Active Ultrahigh‐Q (0.2 × 10⁶) THz Topological Cavities on a Chip

Abstract

ever-increasing demand for higher data transfer rates in wired and wireless communication links. The exponential growth in data rates has pushed the carrier frequencies toward the higher spectral region, the terahertz (THz) band. The availability of ultrahigh bandwidths in the THz region (0.1-10 THz) allows achievement of terabits per second connectivity, [1] making it ideal for sixth-generation (6G) communication. However, with the emergence of 6G networks, the development of efficient on-chip communication with low loss and active control is crucial to handle and process the massive volume of data transmitted using THz carrier frequencies. The existing solutions for high-speed on-chip interconnects, including copper-based electrical interconnects (EIs), [2] suffer from limited bandwidth, and optical interconnects (OIs) [3] possess integration complexity and electronic-to-optical (EO/OE) conversion losses. To circumvent the existing performance gaps (in terms of bandwidths, energy efficiency, and system simplicity) of on-chip interconnects, THz interconnects [4,5] offer a potential route by leveraging the advantages of both the electronic and photonic worlds. However, scaling carrier frequencies up to sub-THz and beyond requires further innovation toward on-chip photonic solutions to support higher radio-frequency (RF) electronics Rapid scaling of semiconductor devices has led to an increase in the number of processor cores and integrated functionalities onto a single chip to support the growing demands of high-speed and large-volume consumer electronics. To meet this burgeoning demand, an improved interconnect capacity in terms of bandwidth density and active tunability is required for enhanced throughput and energy efficiency. Low-loss terahertz silicon interconnects with larger bandwidth offer a solution for the existing inter-/intrachip bandwidth density and energy-efficiency bottleneck. Here, a low-loss terahertz topological interconnect-cavity system is presented that can actively route signals through sharp bends, by critically coupling to a topological cavity with an ultrahigh-quality (Q) factor of 0.2 × 10 6 . The topologically protected large Q factor cavity enables energy-efficient optical control showing 60 dB modulation. Dynamic control is further demonstrated of the critical coupling between the topological interconnect-cavity for on-chip active tailoring of the cavity resonance linewidth, frequency, and modulation through complete suppression of the back reflection. The silicon topological cavity is complementary metal-oxide-semiconductor (CMOS)-compatible and highly desirable for hybrid electronic-photonic technologies for sixth (6G) generation terahertz communication devices. Ultrahigh-Q cavity also paves the path for designing ultrasensitive topological sensors, terahertz topological integrated circuits, and nonlinear topological photonic devices.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adma.202202370.

A high Q-factor dual-band terahertz metamaterial absorber and its sensing characteristics

“…43,44 Moreover, terahertz sensors using diverse novel materials have also been investigated in depth, including lead iodide (PbI 2 ) for ultrafast all-optical switching, 45 polymethyl methacrylate (PMMA) for molecular vibrational sensing, 46 perovskites for flexible devices, 47 and valley photonic crystals for ultrasensitive topological sensing. 48 In addition to the familiar sensors that judged by the amplitude shift, some sensors rely on phase change characteristics, which also have potential applications in biosensing. [49][50][51] In this paper, we propose a dual-band metamaterial absorber in terahertz frequencies with a periodically patterned metal structure on the top of a silicon wafer.…”

Active Energy‐Efficient Terahertz Metasurfaces Based on Enhanced In‐Plane Electric Field Density

“…[ 4–7 ] Photonics is one of the prominent areas where light‐matter interactions are enhanced using resonant cavities, which are used in lasing, spectroscopy, and sensing applications. [ 8–11 ] Electromagnetic confinement in such cavities play an instrumental role in probing and tuning material properties, which requires strong coupling between light and matter. [ 12–14 ] Large field confinement with an effectively low modal area/volume has profound applications in the area of near‐field microscopy, nonlinear spectroscopy, and sub‐wavelength imaging.…”

“…[4][5][6][7] Photonics is one of the prominent areas where light-matter interactions are enhanced using resonant cavities, which are used in lasing, spectroscopy, and sensing applications. [8][9][10][11] Electromagnetic confinement in such cavities play an instrumental role in probing and tuning material properties, which requires strong where E xy is the in-plane electric field strength of resonator on the top of the substrate surface (S) in the unit cell. S eff is the effective mode area of electromagnetic confinement in the unit cell, while ρ xy is the in-plane electric field density within S eff .…”

Dynamic switching between bound states in the continuum (BIC) and quasi-BIC based on a Dirac semimetal terahertz metasurface

“…High-quality-factor (Q-factor) optical resonators are in considerable demand for photonic systems, wherein such resonance-induced physical phenomena have a wide range of applications, such as enhanced optical nonlinear effects 1,2 and enhanced light emission, 3 in addition to the implementation of ultra-narrowband filtering 4,5 and ultra-sensitive sensing, 6,7 and achieving high Q-factor on artificial micro-nano structures has become a research hotspot. [8][9][10][11] Bound states in the continuum (BICs) are a unique type of bound-state waves located in the radiation region. 12 Although they coexist with the extended state in the continuum, they are completely bound and decoupled from radiation waves without external radiation and are theoretically capable of achieving infinitely high Q-factors.…”