Thickness-Dependent Gilbert Damping and Soft Magnetism in Metal/Co-Fe-B/Metal Sandwich Structure.

The achievement of the low Gilbert damping parameter in spin dynamic modulation is attractive for spintronic devices with low energy consumption and high speed. Metallic ferromagnetic alloy Co-Fe-B is a possible candidate due to its high compatibility with spintronic technologies. Here, we report thickness-dependent damping and soft magnetism in Co-Fe-B films sandwiched between two non-magnetic layers with Co-Fe-B films up to 50 nm thick.

Inverse-designed ultra-compact multi-channel and multi-mode waveguide crossings.

In this work, we use the inverse design method to design three-channel and four-channel dual-mode waveguide crossings with the design regions of 4.32 µm-wide regular hexagon and 6.68 µm-wide regular octagon, respectively.

Three-dimensional mode-division multiplexing system.

Blindly increasing the channels of the mode (de)multiplexer on the single-layer chip can cause the device structure to be too complex to optimize. The three-dimensional (3D) mode division multiplexing (MDM) technology is a potential solution to extend the data capacity of the photonic integrated circuit by assembling the simple devices in the 3D space. In our work, we propose a 16 × 16 3D MDM system with a compact footprint of about 100 µm × 5.

Multifunctional Plasmon-Induced Transparency Devices Based on Hybrid Metamaterial-Waveguide Systems.

In this paper, we design a multifunctional micro-nano device with a hybrid metamaterial-waveguide system, which leads to a triple plasmon-induced transparency (PIT). The formation mechanisms of the three transparent peaks have their own unique characteristics. First, PIT-I can be switched into the BIC (Friedrich-Wintge bound state in continuum), and the quality factors (Q-factors) of the transparency window of PIT-I are increased during the process.

Continuously tunable metasurfaces controlled by single electrode uniform bias-voltage based on nonuniform periodic rectangular graphene arrays.

Metasurfaces, the two-dimensional artificial metamaterials, have attracted intensive attention due to their abnormal ability to manipulate the electromagnetic wave. Although there have been considerable efforts to design and fabricate beam steering devices, continuously tunable devices with a uniform bias-voltage have not been achieved. Finding new ways to realize more convenient and simpler wavefront modulation of light still requires research efforts.

Double Electromagnetically Induced Transparency and Its Slow Light Application Based On a Guided-Mode Resonance Grating Cascade Structure.

In recent years, the achievement of the electromagnetically induced transparency (EIT) effect based on the guided-mode resonance (GMR) effect has attracted extensive attention. However, few works have achieved a double EIT-like effect using this method. In this paper, we numerically achieve a double EIT-like effect in a GMR system with a three-layer silicon nitride waveguide grating structure (WGS), using the multi-level atomic system model for theoretical explanation.

Asymmetric dielectric grating on metallic film enabled dual- and narrow-band absorbers.

We investigated a mid-infrared (mid-IR) dual-band absorber consisting of a continuous gold film coated with an asymmetric silicon grating. In each unit cell of the grating, there are three unequally spaced silicon strips. Numerical results reveal that the (+1, -1) planar surface plasmon polariton (SPP) waves excited by the transverse-magnetic (TM) incidence can be coupled with different Fabry-Pérot (FP) resonances and the resonant energy is dissipated to the ohmic loss.

All-optical switch and logic gates based on hybrid silicon-GeSbTe metasurfaces.

We numerically propose a hybrid metasurface (MS) to realize all-optical switch and logic gates in the shortwave infrared (SWIR) band. Such MS consists of one silicon rod and one GeSbTe (GST) rod pair. Utilizing the transition from an amorphous state to a crystalline state of GST, such MS can produce an electromagnetically induced transparency (EIT) analogue with active control.

Suppressing the unwanted resonance mode in a metal-insulator-metal structure using fine-structured gratings.

We numerically present that suppressing the unwanted resonance mode in a metal-insulator-metal (MIM) structure can be achieved by using a fine-structured gold grating. In each period of the grating, a sub-grating consisting of multiple gold strips is used. Investigations on a high quality-factor (Q-factor) MIM structure with the grating and usual gratings are carried out.

High quality factor electromagnetically induced transparency-like effect in coupled guided-mode resonant systems.

We numerically study a dielectric coupled guided-mode resonant (GMR) system, which includes two silicon (Si) grating waveguide layers (GWLs) stacked on CaF substrates. It is confirmed that the coupling between the top and bottom GMR modes starts once a Fabry-Perot (F-P) resonator is introduced, and electromagnetically induced transparency (EIT)-like spectral responses occur in the coupled GMR systems. A very narrow transparency window with a high-quality (Q) factor EIT-like effect of up to 288,892 was demonstrated.

Control of resonance mode using a fine-structured grating: toward a high resolving power filter.

A band-stop filter with high resolving power is designed for mid-infrared spectroscopic sensing and imaging applications. By utilizing a truncated grating consisting of multiple gold nanowires in each unit cell of the periodic structure, compression of the stop bandwidth and improvement of the resonance extinction are realized simultaneously. It shows only a single stop band at ∼4.

Active control of broadband plasmon-induced transparency in a terahertz hybrid metal-graphene metamaterial.

A hybrid metal-graphene metamaterial (MM) is reported to achieve active control of broadband plasmon-induced transparency (PIT) in the THz region. The unit cell consists of one cut wire (CW), four U-shaped resonators (USRs) and monolayer graphene sheets under the USRs. near-field coupling, broadband PIT can be produced through the interference between different modes.

Active Enhancement of Slow Light Based on Plasmon-Induced Transparency with Gain Materials.

As a plasmonic analogue of electromagnetically induced transparency (EIT), plasmon-induced transparency (PIT) has drawn more attention due to its potential of realizing on-chip sensing, slow light and nonlinear effect enhancement. However, the performance of a plasmonic system is always limited by the metal ohmic loss. Here, we numerically report a PIT system with gain materials based on plasmonic metal-insulator-metal waveguide.

Plasmonic Refractive Index Sensor with High Figure of Merit Based on Concentric-Rings Resonator.

A plasmonic refractive index (RI) sensor based on metal-insulator-metal (MIM) waveguide coupled with concentric double rings resonator (CDRR) is proposed and investigated numerically. Utilizing the novel supermodes of the CDRR, the FWHM of the resonant wavelength can be modulated, and a sensitivity of 1060 nm/RIU with high figure of merit (FOM) 203.8 is realized in the near-infrared region.

Ultra-compact beam splitter and filter based on a graphene plasmon waveguide.

This paper presents a sheet of graphene-ribbon waveguide as a simple and ultra-compact splitter and filter in the mid-infrared waveband. The central wavelength of the graphene surface plasmons (GSPs) and the coupling intensity of this splitter can be tuned by changing the physical parameters, such as the chemical potential, the width of the waveguide, the gap between neighboring graphene ribbons, the refractive index of the substrate, the carrier relaxation time, etc. The effects of these parameters on GSP waves and beam-splitter specifications are numerically depicted based on the finite-difference time-domain method.

Rapid Focused Ion Beam Milling Based Fabrication of Plasmonic Nanoparticles and Assemblies via "Sketch and Peel" Strategy.

Focused ion beam (FIB) milling is a versatile maskless and resistless patterning technique and has been widely used for the fabrication of inverse plasmonic structures such as nanoholes and nanoslits for various applications. However, due to its subtractive milling nature, it is an impractical method to fabricate isolated plasmonic nanoparticles and assemblies which are more commonly adopted in applications. In this work, we propose and demonstrate an approach to reliably and rapidly define plasmonic nanoparticles and their assemblies using FIB milling via a simple "sketch and peel" strategy.