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Terahertz (THz) detector has great potential for use in imaging, spectroscopy, and communications due to its fascinating interactions between radiation and matter. However, current THz detection devices have limitations in sensitivity, operating frequency range, and bulky footprint. While recent ferroelectric-integrated graphene plasmonic devices show promise in overcoming these limitations, they are not yet extended to the THz range. Here, we propose a wavelength-sensitive terahertz detector that uses a single layer graphene integrated onto the ferroelectric thin film with patterned polarization domains. This device works at room temperature, with high responsivity and detectivity by coupling graphene plasmons with THz frequencies through spatial modulation of carrier behaviors using ferroelectric polarization, without requiring additional local electrodes. By reconfiguring an interweaving squared ferroelectric domain array with alternating upward and downward polarizations to highly confine graphene surface plasmon polaritons, our device achieves an ultrahigh responsivity of 1717 A W-1 and a normalized detectivity of 1.07*10^13 Jones at a resonance frequency of 6.30 THz and a 0.3 V bias voltage. We also show that the device makes possible for spectrum reconstruction application of portable spectrometer combining the mathematical algorithms., Comment: 17 pages, 5 figures

The quest for realizing and manipulating ever smaller man-made movable structures and dynamical machines has spurred tremendous endeavors, led to important discoveries, and inspired researchers to venture to new grounds. Scientific feats and technological milestones of miniaturization of mechanical structures have been widely accomplished by advances in machining and sculpturing ever shrinking features out of bulk materials such as silicon. With the flourishing multidisciplinary field of low-dimensional nanomaterials, including one-dimensional (1D) nanowires/nanotubes, and two-dimensional (2D) atomic layers such as graphene/phosphorene, growing interests and sustained efforts have been devoted to creating mechanical devices toward the ultimate limit of miniaturization--genuinely down to the molecular or even atomic scale. These ultrasmall movable structures, particularly nanomechanical resonators that exploit the vibratory motion in these 1D and 2D nano-to-atomic-scale structures, offer exceptional device-level attributes, such as ultralow mass, ultrawide frequency tuning range, broad dynamic range, and ultralow power consumption, thus holding strong promises for both fundamental studies and engineering applications. In this Review, we offer a comprehensive overview and summary of this vibrant field, present the state-of-the-art devices and evaluate their specifications and performance, outline important achievements, and postulate future directions for studying these miniscule yet intriguing molecular-scale machines., Comment: 41 pages, 30 figures

In this paper, we propose two new nonblocking properties of automata as quantitative measures of maximal distances to marker states. The first property, called {\em quantitative nonblockingness}, captures the practical requirement that at least one of the marker states (representing e.g. task completion) be reachable within a prescribed number of steps from any non-marker state and following any trajectory of the system. The second property, called {\em heterogeneously quantitative nonblockingness}, distinguishes individual marker states and requires that each marker state be reached within a given bounded number of steps from any other state and following any trajectory of the system. Accordingly, we formulate two new problems of quantitatively nonblocking supervisory control and heterogeneously quantitatively nonblocking supervisory control, and characterize their solvabilities in terms of new concepts of quantitative language completability and heterogeneously quantitative language completability, respectively. It is proved that there exists the unique supremal (heterogeneously) quantitatively completable sublanguage of a given language, and we develop effective algorithms to compute the supremal sublanguages. Finally, combining with the algorithm of computing the supremal controllable sublanguage, we design algorithms to compute the maximally permissive solutions to the formulated (heterogeneously) quantitatively nonblocking supervisory control problems.