safety and stability of buildings and power equipment foundations. Hence, it is of great significance to detect the internal corrosion of reinforced concrete structures. In this paper, a nondestructive detection method for detecting the corrosion in reinforced concrete structures based on microwave was proposed, and the corrosion state of rebar can be evaluated by the change of microwave information. Compared with other detection methods, microwave nondestructive detection has the advantages of low energy consumption, strong penetration, no contact, and small equipment volume and weight. In order to verify the effectiveness of the method, a microwave nondestructive detection simulation test platform was built and reinforced concrete test models with different corrosion lengths and depths were made. The influences of concrete parameters, the microwave frequency, and the lifting distance of the waveguide were analyzed. The frequency sweeping and moving scanning detection methods of the waveguide were carried out for the test models with different corrosion defects, and the changes of microwave S-parameters under different corrosion defects were obtained. The results show that when the waveguide is placed horizontally by the frequency sweeping detection method, the corrosion length detection effect of rebar is better. When the waveguide is placed vertically by the frequency sweeping detection method, the corrosion depth can be identified and the amplitude of transmission coefficient increases with the increase in the corrosion depth. The corrosion length of rebars can be identified quantitatively by the moving scanning detection method of the waveguide.
The existence of a shift-shift memory effect in square waveguides, whereby any translation of the input field induces translations in the output field in four symmetri-cal directions, has been previously observed by c...
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The existence of a shift-shift memory effect in square waveguides, whereby any translation of the input field induces translations in the output field in four symmetri-cal directions, has been previously observed by correlation measurements. Here we demonstrate that this memory effect is also observed in real space and can be put to use for imag-ing purposes. First, a focus is created at the output of a square-core multimode fiber, by wavefront shaping based on feedback from a guide-star. Then, because of the mem-ory effect, four symmetrical spots can be scanned at the fiber output by shifting the wavefront at the fiber input. We demonstrate that this property can be exploited to perform fluorescence imaging through the multimode fiber, without requiring the measurement of a transmission matrix. (c) 2023 Optica Publishing Group
We study experimentally the propagation of spin waves in waveguide structures consisting of two submicrometer-width yttrium iron garnet waveguides intersecting at a right angle. We show that, despite the significant s...
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We study experimentally the propagation of spin waves in waveguide structures consisting of two submicrometer-width yttrium iron garnet waveguides intersecting at a right angle. We show that, despite the significant spatial variations of the internal static magnet field and the in-plane anisotropy of the dispersion characteristics, the incident spin wave can efficiently pass through the microscopic cross-shaped structure and be transmitted into all its arms. This process depends strongly on the frequency of the wave and the orientation of the static magnetic field. By varying these parameters, one can achieve a controllable uniform or preferential transmission of the wave into different arms of the cross. Our results create the basis for the implementation of nanoscale magnonic networks to be used for the realization of complex non-Boolean data-processing schemes, including neuromorphic computing.
Terahertz modulation of chirped laser pulse intensity was achieved with phase-only spectral modulation. Preservation of this modulation during second harmonic generation together with almost 30% conversion efficiency ...
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Terahertz modulation of chirped laser pulse intensity was achieved with phase-only spectral modulation. Preservation of this modulation during second harmonic generation together with almost 30% conversion efficiency was demonstrated employing noncollinear frequency mixing of 60-mu J oppositely chirped laser pulses. (c) 2023 Optica Publishing Group
We analyze the guided modes in coupled waveguides made of negative-index materials without gain or loss. We show that it supports non-Hermitian phenomenon on the existence of guided mode versus geometric parameters of...
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We analyze the guided modes in coupled waveguides made of negative-index materials without gain or loss. We show that it supports non-Hermitian phenomenon on the existence of guided mode versus geometric parameters of the structure. The non-Hermitian effect is different from parity-time (PT) symmetry, and can be explained by a simple coupled-mode theory with an anti-PT symmetry. The existence of exceptional points and slow-light effect are discussed. This work highlights the potential of loss-free negative-index materials in the study of non-Hermitian optics.
Acoustic asymmetric focusing (AAF) has attracted widespread attention owing to its great potential in medical ultrasound. The recent development of acoustic metamaterials and metasurfaces has provided various concepts...
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Acoustic asymmetric focusing (AAF) has attracted widespread attention owing to its great potential in medical ultrasound. The recent development of acoustic metamaterials and metasurfaces has provided various concepts to achieve AAF systems. Generally, the previously demonstrated AAF lenses were limited to one-dimensional structures, leading to difficulties in practical applications. The realization of AAF in three-dimensional (3D) space based on a two-dimensional (2D) device still remains a challenge. Here, we experimentally and numerically study a 2D AAF lens based on mode converters composed of two pairs of phased unit cells I and II and a step waveguide. Based on the phase profile of sound focusing and the step waveguide of mode converters, we experimentally design and demonstrate a type of 2D AAF lens and observe acoustic focusing and asymmetric transmission simultaneously in 3D space under the excitation of the zero-order wave. Both the phenomena arise from the phase modulation of the lens and the cutoff frequency of the first-order wave for the step waveguide, respectively. The fractional bandwidth (the ratio of the bandwidth to the center frequency) of the lens can reach about 0.14. The proposed 2D AAF lens, as well as its associated mode converter, paves the way for the asymmetric manipulation of sound in 3D space that has potential applications in practical sound devices.
We present mode conversion in different magneto-optical photonic crystal (MOPC) waveguides. An odd-mode wave guide (OMW) and an even-mode waveguide (EMW) are designed by adjusting the geometric parameters of the wave ...
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We present mode conversion in different magneto-optical photonic crystal (MOPC) waveguides. An odd-mode wave guide (OMW) and an even-mode waveguide (EMW) are designed by adjusting the geometric parameters of the wave guide. These waveguides are constructed by adding a layer of yttrium-iron-garnet (YIG) rods with opposing magnetic fields between an MOPC and an Al2O3 photonic crystal (PC). Due to the coupling effect caused by the middle layer of YIG rods, the OMW (or EMW) only supports an odd (or even) mode within a single-mode frequency range. Simulation results demonstrate that they can convert other modes into odd or even modes, and there is almost no power loss during the conversion. Most importantly, they are robust against backscattering from perfect electric conductors (PECs) and point defects. Based on these properties, we propose a device that can efficiently separate the odd and even modes into different ports. These results offer a novel approach to controlling the transmission modes of waveguides, which facilitates the interconnection of diverse topological magneto-optical waveguides. & COPY;2023 Optica Publishing Group
The implementation of transverse mode, polarization, fre-quency, and other degrees of freedom (d.o.f.s) of photons is an important way to improve the capability of photonic cir-cuits. Here, a three-dimensional (3D) li...
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The implementation of transverse mode, polarization, fre-quency, and other degrees of freedom (d.o.f.s) of photons is an important way to improve the capability of photonic cir-cuits. Here, a three-dimensional (3D) linear polarized (LP) LP11 mode converter was designed and fabricated using a femtosecond laser direct writing (FsLDW) technique. The converter included multi-mode waveguides, symmetric Y splitters, and phase delaying waveguides, which were con-structed as different numbers and arrangements of circular cross section waveguides. Finally, the modes (LP11a and LP11b) were generated on-chip with a relatively low insertion loss (IL). The mode converter lays a foundation for on-chip high-order mode generation and conversion between differ-ent modes, and will play a significant role in mode coding and decoding of 3D photonic circuits.(c) 2023 Optica Publish-ing Group
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