ABSTRACT
At present, the proposed microwave power detection systems cannot provide a high dynamic detection range and measurement sensitivity at the same time. Additionally, the frequency band of these detection systems cannot cover the 5G-communication frequency band. In this work, a novel microwave power detection system is proposed to measure the power of the 5G-communication frequency band. The detection system is composed of a signal receiving module, a power detection module and a data processing module. Experiments show that the detection frequency band of this system ranges from 1.4 GHz to 5.3 GHz, the dynamic measurement range is 70 dB, the minimum detection power is -68 dBm, and the sensitivity is 22.3 mV/dBm. Compared with other detection systems, the performance of this detection system in the 5G-communication frequency band is significantly improved. Therefore, this microwave power detection system has certain reference significance and application value in the microwave signal detection of 5G communication systems.
ABSTRACT
The ability to control, manipulate, and read out nanomechanical resonators is of great significance for many applications. In this work, we start by constructing a nonlinear dynamic model that is deduced from the fundamental beam-photon-electron interaction and energy band theories, with the aim of describing a complicated cavity-free optomechanical coupling process. Based on the model established, we first reveal the manipulation of a resonator's response, including softening and hardening effects due to laser injection. By driving the laser parametrically, we comprehensively investigate the control of the resonator's dynamics, in particular, in the nonlinear regime. It is found that both the laser power and frequency can be used to directly manipulate the NEMS resonator's dynamics, e.g., by amplitude amplification, periodicity changes, and periodic-chaotic state conversion. We then provide bifurcation diagrams, which evidence a deterministic evolution of dynamics. Finally, we perform a special study of the control of chaotic states of the nanomechanical resonator using laser parametric driving. The maximal Lyapunov exponents together with time series calculation show that the chaotic states can be controlled at a few specific frequency points of the injecting laser. This work not only provides guidance for using lasers to control nanoscale resonators, but also sheds light on the exploration of novel applications based on nonlinear NEMS resonators.
ABSTRACT
Generating various laser sources is important in the communication systems. We propose an approach that uses a mechanical resonator coupled with the optical fibre system to produce periodic and chaotic optical signals. The resonator is structured in such a way that the nonlinear oscillation occurs conveniently. The mechanical apparatus in the configuration is the well known resonating system featured by the negative stiffness. The mechanical resonance is converted to reflected optical signal with the same dynamic properties as the mechanical oscillation, subsequently interacting with the optical signal within the optical fibre. The optical radiative force on the mechanical structure is also considered in the analysis. The coupled electro-optomechanical system has been analysed, and results show that the mechanical resonator has the capability to control the dynamics of the optical signal precisely. The system will have potential applications in tunable laser sources.
ABSTRACT
In this work, nonlinear dynamics of silicon nanowire resonator considering nonlocal effect has been investigated. For the first time, dynamical parameters (e.g., resonant frequency, Duffing coefficient, and the damping ratio) that directly influence the nonlinear dynamics of the nanostructure have been derived. Subsequently, by calculating their response with the varied nonlocal coefficient, it is unveiled that the nonlocal effect makes more obvious impacts at the starting range (from zero to a small value), while the impact of nonlocal effect becomes weaker when the nonlocal term reaches to a certain threshold value. Furthermore, to characterize the role played by nonlocal effect in exerting influence on nonlinear behaviors such as bifurcation and chaos (typical phenomena in nonlinear dynamics of nanoscale devices), we have calculated the Lyapunov exponents and bifurcation diagram with and without nonlocal effect, and results shows the nonlocal effect causes the most significant effect as the device is at resonance. This work advances the development of nanowire resonators that are working beyond linear regime.
ABSTRACT
A new electromechanical transistor based on an optical driven vibrational ring structure has been postulated. In the device, optical power excites the ring structure to vibrate, which acts as the shuttle transporting electrons from one electrode to the other forming the transistor. The electrical current of the transistor is adjusted by the optical power. Coupled opto-electro-mechanical simulation has been performed. It is shown from the dynamic analysis that the stable working range of the transistor is much wider than that of the optical wave inside the cavity, i.e., the optical resonance enters nonperiodic states while the mechanical vibration of the ring is still periodic.
