L-Glutamic acid (L-Glu) is a basic unit of proteins and also serves as an important neurotransmitter in the central nervous system. Its structural properties are critical for biological functions selective receptor recognition. Although this molecule has been extensively studied, low frequency vibrational behavior that closely related to conformational changes intermolecular interactions between L-Glu its receptors still unclear. In study, we acquired fingerprint spectrum by using air plasma...

The dynamic behavior of a monolithic dual-wavelength distributed feedback laser was fully investigated and mapped. combination different driving currents for master slave lasers can generate wide range operational modes, from single mode, period 1 to chaos. Both the optical microwave spectrum were recorded analyzed. detected mode signal continuously cover 15GHz 50GHz, limited by photodetector bandwidth. measured four-wave-mixing pattern indicates that 70GHz be generated this device. By...

Human activity recognition (HAR) has become increasingly essential due to its potential support a broad array of applications, e.g., elder care, and VR games. Recently, some pioneer WiFi-based HAR systems have been proposed privacy-friendly device-free characteristics. However, their crucial limitation lies in ignoring the inevitable impact co-channel interference (CCI), which degrades performance these significantly. To address this challenge, we propose PhaseAnti, novel system exploit CCI-...

We report a terahertz quantum-cascade vertical-external-cavity surface-emitting laser (QC-VECSEL) emitting around 1.9 THz with up to 10% continuous fractional frequency tuning of single mode. The device shows lasing operation in pulsed mode 102 K high-quality beam, the maximum output power 37 mW and slope efficiency 295 mW/A at 77 K. Challenges for up-scaling operating wavelength QC metasurface VECSELs are identified.

This article introduces a silicon-based source that can radiate power from the lower end of terahertz (THz) spectrum into far-infrared region.The radiator consists millimeter-wave (mm-wave) oscillator drives PIN diode multiplier.The p-i-n diodes exhibit reverse recovery when driven strongly, and switches large amount current in short interval.This process is highly non-linear generates harmonic-rich waveform, which utilized here for higher harmonic generation.An on-chip folded dipole antenna...

Abstract Radiofrequency (RF) injection locking and spectral broadening of a terahertz (THz) quantum‐cascade vertical‐external‐cavity surface‐emitting laser (QC‐VECSEL) is demonstrated. An intracryostat VECSEL focusing cavity design used to enable continuous‐wave lasing with length over 30 mm, which corresponds round‐trip frequency near 5 GHz. Strong RF current modulation injected the QC‐metasurface electrical bias pull lock frequency. The range at various powers recorded compared theory....

Driven by a wide range of essential applications, significant achievements have recently been made to explore WiFi-based Human Activity Recognition (HAR) techniques that utilize the information collected commercial off-the-shelf (COTS) WiFi infrastructures infer human activities without need for subject carry any devices. Although existing HAR systems achieve satisfactory performance in some instances, they are faced with severe challenge impacts ubiquitous Co-channel Interference (CCI) on...

Terahertz (THz) external-cavity lasers based on quantum-cascade (QC) metasurfaces are emerging as widely-tunable, single-mode sources with the potential to cover 1--6 THz range in discrete bands milliwatt-level output power. By operating an ultra-short cavity a length order of wavelength, QC vertical-external-cavity surface-emitting-laser (VECSEL) architecture enables continuous, broadband tuning while producing high quality beam patterns and scalable power output. The methods challenges for...

Ni-base superalloy FM-52M is mainly used in welded structures of key equipment nuclear power plants, such as pressure vessels and heat dissipation evaporators. It prone to form coarse columnar microstructures during welding has significant ductility dip cracking (DDC) susceptibility. This work attempted introduce micrometre-sized TiC particles into welds refine the microstructure alleviate sensitivity DDC. A Ni–TiC coating with good dispersion uniformity was first prepared on substrate by...

We report continuous wave (cw) operation of a terahertz quantum-cascade vertical-external-cavity surface-emitting laser with an external cavity length approximately 30 mm, benefited by intra-cryostat focusing cavity. Compared to previous plano–plano cavities, off-axis paraboloid mirror is introduced into the as element reduce diffraction loss and enable cw lasing using small-area metasurfaces long lengths. The device shows in mode up 111 K, output power 11.5 mW at 77 K (0.5% wall-plug...

To date, terahertz quantum-cascade vertical-external-cavity surface-emitting lasers (QC-VECSELs) have tended to oscillate in only one or two lasing modes at a time. This is due the fact that interaction between all of longitudinal external cavity and QC gain material mediated through single metasurface resonance, whose spatial overlap changes little with frequency; this suppresses spatial-hole-burning induced multi-mode operation. In Letter, VECSEL demonstrated using an output coupler based...

This paper presents a silicon-based source that can radiate power beyond 1 THz. A PIN diode frequency multiplier is driven by Colpitts oscillator designed at fundamental of 130 GHz. The exhibits sharp reverse recovery, which be exploited for strong harmonic generation in THz band. Wireless injection locking also demonstrated to lock the chip an external and reduce phase noise. design implemented GlobalFoundries 90 nm SiGe BiCMOS process has effective isotropic radiated (EIRP) 13 dBm 6%...

RF modulation of the injected current at cavity round trip frequency is a viable path towards multi-mode operation in THz metasurface quantum-cascade VECSEL. Under weak modulation, pulling and locking round-trip to signal observed; under strong broadening lasing spectrum with maximum observable bandwidth as large 300 GHz demonstrated. It shown that injection behavior sensitive length (varied between 35-50 mm), well presence optical feedback. Long-travel FTIR measurements enable resolution modes.

Harmonic and sub-harmonic RF injection locking is demonstrated in a terahertz (THz) quantum-cascade vertical-external-cavity surface-emitting laser (QC-VECSEL).By tuning the frequency around integer multiples submultiples of cavity round-trip frequency, different harmonic subharmonic orders can be excited same device.Modulation-dependent behavior device has been studied with recorded lasing spectral broadening bandwidths each case.In particular, results observation spectra over 200 GHz.A...

7N01 Al alloy is used extensively in high-speed train production. The mechanical properties of Al–Zn–Mg–Cu alloys are known to be closely related the characteristics their precipitates, which greatly affected by heat-treatment temperature. Herein, differential scanning calorimetry (DSC) and transmission electron microscopy (TEM) were investigate precipitation kinetics structure η precipitates alloy. solution temperature range activation energy determined using DSC analysis, chemical...

We report advances in the development of THz quantum-cascade metasurface VECSELs intended for use as local oscillators terahertz heterodyne receiver instruments astrophysical investigation interstellar medium. First, by using a patch-based amplifying we obtain QC-VECSEL lasing with milliwatt output power at 4.6 reduced consumption less than 1 W. Second, phase locking 3.4 to microwave reference Schottky diode mixer. Finally, efforts and challenges scale down frequency 1.9 THz.

RF injection locking of a terahertz Quantum-Cascade Vertical-External-Cavity Surface-Emitting Laser (QC-VECSEL) is demonstrated. The intra-cryostat focusing VECSEL cavity design allows continuous wave lasing in an external length over 30 mm with round-trip frequency near 5 GHz. Strong current modulation applied to the QC-metasurface frequency; this broadens THz emission spectrum from single mode multi-mode operation around 200 GHz spectral width. Round-trip pulling and injected signal observed.

A terahertz quantum-cascade VECSEL is demonstrated to exhibit multi-mode operation, despite the fact that spatial-hole burning nominally suppressed within amplifying metasurface. specially designed output coupler mirror used such large numbers of modes have nearly identical lasing thresholds. Up nine with a FSR approximately 21 GHz are – significant increase from previous QC-VECSELs in which only 2 or 3 been observed lase at once. This work an intermediate step towards eventually...

An off-axis paraboloid mirror is introduced into the intra-cryostat quantum-cascade VECSEL cavity as a focusing element to reduce diffraction loss. Continuous-wave lasing at 3.4 THz obtained with length ~27 mm.