Power Transport Theorem Based Decoupling Mode Theory for Wave-Port-Fed Transmitting Antennas

Employing the work-energy principle based physical interpretation for characteristic mode theories (CMTs), it is exposed that: strictly speaking, the existing CMTs are the modal analysis theories for incident-field-driven scattering objects and lumped-port-driven transmitting antennas, but not for wave-port-fed transmitting antennas, so they cannot provide an exact modal analysis to wave-port-fed antennas. This paper focuses on establishing an effective modal analysis theory for wave-port-fed antennas. Power transport theorem (PTT), which governs the transport process of the power-flow passing through wave-port-fed antenna, is derived. It is found out that the input power contained in PTT is the source to sustain a stationary power transport. Under PTT framework, a novel modal analysis theory — decoupling mode theory (DMT) — is established for the antenna. By orthogonalizing input power operator (IPO), the PTT-based DMT can construct a set of energy-decoupled modes (DMs) for the antenna. A novel concept of "electric-magnetic energy-decoupling factor" / "electric-magnetic phase-mismatching factor" is introduced for quantifying the coupling/matching degree between modal electric field and modal magnetic field. A field-based definition for modal input impedance and admittance is proposed as an alternative for the conventional circuit-based definition. Three somewhat different but not contradictory physical meanings of modal significance (MS) are summarized.

Power Transport Theorem Based Decoupling Mode Theory for Wave-Port-Fed Transmitting Antennas

Employing the work-energy principle based physical interpretation for characteristic mode theories (CMTs), it is exposed that: strictly speaking, the existing CMTs are the modal analysis theories for incident-field-driven scattering objects and lumped-port-driven transmitting antennas, but not for wave-port-fed transmitting antennas, so they cannot provide an exact modal analysis to wave-port-fed antennas. This paper focuses on establishing an effective modal analysis theory for wave-port-fed antennas. Power transport theorem (PTT), which governs the transport process of the power-flow passing through wave-port-fed antenna, is derived. It is found out that the input power contained in PTT is the source to sustain a stationary power transport. Under PTT framework, a novel modal analysis theory — decoupling mode theory (DMT) — is established for the antenna. By orthogonalizing input power operator (IPO), the PTT-based DMT can construct a set of energy-decoupled modes (DMs) for the antenna. A novel concept of "electric-magnetic energy-decoupling factor" / "electric-magnetic phase-mismatching factor" is introduced for quantifying the coupling/matching degree between modal electric field and modal magnetic field. A field-based definition for modal input impedance and admittance is proposed as an alternative for the conventional circuit-based definition. Three somewhat different but not contradictory physical meanings of modal significance (MS) are summarized.

Dynamic Mechanical Cue Facilitate Collective Responses of Crowded Cell Population

Collective cell behavior is essential for tissue growth, development and function, e.g. heartbeat1, immune responses2 and cerebral consciousness3. In recent years, studies on population cells uncover that collective behavior emerges in both inter- and intra-cellular activities, e.g. synchronized signal cascade4, and collective migration5. As the movement and shape transition of cells within the crowded environment of biological tissue can generate mechanical cues at the cell-cell interface, which may affect the signaling cascade6,7, we suspect that the inter- and intra-cellular collective behavior interplay with one another and cooperatively regulate life machinery. To verify our hypothesis, we study the collective responses of fibroblasts in a confluent cell monolayer (CCM). Our results demonstrate that cells in CCM show distinctive behavior as compared to the stand-alone (SA) cells, suggesting effect of inter-cellular interactions. Upon periodic TNF-α stimulation, collective behavior emerges simultaneously in NF-κB signaling cascade and nuclear shape fluctuations in CCM but not SA cells. We then model the inter-cellular interactions in CCM using a customized microfluidic device, and discover a feedback loop intrinsic to CCM, in which dynamic mechanical cues and mechano-signaling act as link connecting the inter- and intra-cellular collective activities. We found that mechano-signaling triggered by the dynamic mechanical cues causes collective nuclear shape fluctuation (NSF), which subsequently facilitates the collective behavior in NF-κB dynamics. Furthermore, our studies reveal that regardless of the input TNF-α periodicity, cellular responses of single fibroblasts are elevated when the dynamic mechanical cues synergize with the chemical inputs, and inhibited when there is phase-mismatching. We, therefore, postulate that besides the biological significance of mechano-signaling in regulating collective cell responses, the induction of dynamic mechanical cues to human body may be a potential therapeutic approach, allowing us to regulate the action of single cells to achieve optimal tissue performance.

Atto-Joule, high-speed, low-loss plasmonic modulator based on adiabatic coupled waveguides

In atomic multi-level systems, adiabatic elimination (AE) is a method used to minimize complicity of the system by eliminating irrelevant and strongly coupled levels by detuning them from one another. Such a three-level system, for instance, can be mapped onto physically in the form of a three-waveguide system. Actively detuning the coupling strength between the respective waveguide modes allows modulating light to propagate through the device, as proposed here. The outer waveguides act as an effective two-photonic-mode system similar to ground and excited states of a three-level atomic system, while the center waveguide is partially plasmonic. In AE regime, the amplitude of the middle waveguide oscillates much faster when compared to the outer waveguides leading to a vanishing field build up. As a result, the plasmonic intermediate waveguide becomes a “dark state,” hence nearly zero decibel insertion loss is expected with modulation depth (extinction ratio) exceeding 25 dB. Here, the modulation mechanism relies on switching this waveguide system from a critical coupling regime to AE condition via electrostatically tuning the free-carrier concentration and hence the optical index of a thin indium thin oxide (ITO) layer resides in the plasmonic center waveguide. This alters the effective coupling length and the phase mismatching condition thus modulating in each of its outer waveguides. Our results also promise a power consumption as low as 49.74aJ/bit. Besides, we expected a modulation speed of 160 GHz reaching to millimeter wave range applications. Such anticipated performance is a direct result of both the unity-strong tunability of the plasmonic optical mode in conjunction with utilizing ultra-sensitive modal coupling between the critically coupled and the AE regimes. When taken together, this new class of modulators paves the way for next generation both for energy and speed conscience optical short-reach communication such as those found in interconnects.