The interaction between a very-high-frequency gravitational wave (VHFGW) and an electromagnetic wave (EMW) in a rectangular waveguide is discussed in the weak field limit. The background EMW is assumed to be initially...
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The interaction between a very-high-frequency gravitational wave (VHFGW) and an electromagnetic wave (EMW) in a rectangular waveguide is discussed in the weak field limit. The background EMW is assumed to be initially in the TE10 mode along the waveguide. It is then shown that a VHFGW, having the same frequency and direction of propagation of the EMW, induces through the waveguide a TE mode with a frequency doubled when compared to the original EMW frequency. In that respect, the GW acts similar to a non-linear medium, giving rise to a Second Harmonic Generation (SHG) effect. The interaction between a high-frequency gravitational wave and an electromagnetic wave in a waveguide is discussed in the linearized theory. It is shown that a gravitational wave, having the same frequency as the electromagnetic wave, gives rise to a Second Harmonic Generation effect, exciting a frequency-doubled electromagnetic mode in the waveguide. An estimate of such effect is ***
Terahertz (THz) band has promising applications in next-generation wireless communications and new sensing technologies. However, the on-chip transmission of THz waves will encounter strong scattering at sharp corner ...
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Terahertz (THz) band has promising applications in next-generation wireless communications and new sensing technologies. However, the on-chip transmission of THz waves will encounter strong scattering at sharp corner structures of waveguides. Recently, valley photonic crystals (VPC) offer new possibilities for high-fidelity transmission of THz wave along complex shape waveguides. The VPC-based waveguide overcomes defects and sharp corners, probably resulting in high-performance on-a-chip THz devices. The THz VPC with polymer materials can be easy and low-cost building with 3D printing technology. In this paper, the VPC waveguides operating around 300 GHz are constructed using honeycomb lattices on a thin polymer plate. The mirror symmetry is broken by proper air-circular apertures located in the honeycomb lattice with a nontrivial band structure. Then the influences on the band structure by the polymer refractive index ranging from 1.5 similar to 2.0, the thickness of the sheet, and the asymmetry of aperture diameters in the lattice are discussed. The transmission of straight, zigzag, and "omega"waveguides made of the polymer VPCs is simulated. The results demonstrate their high transmission efficiency and robustness to scattering from sharp bending above -10 dB with an 8-GHz bandgap. The proposed polymer VPC structure paves way for THz applications such as efficient beam splitters, low-loss complex-shaped waveguides, and robust delay lines.
In this work, we detail the integration of monolayer graphene electrodes in Silicon Nitride waveguides to achieve wavelength tuning. The numerical results show that wavelength shifts of a few hundred to several thousa...
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In this work, we detail the integration of monolayer graphene electrodes in Silicon Nitride waveguides to achieve wavelength tuning. The numerical results show that wavelength shifts of a few hundred to several thousand picometers shift can be obtained depending on the configuration. These results will help guide the design of graphene-based tunable optical devices operating in the near infrared range.
A judicious design of gain and loss leads to counterintuitive wave phenomena that are inaccessible by conservative systems. Notably, such designs can give rise to laser-absorber modes and anisotropic transmission reso...
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A judicious design of gain and loss leads to counterintuitive wave phenomena that are inaccessible by conservative systems. Notably, such designs can give rise to laser-absorber modes and anisotropic transmission resonances. Here, we analyze the emergence of these phenomena in an optical scatterer with sinusoid gain-loss modulation that is subjected to monochromatic oblique waves. We derive an analytical solution to the problem, with which we show how the scatterer parameters, and specifically the modulation phase and incident angle, constitute a real design space for these phenomena.
We explore special features of quantum light-matter interactions inside structured waveguides due to their finite bandwidth, band edges, and nontrivial topological properties. We model the waveguides as either a tight...
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We explore special features of quantum light-matter interactions inside structured waveguides due to their finite bandwidth, band edges, and nontrivial topological properties. We model the waveguides as either a tight-binding (TB) chain or a Su-Schrieffer-Heeger (SSH) chain. For unstructured waveguides with infinite bandwidth, the transmission and reflection coefficients of a side-coupled two-level emitter (2LE) are the same as the reflection and transmission coefficients of a direct-coupled 2LE. We show that this analogy breaks down for structured waveguides with finite bandwidth due to the appearance of Lamb shift only for the direct-coupled 2LE. We further predict a robust light-emitter coupling at zero collective decay width of a single giant 2LE (with two couplings at different points) near the band edges of the structured waveguides where topological features can be beneficial. Finally, we study single-photon dynamics in a heterojunction of a long TB and short SSH waveguide connected to a 2LE at the SSH end. We show the propagation of a photon from the excited emitter to the TB waveguide only when the SSH waveguide is in the topological phase. Thus, the heterojunction acts as a conditional propagation channel.
2D materials have manifested themselves as key components toward compact integrated circuits. Because of their capability to circumvent the diffraction limit, light manipulation using surface plasmon polaritons (SPPs)...
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2D materials have manifested themselves as key components toward compact integrated circuits. Because of their capability to circumvent the diffraction limit, light manipulation using surface plasmon polaritons (SPPs) is highly-valued. In this study, plasmonic photodetection using graphene as a 2D material is investigated. Non-scattering near-field detection of SPPs is implemented via monolayer graphene stacked under an SPP waveguide with a symmetric antenna. Energy conversion between radiation power and electrical signals is utilized for the photovoltaic and photoconductive processes of the gold-graphene interface and biased electrodes, measuring a maximum photoresponsivity of 29.2 mA W-1. The generated photocurrent is altered under the polarization state of the input light, producing a 400% contrast between the maximum and minimum signals. This result is universally applicable to all on-chip optoelectronic circuits. This study explores plasmonic photodetection using graphene, achieving non-scattering near-field detection of surface plasmon polaritons. The maximum photoresponsivity is 29.2 mA W-1, and the polarization state of input light produces a 400% contrast. This has potential applications in on-chip optoelectronic ***
Deep subwavelength highly confined and long-range optical propagation is vital for photonics integration. However, the performance of the guided mode could be improved by the trade-off between light confinement and lo...
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Deep subwavelength highly confined and long-range optical propagation is vital for photonics integration. However, the performance of the guided mode could be improved by the trade-off between light confinement and loss. Here, we demonstrate a high-performance hybrid waveguide consisting of a high-index nanowire separated from a linear array by a low-index dielectric gap. The array significantly achieves the plasmonic platform optimization based on a linear combination of few-layer graphene (FLG) and hexagonal boron nitride (hBN) layers. Through the hybridization of graphene plasmon polaritons and hyperbolic phonon polaritons mode, the resulting hybrid waveguide shows at least double times larger propagation distance and smaller mode area than the multilayer waveguide. Further, modulated by altering material configuration and geometric effects, the mode properties reveal that it is more flexible to adjust the optical transmission, along with a strong deep-subwavelength mode with low loss. Because of highly confined low-loss propagation, the hybrid waveguide is expected to be an excellent building block for various mid-infrared photonic integrated circuits. The present structure also has the potential to be extended to other FLGs, like magic-angle twisted bilayer graphene and trilayer graphene/hBN moire superlattice.
A periodically loaded waveguide composed of periodic discrete nonlinear gain and radiating elements supports a stable oscillation regime related to the presence of an exceptional point of degeneracy (EPD). After reach...
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The results of studies of metrological characteristics of primary power transducers of electromagnetic oscillations in waveguides, which have been in operation for more than 20 years, are presented. It is shown that w...
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Silica (SiO2) strip-loaded waveguides and Y-junctions on lithium niobate (LN) thin film were designed, fabricated and experimentally investigated. We first studied the optical confinement factor distribution in strip-...
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Silica (SiO2) strip-loaded waveguides and Y-junctions on lithium niobate (LN) thin film were designed, fabricated and experimentally investigated. We first studied the optical confinement factor distribution in strip-loaded waveguides. The Simulations showed that most of the power (>82%) was confined in the LN layer, and the dimensions of the SiO2 loading strip had a relatively small influence on the optical confinement factor distribution. The SiO2 film was deposited with the magnetron sputtering method. The deposited SiO2 layer approached stoichiometric SiO2, and a smooth surface was obtained. A group of waveguides with widths of 2-5 mu m were fabricated using lift-off technology. The 2 mu m-wide waveguide displayed low propagation losses of 0.2 dB/cm for the quasi-TE (q-TE) mode and 0.8 dB/cm for the quasi-TM (q-TM) mode at the wavelength of 1550 nm. Y-junctions with small sizes were designed and fabricated based on the low-loss waveguides. The transmission could reach 70-80%, and the splitting ratio maintained at a stable level near 1:1 for the Y-junctions S1 and S4. The low-loss strip-loaded waveguides and Y-junctions offer the possibility of combining SiO2 and LN materials for integrated optics. Additional high-performance photonic devices and circuits using this method are expected in the future.
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