Physics

O conhecimento do espalhamento e do tempo de evaporacao de gotas de pulverizacao e fundamental para entender a interacao entre a calda de fungicida e a superficie alvo para que aconteca adequada distribuicao do fungicida e protecao do alvo. O objetivo desta pesquisa foi determinar a area de molhamento e o tempo de evaporacao de gotas contendo o fungicida Cabrio® Top sem e com o adjuvante Nimbus® depositadas em superficies foliares das culturas de tomate, pimentao, pepino e superficie artificial (lâmina de vidro). Foi utilizado um sistema de analises por imagens composto de um gerador de gotas, um estereoscopio com câmera para captura de imagens e uma câmara climatica de controle de temperatura e umidade relativa do ar. Gotas de 600 µm de diâmetro contendo as caldas de pulverizacao foram depositadas nas superficies foliares e lâmina de vidro e as imagens sequenciais foram usadas para quantificar a area de molhamento e o tempo de evaporacao. A calda de pulverizacao e a superficie alvo...

This paper presents a theoretical study and design of two techniques used to reduce start-up time (TS) and energy (ES) of Pierce crystal oscillator (XO). An analytical study of precise injection on a crystal resonator is introduced, and based on this study, a relaxation oscillator with a dithered frequency is designed. Next, a study of negative resistance of XO's active circuitry and a method to boost its value beyond the limit set by crystal static capacitor are presented. A gyrator-C active inductor with high linearity is developed to accelerate the start-up process by boosting the negative resistance. A prototype integrating these techniques is fabricated in a 180 nm CMOS process, and shows a significant improvement compared to prior art. Specifically, TS and ES are reduced by 102.7× and 2.9×, compared to the XO start-up with no assisting circuitry, to 18 µs and 114.5 nJ for a 48 MHz XO across -40-90 • C temperature range. The measured steady-state power and phase noise of the XO are 180 µW and -135 dBc/Hz at 1 kHz offset.

The analysis, design, and implementation of a 50-Gb/s transimpedance amplifier (TIA) in a 0.13-μm SiGe BiCMOS process are presented. The proposed TIA, designed for use in a single-channel optical communication network, is comprised of three stages including: 1) a shunt-peaked, shuntseries feedback stage incorporating a transformer-based positive feedback; 2) an RC-degenerated common-emitter stage; and 3) an inductively degenerated emitter follower. The TIA chip integrates an on-chip 100-fF input capacitor to emulate the photo-detector junction capacitor, and achieves a measured transimpedance gain of 41 dB and an input-referred currentnoise spectral density of 39.8 pA/ √ H z over a 50-GHz bandwidth. The TIA achieves an open eye at 50 Gbps with random jitter of 2.3-ps rms (including the jitter contribution of the test fixture). The prototype chip occupies 0.58 mm 2 (including pads) of die area and dissipates 24 mW of dc power from a 2-V supply voltage (i.e., less than 0.5 pJ/bit).

This paper presents the design and implementation of a millimeter-wave (mm-wave) fundamental frequency circularly polarized radiator which employs a multi-port cavity as the core of a high-Q resonator, a power combiner, and an antenna. A general theory of multi-port oscillators -and in particular, the widely used circularly symmetric oscillator topologies -is presented, which quantitatively investigates and predicts all possible oscillation states, their associated modes of operation, and the oscillation stability. The outcomes of this theory are utilized to design a power-optimized 8-port rotationally symmetric radiator, excited at the oscillation state with 45 phase-difference between the adjacent ports, which, in turn, enables a high-efficiency circularly polarized radiation. Fabricated in 0.13µm BiCMOS process, this cavity-backed circularly polarized radiator operates at frequency of 114GHz and achieves 14.2dBm EIRP, 5.2% DCto-EIRP conversion efficiency, 8.2dBm radiated power, 1.3% DCto-radiation efficiency, and -99.3dBc/Hz phase noise at 1MHz offset, without using silicon lens.

A novel high-speed wireless transmitter (TX) architecture is presented that directly transforms incoming data bits into high-order 4 M -quadrature amplitude modulation (QAM) constellation by adding multiple quadrature phase shift keying (QPSK) signals with appropriate amplitude ratios. The costly high-speed digital-to-analog converters (DACs) in conventional TXs are thus completely avoided, resulting in a highly integrated solution amenable to ultra-high speeds and operating frequencies. Design tradeoffs are analyzed in detail. Based on this article, a TX prototype at 115-GHz carrier frequency implementing the 16QAM direct-modulation scheme is fabricated in a 180-nm SiGe BiCMOS process ( f MAX = 270 GHz). Wireless testing at a 20-cm distance with 25-dBi horn antennas on both transmitting and receiving side measures 20-Gb/s data rate with an error vector magnitude (EVM) of -15.8 dB and modulated output power of +1 dBm. The TX consumes 520 mW of power and occupies 3.17 mm 2 of active area.

A wideband, low-loss balun-based differential power splitter is studied. The use of lumped double-tuned baluns as key building blocks within a splitter leads to a wideband operation, while avoiding signal crossovers and the detrimental effects associated with them. Moreover, the lack of multiple λ/4 transmission-line (T-line) sections results in an area-efficient and low-loss structure. A demonstration of this design approach comprising a differential 1-to-4 splitter was EM-simulated at 120 GHz in a 65nm CMOS process. Full-wave EM-simulations, verifying the performance of this splitter, show a minimum inband insertion loss of 8.3 dB and a port-to-port isolation of 10 dB (or better) across a 3-dB bandwidth of 40 GHz.

A CMOS 170-GHz fundamental-frequency transmitter (TX) realizing the 8PSK modulation scheme directly in the RF domain is presented. The use of direct RF modulation obviates the need for high-resolution high-speed mixed-signal blocks. The proposed architecture extends the conventional quadrature modulation by performing additional phase modulation on I and Q components of the LO signal, which helps increase modulation order. The TX employs highspeed switchable phase shifters to achieve LO phase modulation and fundamental-frequency over-neutralized power amplifiers to drive an integrated two-element tapered dipole antenna array. Fabricated in a 65-nm CMOS process ( f T / f max = 230/260 GHz), the RF-8PSK TX prototype occupies 3.2 × 2.8 mm 2 of die area. The free-space wireless measurement of the TX over a 10-cm link range yields 15 Gb/s data rate at an error vector magnitude (EVM) of -14.8 dB. The TX achieves an EIRP of 4 dBm while consuming 560-mW power.

This paper presents a 53-61GHz low-power chargepump integer-N type-II PLL, employing a class-D V-band VCO. Transistors in the VCO enter deep triode region to achieve low DC power and phase noise. Pros and cons of the triode region are studied in this paper. We have explained how this region has been accurately exploited to reduce the phase-noise. This is unlike the general notion that the triode region degrades phase-noise performance in oscillators. The PLL is fabricated in a standard 65nm CMOS process. The VCO consumes the minimum power of 10.6mW from 0.8V supply. The PLL achieves a wide tuning range of 13% from 53.35-to 60.83-GHz and a phase noise of -88 dBc/Hz at 1MHz offset, while consuming a minimum DC power of 48mW. This PLL can be used as part of the LO generation network for millimeter-wave phased-array transceivers.

An inductorless MedRadio (413∼419 MHz) OOK transceiver for an implantable brain-machine interface (BMI) in 180 nm CMOS is presented. An event-driven supply modulation (EDSM) technique is introduced in the receiver to lower the power consumption to 42/92 μW at 1/10 kbps, achieving -79/-74 dBm sensitivity (at 0.1% BER). The transmitter employs a current-starved ring oscillator with an automatic frequency calibration loop, achieving 14% efficiency for random OOK data at -4 dBm output power. Wireless connection, benchtop, multi-user coexistence, and in-vitro phantom test results are demonstrated.

MedRadio 413-419 MHz inductorless transceiver (TRX) for an implantable brain-machine interface (BMI) in a 180 nm CMOS process is presented. Occupying 5.29 mm 2 of die area (including pad ring), this on-off-keying (OOK) TRX employs a non-coherent direct-detection receiver (RX), which exhibits a measured in-band noise figure (NF) of 4.9 dB and S11 of -13.5 dB. An event-driven supply modulation (EDSM) technique is introduced to dramatically lower the RX power consumption. Incorporating an adaptive feedback loop, this RX consumes 42/92 µW power from 1.8 V supply at 1/10 kbps data-rates, achieving -79/-74 dBm sensitivities for 0.1% bit-error-rate (BER). The TX employs a current-starved ring oscillator with an automatic frequency calibration loop, covering 9% supply-voltage variation and 15-78 • C temperature range which guarantees operation within the emission mask. The direct-modulation TX achieves 14% efficiency for a random OOK data sequence at -4 dBm output power. Wireless testing over a 350 cm distance accounting for bio-signal data transfer, multi-user coexistence, and in-vitro phantom measurement results are demonstrated.

Two brain signal acquisition (BSA) front-ends incorporating two CMOS ultra-low power low noise amplifier arrays and serializers operating in MOSFET weak inversion region are presented. To boost the amplifier's gain for a given current budget, cross-coupled-pair active load topology is used in the first stages of these two amplifiers. These two BSA frontends are fabricated in 130 nm and 180nm CMOS processes, occupying 5.45 mm 2 and 0.352 mm 2 of die areas, respectively (excluding pad rings). The CMOS 130 nm amplifier array is comprised of 64 elements, where each amplifier element consumes 0.216 μW from 0.4 V supply, has input-referred voltage noise (IRNoise) of 2.19 μV RM S corresponding to a power efficiency factor (PEF) of 11.7 and occupies 0.044 mm 2 of die area. The CMOS 180 nm amplifier array employs 4 elements, where each element consumes 0.69 μW from 0.6 V supply with IRNoise of 2.3 μVRMS (corresponding to a PEF of 19.3) and 0.051 mm 2 of die area. Non-invasive electroencephalographic (EEG) and invasive electrocorticographic (ECoG) signals were recorded real-time directly on able-bodied human subjects, showing feasibility of using these analog front-ends (AFEs) for future fully implantable brain signal acquisition and brain computer interface systems. Index Terms -CMOS, Electrocorticography (ECoG), Electroencephalogram (EEG), ultra-low power (ULP), noise efficiency factor (NEF), power efficiency factor (PEF), operational transconductance amplifier (OTA), instrumentation amplifier (InAmp), analog front-end (AFE), weak inversion (WI) region.

This paper presents the analysis, design and implementation of a millimeter-wave W-band power detector. Fabricated in a 0.18-ȝm SiGe BiCMOS technology, the detector circuit exhibits a responsivity of 91 kV/W, a noise equivalent power of 0.5 pW/Hz 1/2 , and a noise figure of 29 dB. The power dissipation of the detector is 75 ȝW. Reasonable agreement between simulations and measurements is obtained. To the authors' best knowledge, the detector in this work achieves the highest responsivity reported to date for any solid-state W-band detector.

The design of a CMOS 22-29-GHz pulse-radar receiver (RX) front-end for ultra-wideband automotive radar sensors is presented. The chip includes a low-noise amplifier, in-phase/quadrature mixers, a quadrature voltage-controlled oscillator (QVCO), pulse formers, and baseband variable-gain amplifiers. Fabricated in a 0.18-m CMOS process, the RX front-end chip occupies a die area of 3 mm 2 . On-wafer measurements show a conversion gain of 35-38.1 dB, a noise figure of 5.5-7.4 dB, and an input return loss less than 14.5 dB in the 22-29-GHz automotive radar band. The phase noise of the constituent QVCO is 107 dBc/Hz at 1-MHz offset from a center frequency of 26.5 GHz. The total dc power dissipation of the RX including output buffers is 131 mW.

This paper investigates the impact of clock jitter induced by substrate noise on the performance of the oversampling 16 modulators. First, a new stochastic model for substrate noise is proposed. This model is then utilized to study the clock jitter in clock generators incorporating phase-locked loops (PLLs). Next, the effect of the clock jitter on the performance of the 16 modulator is studied. It will be shown that substrate noise degrades the signal-to-noise ratio of the 16 modulator while the noise shaping does not have any effect on clock jitter induced by substrate noise. To verify the analysis experimentally, a circuit consisting of a second-order 16 modulator, a charge-pump PLL, and forty multistage digital tapered inverters driving 1-pF capacitors is designed in a 0.25-m standard CMOS process. Several experiments on the designed circuit demonstrate the high accuracy of the proposed analytical models.

This paper presents a W-band receiver chipset for passive millimeter-wave imaging in a 65 nm standard CMOS technology. The system comprises a direct-conversion receiver front-end with injection-locked tripler and a companion analog back-end for Dicke radiometer. The receiver design addresses the high 1/f noise issue in the advanced CMOS technology. An LO generation scheme using a frequency tripler is proposed to lower the PLL frequency, making it suitable for use in multi-pixel systems. In addition, the noise performance of the receiver is further improved by optimum biasing of transistors of the detector in moderate inversion region to achieve the highest responsivity and lowest NEP. The front-end chipset exhibits a measured peak gain of 35 dB, 3 dB BW of 12 GHz, NF of 8.9 dB, while consuming 94 mW. The baseband chipset has a measured peak responsivity ( ) of 6 KV/W and a noise equivalent power (NEP) of 8.54 pW Hz 1 2 . The two chipsets integrated on-board achieve a total responsivity of 16 MV/W and a calculated Dicke NETD of 1K with a 30 ms integration time.

This paper presents a W-band 2 2 focal-plane array (FPA) for passive millimeter-wave imaging in a standard 0.18 m SiGe BiCMOS process ( GHz). The FPA incorporates four Dicke-type receivers representing four imaging pixels. Each receiver employs the direct-conversion architecture consisting of an on-chip slot folded dipole antenna, an SPDT switch, a low noise amplifier, a single-balanced mixer, an injection-locked frequency tripler (ILFT), an IF variable gain amplifier, a power detector, an active bandpass filter and a synchronous demodulator. The LO signal is generated by a shared Ka-band PLL and distributed symmetrically to four local ILFTs. The measured LO phase noise is at 1 MHz offset from the 96 GHz carrier. This imaging receiver (without antenna) achieves a measured average responsivity and noise equivalent power of 285 MV/W and 8.1 , respectively, across the 86-106 GHz bandwidth, which results a calculated NETD of 0.48 K with a 30 ms integration time. The system NETD increases to 3 K with on-chip antenna due to its low efficiency at W-band. MMW images have been generated in transmission mode. This work demonstrates the highest integration level of any silicon-based systems in the 94 GHz imaging band.

Design and implementation of a -band on-chip bowtie-shaped slot antenna fabricated in 180-nm BiCMOS process is presented, and its performance and limitations are discussed. This antenna has a measured impedance bandwidth ( dB) across the -band frequency range and a very wide gain bandwidth, making it a candidate for wideband applications. The measured gain for this antenna is 0-1 dBi at 94 GHz. This letter also analyzes the influence of the RF probe to the on-chip antenna performance.

Background: Clinical treatments with typical antipsychotic drugs (APDs) are accompanied by extrapyramidal motor sideeffects (EPS) such as hypokinesia and catalepsy. As little is known about electrophysiological substrates of such motor disturbances, we investigated the effects of a typical APD, a-flupentixol, on the motor behavior and the neuronal activity of the whole basal ganglia nuclei in the rat. The motor behavior was examined by the open field actimeter and the neuronal activity of basal ganglia nuclei was investigated using extracellular single unit recordings on urethane anesthetized rats. We show that aflupentixol induced EPS paralleled by a decrease in the firing rate and a disorganization of the firing pattern in both substantia nigra pars reticulata (SNr) and subthalamic nucleus (STN). Furthermore, a-flupentixol induced an increase in the firing rate of globus pallidus (GP) neurons. In the striatum, we recorded two populations of medium spiny neurons (MSNs) after their antidromic identification. At basal level, both striato-pallidal and striato-nigral MSNs were found to be unaffected by a-flupentixol. However, during electrical cortico-striatal activation only striato-pallidal, but not striato-nigral, MSNs were found to be inhibited by a-flupentixol. Together, our results suggest that the changes in STN and SNr neuronal activity are a consequence of increased neuronal activity of globus pallidus (GP). Indeed, after selective GP lesion, a-flupentixol failed to induce EPS and to alter STN neuronal activity. Our study reports strong evidence to show that hypokinesia and catalepsy induced by a-flupentixol are triggered by dramatic changes occurring in basal ganglia network. We provide new insight into the key role of GP in the pathophysiology of APD-induced EPS suggesting that the GP can be considered as a potential target for the treatment of EPS.

A W-band direct-detection-based receiver front-end for millimeter-wave passive imaging in a 0.18-m BiCMOS process is presented. The proposed system is comprised of a direct-detection front-end architecture employing a balanced LNA with an embedded Dicke switch, power detector, and baseband circuitry. The use of a balanced LNA with an embedded Dicke switch minimizes front-end noise figure, resulting in a great imaging resolution. The receiver chip achieves a measured responsivity of 20-43 MV/W with a front-end 3-dB bandwidth of 26 GHz, while consuming 200 mW. The calculated NETD of the SiGe receiver chip is 0.4 K with a 30 ms integration time. This work demonstrates the possibility of silicon-based system-on-chip solutions as lower cost alternatives to compound semiconductor multi-chip imaging modules.

We propose to use the blind deconvolution and its modification to extract the point spread function (PSF) of layered metamaterials from a SNOM measurement. The measurement results are processed using the blind deconvolution algorithm to reconstruct the real-valued non-coherent PSF, or using the modified blind deconvolution introduced in this paper to reconstruct the complex-valued coherent PSF. The two algorithms are tested in simulations with a layered metamaterial deposited on a thin metallic mask with test apertures. We show that the modified algorithm is capable of recovering the approximate shape of complex PSF with a sub-wavelength full width at half maximum from a measurement in which the apertures are larger than the wavelength.

Imaging with a layered superlens is a spatial filtering operation characterized by the point spread function (PSF). We show that in the same optical system the image of a narrow sub-wavelength Gaussian incident field may be surprisingly dissimilar to the PSF, and the width of PSF is not a straightforward measure of resolution. FWHM or std. dev. of PSF give ambiguous information about the actual resolution, and imaging of objects smaller than the FWHM of PSF is possible. A multiscale analysis of imaging gives good insight into the peculiar scale-dependent properties of sub-wavelength imaging.

We compare the properties of subwavelength imaging in the visible wavelength range for metal-dielectric multilayers operating in the canalization and the resonant tunnelling regimes. The analysis is based on the transfer matrix method and time domain simulations. We show that Point Spread Functions for the first two resonances in the canalization regime are approximately Gaussian in shape. Material losses suppress transmission for higher resonances, regularise the PSF but do not compromise the resolution. In the resonant tunnelling regime, the MTF may dramatically vary in their phase dependence. Resulting PSF may have a subwavelength thickness as well as may be broad with multiple maxima and a rapid phase modulation. We show that the width of PSF may be reduced by further propagation in free space, and we provide arguments to explain this surprising observation.

Dana desa harus dimanfaatkan dan digunakan untuk kepentingan desa dan pelaksanaannya diawasi bersama serta dilengkapi dengan laporan-laporan secara tertulis agar dapat dipertanggungjawabkan. Masih sangat sedikit aparatur pemerintah desa dalam memberikan laporan pengelolaan dana desa, sehingga memunculkan pertanyaan mengenai bagaimana kinerja pengelolaan dana desa. Penelitian bermaksud untuk menganalisis persepsi dari aparatur pemerintah desa berdasarkan prinsip Good Governance dengan dimensi transparansi, akuntabilitas dan partisipasi dan kapasitas aparatur desa terhadap kinerja pengeloaan dana desa dengan sistem pengendalian internal sebagai variabel moderating. Penelitian dilakukan di  Kecamatan Karangawen Kabupaten Demak pada pihak yang terlibat dalam pengelolaan dana desa yaitu kepala desa, sekretaris desa, bendahara, pelaksana kegiatan pembangunan, pelaksana kegiatan pemerintahan, ketua tim pengelola kegiatan dan tim penggerak kesejahterahteraan keluarga, pada 12 desa dengan ju...

Background and Objective: Cleanroom is a tightly enclosed environment where airborne particles are under control and is a necessary environment in pharmaceutical industries to produce quality products. Hence, we sought to assess and simulate particle dispersion and track particles in a cleanroom by computational fluid dynamics (CFD) method in a pharmaceutical industry. Materials and Methods: This experimental study was conducted in 2015 in a pharmaceutical industry. We evaluated particle concentration and number in the cleanroom according to ISO 14644 -3 standard. In addition, air flow pattern and particle dispersion in the cleanroom with cleanliness class of C was simulated based on CFD. The results showed that the path of particle movement and distribution and dispersion of particles in the cleanroom are completely dependent on flow shape and the pattern of air flow in the cleanroom. Furthermore, the simulation results showed that wall return had efficiency of higher than 70% for particle sizes of 0.5 and 5 microns. Equipment and tools existing in the cleanroom affect the air flow pattern, and in turn, particle removal efficiency. Moreover, particle dispersion simulation in the cleanroom illustrated that air flow pattern exerts the highest impact on particle removal in cleanrooms.

In this paper, we present a numerical approach to solve the GNLSE and analyze soliton interaction phenomena using COMSOL environment. By leveraging the capabilities of COMSOL's PDE module, we can accurately capture the dynamics of solitons and investigate their interactions. We analyze the impact of different parameters such as soliton power, initial separation distance, and dispersion characteristics on the soliton dynamics. Furthermore, we examine the role of higher-order dispersion terms in shaping the soliton interactions. Our findings demonstrate the effectiveness of the proposed numerical approach in accurately simulating and analyzing soliton interaction phenomena. The COMSOL-based methodology provides a flexible and efficient framework for studying complex nonlinear optical systems, enabling researchers to gain insights into the behavior of solitons in different media and design optimized communication systems. This paper contributes to the understanding of soliton dynamics and provides a practical tool for investigating the behavior of solitons in nonlinear dispersive media. The presented numerical approach using COMSOL opens avenues for further research in nonlinear optics and fiber optic communication systems.

Penelitian ini bertujuan untuk menganalisis pengaruh keberadaan industri dan PLTU terhadap lingkungan di Provinsi Banten. Dengan analisis menggunakan metode DPSIR, diketahui impact dari emisi yang dihasilkan dari pembakaran batubara sebagai bahan baku PLTU serta dari industri adalah gangguan sistem pernafasan sebagai efek paling ringan, serta risiko kematian dini sebagai efek paling berat. Response yang telah dilakukan Pemerintah Provinsi Banten lebih banyak dari sisi hilir, seperti evaluasi, pembinaan, pengawasan serta penurunan beban pencemaran. Tujuan dari penelitian ini adalah untuk mengidentifikasi upaya dari sisi hulu, yaitu perencanaan dan kebijakan yang tidak hanya berorientasi pada pembangunan ekonomi dan pencapaian target nasional saja, tetapi sektor lingkungan dan sosial juga dapat diinternalisasi. Salah satu upaya yang dapat dipertimbangkan adalah perhitungan PDRB hijau. Hasil perhitungan PDRB hijau di Provinsi Banten tahun 2018 sebesar Rp 396,6 T atau 91,4% dari nilai PDRB konvensional. Dengan hasil perhitungan PDRB hijau diharapkan dapat memberikan pemahaman pentingnya internalisasi lingkungan dalam pembangunan.

Todays, there are various of systems that requires high-level security methods. Due to the sophisticated methods of breaking the traditional security methods. One of the most advanced methods nowadays is handprint validation. Which is based on the features of the palm in hands. These feature could include the lines, valleys, hand texture, and other features. In this work, a survey of the latest works that are used for palm print detection and recognition

A theoretical concept of resonant Rayleigh scattering (RRS) of exciton-polaritons in multiple quantum wells (QWs) is presented. The optical coupling between excitons in different QWs can strongly affect the RRS dynamics, giving rise to characteristic temporal oscillations on a picosecond scale. Bragg and anti-Bragg arranged QW structures with the same excitonic parameters are predicted to have drastically different RRS spectra. Experimental data on the RRS from multiple QWs show the predicted strong temporal oscillations at small scattering angles, which are well explained by the presented theory.

Scientific curiosity to uncover original optical properties and functionalities of atomically thin semiconductors, stemming from unusual Coulomb interactions in the two-dimensional geometry and multi-valley band structure, drives the research on monolayers of transition metal dichalcogenides (TMDs). While recent works ascertained the exotic energetic schemes of exciton complexes in TMDs, we here employ four-wave mixing microscopy to indicate that their subpicosecond dynamics is determined by the surrounding disorder. Focusing on a monolayer WS2, we observe that exciton coherence is lost primarily due to interaction with phonons and relaxation processes towards optically dark excitonic states. Notably, when temperature is low and disorder weak excitons large coherence volume results in huge oscillator strength, allowing to reach the regime of radiatively limited dephasing and we observe long valley coherence. We thus elucidate the crucial role of exciton environment in the TMDs on its dynamics and show that revealed mechanisms are ubiquitous within that family.

We report on the exciton and trion density dynamics in a single layer of MoSe2, resonantly excited and probed using three-pulse four-wave mixing (FWM), at temperatures from 300 K to 77 K . A multi-exponential third-order response function for amplitude and phase of the heterodyne-detected FWM signal including four decay processes is used to model the data. We provide a consistent interpretation within the intrinsic band structure, not requiring the inclusion of extrinsic effects. We find an exciton radiative lifetime in the sub-picosecond range consistent to what has been recently reported 1 . After the dominating radiative decay, the remaining exciton density, which has been scattered from the initially excited bright radiative state into dark states of different nature by exciton-phonon scattering or disorder scattering, shows a slower dynamics, covering 10ps to 10ns timescales. This includes direct bright transitions with larger in-plane momentum, as well as indirect dark transitions to indirect dark states. We find that exciton-exciton annihilation is not relevant in the observed dynamics, in variance from previous finding under non-resonant excitation. The trion density at 77 K reveals a decay of the order of 1 ps, similar to what is observed for the exciton. After few tens of picoseconds, the trion dynamics resembles the one of the exciton, indicating that trion ionization occurs on this timescale.

Spontaneous emission from excitonic transitions in InAs/GaAs quantum dots embedded in photonic crystal waveguides at 5 K into non-guided and guided modes is determined by direct hyperspectral imaging. This enables measurement of the absolute coupling efficiency into the guided modes, the beta factor, directly, without assumptions on decay rates used previously. Notably, we found beta factors above 90% over a wide spectral range of 40 meV in the fast light regime, reaching a maximum of (99 ± 1)%. We measure the directional emission of the circularly polarized transitions in a magnetic field into counter-propagating guided modes, to deduce the mode circularity at the quantum dot sites. We find that points of high directionality, up to 97%, correlate with a reduced beta factor consistent with their positions away from the mode field antinode. By comparison with calibrated finite-difference time-domain simulations, we use the emission energy, mode circularity and beta factor to estimate the quantum dot position inside the photonic crystal waveguide unit cell. I.

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The dephasing time of the lowest bright exciton in CdSe=ZnS wurtzite quantum dots is measured from 5 to 170 K and compared with density dynamics within the exciton fine structure using a sensitive threebeam four-wave-mixing technique unaffected by spectral diffusion. Pure dephasing via acoustic phonons dominates the initial dynamics, followed by an exponential zero-phonon line dephasing of 109 ps at 5 K, much faster than the $10 ns exciton radiative lifetime. The zero-phonon line dephasing is explained by phonon-assisted spin flip from the lowest bright state to dark-exciton states. This is confirmed by the temperature dependence of the exciton lifetime and by direct measurements of the bright-dark-exciton relaxation. Our results give an unambiguous evidence of the physical origin of the exciton dephasing in these nanocrystals.

We develop an exact analytical approach to the optical response of a quantum dot-microcavity system for arbitrary excitation strengths. The response is determined in terms of the complex amplitudes of transitions between the rungs of the Jaynes-Cummings ladder, explicitly isolating nonlinearities of different orders. Increasing the pulse area of the excitation field, we demonstrate the formation of a quantum Mollow quadruplet (QMQ), quantizing the semi-classical Mollow triplet into a coherent superposition of a large number of transitions between rungs of the ladder, with inner and outer doublets of the QMQ formed by densely lying inner and outer quantum transitions between the split rungs. Remarkably, a closed-form analytic approximation for the QMQ of any order of nonlinearity is found in the high-field low-damping limit.

Binding of the heavy-hole excitons and biexcitons in GaAs/Al 0.3 Ga0.7As superlattices is studied using linear and nonlinear optical techniques. High biexciton binding energies characteristic of quasi two-dimensional biexcitons are observed in superlattices with considerable miniband dispersion.

Using a high-quality GaAs planar microcavity, we optically generate polariton pairs, and verify their correlations by means of time-resolved single-photon detection. We find that correlations between the different modes are consistently lower than identical mode correlations, which is attributed to the presence of uncorrelated background. We discuss a model to quantify the effects of such a background on the observed correlations. Using spectral and temporal filtering, the background can be suppressed and a change in photon statistics towards non-classical correlations is observed. These results improve our understanding of the statistics of polariton-polariton scattering and background mechanisms, and pave the way to the generation of entangled polariton pairs.

Small Industry is an industrial company whose workforce consists of 5-19 people. While the Micro Industry is an industrial company whose workforce consists of 1-4 people. The purpose of this study is to estimate the Production Index of Micro and Small Industries according to KBLI for years to come. KBLI is a reference classification used to classify Indonesian economic activities/activities into several business fields/business fields that are distinguished based on the type of economic activity that produces products/outputs in the form of goods and services. In this study, the estimation method used is the Bayesian Regulation Algorithm. This algorithm is one of the Artificial Neural Networks algorithms that can solve many estimation problems by building a trained model and showing good performance. The data to be estimated in this study are data of Micro and Small Industry Production Index according to KBLI processed from the Central Board Statistics of Indonesia. This study uses ...

Strongly localized vorticity is a key ingredient of a broad variety of fluid phenomena, and its quantized version is considered to be the hallmark of superfluidity. Flows that correspond to vortices of a large topological charge, termed "giant vortices", are notoriously difficult to realise and even when externally imprinted, they are unstable, breaking into many vortices of a single charge. In spite of many theoretical proposals on the formation and stabilisation of giant vortices in ultra cold atomic Bose-Einstein condensates and other superfluid systems, their experimental realisation remains illusive. Polariton condensates stand out from other superfluid systems due to their particularly strong interparticle interactions combined with their non-equilibrium nature, and as such provide an alternative test-bed for the study of non-trivial vortices. Here, we show that by injecting an odd number of polariton condensates at the vertices of a regular polygon and imposing frus...

We have studied both theoretically and experimentally the luminescence spectra and kinetics of crystalline, disordered solid solutions after pulsed excitation. First, we present the model calculations of the steady-state luminescence band shape caused by recombination of excitons localized in the wells of random potential induced by disorder. Classification of optically active tail states of the main exciton band into two groups is proposed. The majority of the states responsible for the optical absorption corresponds to the group of extended states belonging to the percolation cluster, whereas only a relatively small group of ''radiative'' states forms the steady-state luminescence band. The continuum percolation theory is applied to distinguish the ''radiative'' localized states, which are isolated in space and have no ways for nonradiative transitions along the tail states. It is found that the analysis of the exciton-phonon interaction gives the information about the character of the localization of excitons. We have shown that the model used describes quite well the experimental cw spectra of CdS (1Ϫc) Se c and ZnSe (1Ϫc) Te c solid solutions. Further, the experimental results are presented for the temporal evolution of the luminescence band. It is shown that the changes of band shape with time come from the interplay of population dynamics of extended states and spatially isolated ''radiative'' states. Finally, the measurements of the decay of the spectrally integrated luminescence intensity at long delay times are presented. It is shown that the observed temporal behavior can be described in terms of relaxation of separated pairs followed by subsequent exciton formation and radiative recombination. Electron tunneling processes are supposed to be responsible for the luminescence in the long-time limit at excitation below the exciton mobility edge. At excitation by photons with higher energies the diffusion of electrons can account for the observed behavior of the luminescence. ͓S0163-1829͑99͒11419-X͔

We present an experiment that probes polariton quantum correlations by exploiting quantum complementarity. Specifically, we find that polaritons in two distinct idler modes interfere if and only if they share the same signal mode so that ''which-way'' information cannot be gathered. The experimental results prove the existence of polariton pair correlations that store the which-way information. This interpretation is confirmed by a theoretical analysis of the measured interference visibility in terms of quantum Langevin equations.