1,721,336 research outputs found
Replication Data for: Toroidal versus Fano resonances in high Q planar THz metamaterials
No full textRadiative losses are crucial in optimizing the performance of metamaterial based devices across the electromagnetic spectrum. Introducing structural asymmetry in meta-atom design leads to the excitation of sharp Fano resonances with reduced radiative losses. However, at larger asymmetries, the Fano resonance becomes highly radiative which results in the broadening of the asymmetric line shaped resonances. Here, we experimentally demonstrate a scheme to couple mirrored asymmetric Fano resonators through interaction of anti-aligned magnetic dipoles which results in a strong toroidal resonance in two-dimensional planar metasurface. The quality (Q) factor and the figure of merit of the toroidal dipolar mode is significantly higher than the Fano resonance. Moreover, we discover that the exponential decay of the Q factor of toroidal resonance mode occurs at half the rate of that in the Fano resonance as the asymmetry of the system is enhanced which indicates significant tailoring and the suppression of the radiative loss channel in the toroidal configuration. The weakly-radiative toroidal resonance in planar metamaterials offers the potential for applications in terahertz and optical sensing, spectroscopy, narrow-band filtering and large modulation
Replication Data for: 150 Gbps THz Chipscale Topological Photonic Diplexer
No full textPhotonic diplexers are being widely investigated for high data transfer rates in on-chip communication. However, dividing the available spectrum into non-overlapping multicarrier frequency sub-bands has remained a challenge in designing frequency-selective time-invariant channels. Here, we report an on-chip topological diplexer exhibiting terahertz frequency band filtering through Klein tunnelling of topological edge modes. The silicon topological diplexer chip facilitates two high-speed channels with quadrature amplitude modulation (QAM) over a broad bandwidth of 12.5 GHz each. These channels operate at carrier frequencies of 305 GHz and 321.6 GHz, achieving a combined diplexer capacity of 150 Gbit/s. To ensure minimal interference between adjacent channels, a guard band is implemented. Topologically protected edge modes suppress the frequency selective fading of the broadband signals and hold promise for diverse integrated photonic applications spanning terahertz and telecommunication realms, including the design of lossless topological multiplexers, interconnects, antennas, and modulators for the sixth to X generation (6G to XG) wireless
Replication Data for: Terahertz Sensing with Optimized Q/Veff Metasurface Cavities
No full textConfinement of electromagnetic radiation in a subwavelength cavity is an important platform for strong light–matter interaction as it enables efficient design of photonic switches, modulators, and ultrasensitive sensors. Metallic metasurfaces consist of an array of planar cavities that allow easy access to confined electromagnetic modes on the surface. However, the radiative and nonradiative losses limit the quality factor (Q) of the resonantly confined mode. Therefore, metasurface designs with effectively low mode volume (Veff) cavities become extremely important for enhancing the photonic density of states. Here, a symmetric Lorentzian resonant metasurface with lower Veff is demonstrated as compared to asymmetric Fano resonators. Lower mode volume and optimized Q/Veff metasurfaces reveal enhanced sensitivity for ultrathin analyte overlayers deposited on metasurfaces signaling enhanced light–matter interaction. Such metasurfaces with tightly confined electromagnetic modes could find wide range of applications in the development of terahertz metadevices including ultrasensitive sensors, bandpass filters, and energy-efficient modulators
Replication Data for: 327 Gbps THz Silicon Photonic Interconnect with Sub-λ Bends
No full textMiniaturized photonic devices at the terahertz (THz) band are envisioned to bring significant enhancement to data transfer capacity and integration density for computing and future wireless communications. Broadband silicon waveguiding technology has continuously matured to advance low-loss platforms for integrated solutions. However, challenges are faced in realizing compact waveguiding platforms with different degrees of bends due to bend induced losses and mode distortion. Here, we demonstrate multiple bend incorporated photonic crystal waveguide platform for multi-carrier on-chip transmission. Our silicon interconnect device exhibits optimized bending radius to the free space wavelength ratio of 0.74, without signal distortion and transmission bandwidth of 90 GHz, representing 25.4% fractional bandwidth at 355 GHz. The broadband waveguide interconnect enables an aggregate data transfer rate of 327 Gbps by sending the complex modulated data over multiple carriers. This work augments the development of THz photonic integrated circuit (TPIC) for the future generations of on-chip high data-rate interconnect and wireless communication, ranging from the sixth to X generation (6G to XG)
Replication Data for: A Toroidal Metamaterial Switch
No full textToroidal dipole is a localized electromagnetic excitation that plays an important role in determining the fundamental properties of matter due to its unique potential to excite nearly non-radiating charge-current configuration. Toroidal dipoles were recently discovered in metamaterial systems where it has been shown that these dipoles manifest as poloidal currents on the surface of a torus and are distinctly different from the traditional electric and magnetic dipoles. Here, we demonstrate an active toroidal metamaterial switch in which the toroidal dipole could be dynamically switched to the fundamental electric dipole or magnetic dipole, through selective inclusion of active elements in a hybrid metamolecule design. Active switching of non-radiating toroidal configuration into highly radiating electric and magnetic dipoles can have significant impact in controlling the electromagnetic excitations in free space and matter that could have potential applications in designing efficient lasers, sensors, filters, and modulators
Replication Data for: Electrically Tunable Topological Notch Filter for THz Integrated Photonics
No full textElectromagnetic filtering is essential for emerging integrated photonic technologies and widely adaptable processing of high-bandwidth signals. Conventional electro-optic modulator-based photonic approach for signal filtering at microwave frequencies could not be implemented at terahertz (THz) frequencies due to the unavailability of the THz signal-driven optical modulator. Here, we demonstrate an electrically tunable on-chip THz photonic notch filter based on the topologically protected valley hall waveguide-cavity platform. Our device shows a significantly large notch suppression depth of more than 20 dB with a return loss of 13 dB at in the entire tuning range of notch frequency. The feedback control circuit enabled precise control of the notch frequency shift with a minimum step size of 7 MHz. Our work extends the application of topological photonic crystals in developing THz integrated photonic devices for transformative technologies, including sixth generation (6G) communication and high-resolution spectral sensing
Replication Data for: Sensing with toroidal metamaterial
No full textLocalized electromagnetic excitation in the form of toroidal dipoles has recently been observed in metamaterial systems. The origin of the toroidal dipole lies in the currents flowing on the surface of a torus. Thus, the exotic toroidal excitations play an important role in determining the optical properties of a system. Toroidal dipoles also contribute towards enabling high quality factor subwavelength resonances in metamaterial systems which could be an excellent platform for probing the light matter interaction. Here, we demonstrate sensing with toroidal resonance in a two-dimensional terahertz metamaterial in which a pair of mirrored asymmetric Fano resonators possess anti-aligned magnetic moments at electromagnetic resonance that gives rise to a toroidal dipole. Our proof of concept demonstration opens up an avenue to explore the interaction of matter with toroidal multipoles that could have strong applications in sensing of dielectrics and biomolecules
Replication Data for: Sharp toroidal resonances in planar terahertz metasurfaces
No full textToroidal dipole excitation in planar metasurface provides an alternate approach towards excitation of high Q resonances. In contrast to conventional multipoles, toroidal dipole interaction strength depends on the time derivative of the surrounding electric field. A characteristic feature of a toroidal dipole is tightly confined loops of oscillating magnetic field that curl around the fictitious arrow of a toroidal dipole vector in 3D space
Replication Data for: YBa2Cu3O7 as a high-temperature superinductor
No full textThe magnetic behavior of type-II superconductors is explained by a quantum vortex with a supercurrent encircling a coherence-length sized core. In a superconducting film with thickness t < λL, the vortex field decays slowly as 1/r2, extending to the Pearl length =22, known as the Pearl vortex, rather than diverging as log(1/r) and decaying with London penetration depth, λL, as in Abrikosov vortex. However, the effect of Pearl vortex on large enhancement of kinetic inductance had not been fully explored. Here, we discovered Pearl inductance, an additional form of kinetic inductance arising from geometrical structuring of high-Tc YBCO superconductor thin films (Tc~81K) at the scale. This results from extension of vortex screening supercurrents from λL to 14λL in an ultrathin meta-atom of thickness λL/7, enabling terahertz superinductance. Our device show impedance exceeding the quantum resistance limit ≈6.47 Ω by 33%, offering possibilities for cutting-edge electronic, photonic, and quantum devices
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