Passively Q-Switched and Mode-Locked Er3+-Doped Ring Fiber Laser with Pulse Width of Hundreds of Picoseconds

Greatly improving the energy of a single mode-locked pulse while ensuring the acquisition of the width of short pulses will contribute to the application of mode-locked pulse in basic research, such as precision machining. This report has investigated a Q-switched and mode-locked (QML) erbium doped ring fiber laser based on the nonlinear polarization rotation (NPR) technology and a mechanical Q-switched device. Without the working of the mechanical Q-switched device, the fiber laser exported the continuous-wave mode-locked (CWML) pulse, with a width of 212.5 ps, and a repetition frequency of 81.97 MHz. For the CWML operation, the maximum output average power is 25.7 mW, and the energy is only 0.31 nJ. For the QML operation, 18.03 mW average power is achieved at the Q-switching frequency of 100 Hz. The energy of the QML pulse is increased by over 1100 times to 360.6 nJ. The width of the QML pulse is 203.1 ps measured by an autocorrelation curve, with the time-band product (TBP) being 0.598. The power instability is 0.5% (RMS) and 0.7% (RMS), respectively, for CWML and QML operation within 120 min. Furthermore, the spectral signal-to-noise ratio is about 60 dB. For the QML operation, the power instability is 0.48% (RMS) within 60 s and 0.37% (RMS) within 10 s. After frequency stabilization, the frequency fluctuation is ±100 Hz in the long-term of 1200 s, with the frequency stability (FS) calculated to be 2.44 × 10−6. It indicates that the QML fiber laser has good power stability and frequency stability.

Hybrid Raman-erbium random fiber laser with a half open cavity assisted by artificially controlled backscattering fiber reflectors

A hybrid Raman-erbium random fiber laser with a half-open cavity assisted by chirped artificially controlled backscattering fiber reflectors is presented. A combination of a 2.4 km-long dispersion compensating fiber with two highly erbium-doped fiber pieces of 5 m length were used as gain media. A single random laser emission line centered at 1553.8 nm with an optical signal to noise ratio of 47 dB were obtained when pumped at 37.5 dBm. A full width at half maximum of 1 nm and a 100% confidence level output power instability as low as 0.08 dB were measured. The utilization of the new laser cavity as a temperature and strain sensor is also experimentally studied.

Pengaruh Intensitas Matahari Terhadap Karakteristik Sel Surya Jenis Polycristaline Menggunakan Regresi Linear

Renewable energy sources have both renewable and sustainable properties and the utilization of renewable energy sources is a continuously developed alternative. One of the technologies that can utilize renewable energy is polycrystalline solar cells. Solar cells are technology that converts sunlight energy into electrical energy. This technology is very potentially applied in Indonesia that has a tropical climate, but the main problem of this system is the power instability generated. The power produced relies heavily on the intensity of the sun received by the solar panels. The intensity of the solar radiation received by the solar panels can be maximised by installing solar panels, with a precise tilt angle. In research acquired the relationship between irradiation and current correlates of R = 0.7251. From the correlation value above indicates that there is a strong link and is directly proportional between irradiation and the current obtained. The acquired Model needs to be seen its accuracy, in which case it will be used Mean Absolute Percent Error So it is obtained by 26.5%. This indicates that the model is good enough.

Research on Household Charging Optimization of Electric Vehicles Based on Smart Load

Background: With the tremendous changes in the world’s fuel structure, the Electric Vehicle (EV) has become a powerful means of mitigating energy and environmental issues. Objective: However, when an electric vehicle is connected to home, it will cause load fluctuation, which threatens the safe and smooth operation of the user's electricity. Methods: Therefore, in order to solve the problem of power instability when the electric vehicle is connected to home, this paper proposes an optimization strategy for household charging based on Smart Load (SL). Results: After the daily load fluctuation model of electric vehicle family charging is constructed, the Particle Swarm Optimization (PSO) algorithm is combined to establish the electric vehicle family charging optimization model. Conclusion: The analysis of the example shows that the proposed method can stabilize the household power, which can effectively solve the adverse effects caused by excessive fluctuation of daily load in the family.

Indicators of Electric Power Instability from Satellite Observed Nighttime Lights

Electric power services are fundamental to prosperity and economic development. Disruptions in the electricity power service can range from minutes to days. Such events are common in many developing economies, where the power generation and delivery infrastructure is often insufficient to meet demand and operational challenges. Yet, despite the large impacts, poor data availability has meant that relatively little is known about the spatial and temporal patterns of electric power reliability. Here, we explore the expressions of electric power instability recorded in temporal profiles of satellite observed surface lighting collected by the Visible Infrared Imaging Radiometer Suite (VIIRS) low light imaging day/night band (DNB). The nightly temporal profiles span from 2012 through to mid-2020 and contain more than 3000 observations, each from a total of 16 test sites from Africa, Asia, and North America. We present our findings in terms of various novel indicators. The preprocessing steps included radiometric adjustments designed to reduce variance due to the view angle and lunar illumination differences. The residual variance after the radiometric adjustments suggests the presence of a previously unidentified source of variability in the DNB observations of surface lighting. We believe that the short dwell time of the DNB pixel collections results in the vast under-sampling of the alternating current lighting flicker cycles. We tested 12 separate indices and looked for evidence of power instability. The key characteristic of lights in cities with developing electric power services is that they are quite dim, typically 5 to 10 times dimmer for the same population level as in Organization for Economic Co-operation and Development (OECD) countries. In fact, the radiances for developing cities are just slightly above the detection limit, in the range of 1 to 10 nanowatts. The clearest indicator for power loss is the percent outage. Indicators for supply adequacy include the radiance per person and the percent of population with detectable lights. The best indicator for load-shedding is annual cycling, which was found in more than half of the grid cells in two Northern India cities. Cities with frequent upward or downward radiance spikes can have anomalously high levels of variance, skew, and kurtosis. A final observation is that, barring war or catastrophic events, the year-on-year changes in lighting are quite small. Most cities are either largely stable over time, or are gradually increasing in indices such as the mean, variance, and lift, indicating a trajectory that proceeds across multiple years.

Efficient Dual-Wavelengths Continuous Mode Lasers by End-Pumping of Series Nd:YVO4 and Nd:GdVO4 Crystals and Speckle Reduction Study

In this paper, diode pumped solid state (DPSS) lasers based on end-pumping series N d : Y V O 4 and N d : G d V O 4 crystals were studied. Dual-, tri-, and quad-wavelength emissions were achieved. In the dual-wavelength emission operation, an optical-to-optical efficiency (O-O) of 48.9% and the power instability was 0.4% were obtained. These are the most efficient and compact lasers operating in continuous wave mode reported to date with series crystals. Besides this, the effect of changing power ratio between the output laser powers on speckle reduction was investigated for the first time. In addition, tri and quad wavelength emissions were achieved with a reasonable efficiency simply by optimizing the cavity parameters.

The Burden of Power: Construing Power as Responsibility (Rather Than as Opportunity) Alters Threat-Challenge Responses

Power usually lowers stress responses. In stressful situations, having high (vs. low) power heightens challenge and lowers threat. Yet, even power-holders may experience threat when becoming aware of the responsibility that accompanies their power. Power-holders can construe (i.e., understand) a high-power position primarily as opportunity to “make things happen” or as responsibility to “take care of things.” Power-holders construing power as responsibility (rather than opportunity) may be more likely to experience demands—such as taking care of important decisions under their control—as outweighing their resources, resulting in less challenge and more threat. Four experiments with subjective and cardiovascular threat-challenge indicators support this. Going beyond prior work on structural aspects (e.g., power instability) that induce stress, we show that merely the way how power-holders construe their power can evoke stress. Specifically, we find that power construed as responsibility (vs. opportunity) is more likely to imply a “burden” for the power-holder.