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A distributed fiber-optic acoustic sensor based on digital linear frequency modulated (LFM) pulse and coherent detection is proposed and its proof-of-concept experiment is demonstrated. High-performance measurement has been achieved for the intrapulse acoustic event, which is much shorter than the pulse spatial length. The actual acoustic sensing is achieved using the polystyrene membrane adhered to an only 9 cm long fiber at frequency of 1.5 kHz and 3 kHz. Compared with the direct detection configuration, the time domain envelope correlation coefficient of the coherent detection is twice that of the direct detection, and the standard deviation is less than one third. [ABSTRACT FROM AUTHOR]

A hybrid demodulation method based on coherent detection and pulse pair for distributed acoustic sensing is proposed. The Rayleigh backscattering light of pulse pair is coherent amplified by local reference light. A 3 × 3 fiber coupler is utilized to produce stable 2π/3 phase shift for phase extraction. The digital mixing of the beat signals of two pulses suppress the noise caused by phase drift and vibration on the local reference fiber. Several simulated acoustic waveforms are detected and retrieved. Experimental results show that the system has good linear response. And the equivalent strain of noise is as low as 0.4nε. [ABSTRACT FROM AUTHOR]

We investigated the dependence of MoTe2 thickness on it is electrical properties by fabricating several transistors with channel thickness between ∼6 layers and ∼46 layers. The transistor with ∼10-layer channel has the highest hole current, whereas the electron current shows monotonically increase with channel thickness. The measurements of Ids–Vds and temperature dependence show ohmic contact of p-type conduction and Schottky contact of n-type conduction. Thus, the highest hole current is observed in ∼10-layer MoTe2 due to the highest mobility. However, the bandgap of MoTe2 decreases with it is thickness, leading to the reduce of Schottky barrier and the increase of electrons current. [ABSTRACT FROM AUTHOR]

In this letter, a more intelligent three dimension transistor than a mere switching device is developed. The phosphorus doped silicon nanowire channel, SiO2 dielectric and three separated gates are applied for demonstrations with a gate length of 7 nm. The transistor is called “LIU MOSFET” due to its less interconnected unit characteristic. Logic “AND” and “OR” are achieved when the control gate is set to −3 V and 3 V, respectively. The logic function can be altered by external signals without any changes in the hardware. The demonstrated device is significant to the development of future integrated circuits. [ABSTRACT FROM AUTHOR]

We present a steep slope hybrid thin film transistor (TFT) that integrates an Ag/HfO2 based threshold switching (TS) with a ferroelectric HfZrO gated InGaZnO TFT. The hybrid TFT shows a minimum subthreshold swing of 16 mV decade. The negative differential resistance effect (NDR) was observed during the switching process of the TS. And the InGaZnO TFT shows a negative drain-induced barrier lowering (DIBL) effect. Furthermore, a Verilog-A model is developed to simulate the hybrid TFT. All of these suggests the as-fabricated hybrid TFT is suitable for low power TFT based applications. [ABSTRACT FROM AUTHOR]