Search

This paper aims to report a novel route to bursting by frequency switching for the slowly forced Duffing system. Typical fast-slow oscillations, i.e., the relaxation oscillations, can be observed in the slowly forced Duffing system. We find that when the slow forcing switches between two frequencies with a 2:1 ratio modulated by the velocity term, the equilibrium branches of the subsystems will alternate quickly. Accordingly, the trajectory will undergo fast transitions between the stable equilibrium branches of the subsystems. As a result, clusters of fast oscillations are created in the original relaxation oscillations. This way, the route to bursting by frequency switching is explained. Then, the effects of system parameters on the bursting are investigated. We show that whether the system produces slow motions or bursting is decided by the forcing amplitude, while the number of the fast oscillations in the clusters of bursting is dependent on the damping. Our results enrich the routes to bursting, and provide a reference for exploring bursting dynamics related to frequency switching modulated by the velocity term in other nonlinear dynamical systems. [ABSTRACT FROM AUTHOR]

A triple-band absorber with typical three-layer structure is proposed in the terahertz region. Pattern layer consists of two concentric rings with different sizes, and photosensitive silicon is put into the symmetric double gaps of the inner one. The conductivity of silicon is taken as one regulating method. Under the action of a suitable pump laser, dynamic switching of the resonance frequency is realized through manipulating the conducting state of photosensitive silicon. Concretely, without excitation, there are three resonance absorption peaks at 1.000 THz (f1), 1.550 THz (f2), and 2.090 THz (f3). While pumped by an excitation laser, peak f2 generates a red shift to 1.500 THz and peak f3 to 2.075 THz. Taking polarization angle of the incident THz wave as another regulating method, we can modulate the absorption amplitude with or without excitation by device rotation. Thus, we obtain the characteristics of frequency switching and amplitude modulation simultaneously. It is even more crucial that continuous modulation of the absorption amplitude is achieved at each fixed resonant point without any frequency shift. The maximum value of amplitude modulation depths is up to 100%. The proposed device provides a new perspective to explore future multifunctional terahertz absorbers. [ABSTRACT FROM AUTHOR]

In this study, the impact on the dielectric properties of 8CB with the dispersion of TiO2, ZnO, and methylene blue (0% to 5%) is examined. Employing capacitance–voltage (C–V) measurements across frequencies ranging from 10 kHz to 2 MHz, we explore the combined effects of dispersed photoactive nanoparticles and mono/polymeric materials like MB. Our investigation provides novel insights into the nuanced variations induced by transition-metal oxide loaded 8CB, highlighting the role of their oxidation states, and elucidates the influence of larger photoactive monomers on 8CB's dielectric polarizability. The study found that the dielectric anisotropy was strongly influenced by frequency and doping, changing sign at a critical frequency. Our work represents the first comparative analysis incorporating these oxides alongside photoactive materials like MB. • Explores effect of 0 to 5% ZnO, TiO 2 and MB doping on the dielectric anisotropy of 8CB liquid crystal. • Capacitance–voltage measurements of dielectric anisotropy over 200 kHz to 2 MHz. • Dielectric anisotropy changes sign from positive to negative for all dopants, highest for MB. • Dopant introduces optical properties and enhances dielectric permittivity of 8CB. [ABSTRACT FROM AUTHOR]