Influence of spectrum characteristics on the output efficiency of LED pump laser

Using a fiber of that is 125 μm in diameter in rhodamine 6G ethanol solution, controllable multi- and single-whispering-gallery-mode (WGM) optofluidic lasers based on evanescent-wave-coupled gain are both available. With multi-mode WGM emission, lasing emission with almost pure TM (transverse magnetic) or almost TE (transverse electric) modes can be obtained when the pump laser has an electric field parallel (perpendicular) to the fiber axis, i.e., the polarization direction of output laser is the same as that of the pump laser. On the other hand, when the laser emission is single-mode, the TE output laser always emerges firstly above lasing threshold, then keeps TE mode while the pump laser’s intensity increases with polarization direction perpendicular to the fiber axis; on the contrary, TE emission will dwindle relatively, while the TM emission emerges and dominates the spectra, when the pump laser’s intensity increases with polarization parallel to the fiber axis. Our work proves that controlling the leakage of the evanescent wave from high-Q microcavities is crucial for both modes of lasing emission and its polarization.

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A Temoo FIR Laser with Integrated Pump Laser

1979 International Conference on Submillimeter Waves and Their Applications ◽

10.1109/icswa.1979.9335350 ◽

1979 ◽

Author(s):

M. Tacke ◽

P. Dyrna

Keyword(s):

Pump Laser ◽

Fir Laser

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A method for studying pico to microsecond time-resolved core-level spectroscopy used to investigate electron dynamics in quantum dots

Scientific Reports ◽

10.1038/s41598-020-79792-z ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Tamara Sloboda ◽

Sebastian Svanström ◽

Fredrik O. L. Johansson ◽

Aneta Andruszkiewicz ◽

Xiaoliang Zhang ◽

...

Keyword(s):

Quantum Dots ◽

Electron Injection ◽

Core Level ◽

Pump Laser ◽

Repetition Frequency ◽

Specific Information ◽

Single Experiment ◽

Time Resolved ◽

X Ray ◽

Pbs Quantum Dots

AbstractTime-resolved photoelectron spectroscopy can give insights into carrier dynamics and offers the possibility of element and site-specific information through the measurements of core levels. In this paper, we demonstrate that this method can access electrons dynamics in PbS quantum dots over a wide time window spanning from pico- to microseconds in a single experiment carried out at the synchrotron facility BESSY II. The method is sensitive to small changes in core level positions. Fast measurements at low pump fluences are enabled by the use of a pump laser at a lower repetition frequency than the repetition frequency of the X-ray pulses used to probe the core level electrons: Through the use of a time-resolved spectrometer, time-dependent analysis of data from all synchrotron pulses is possible. Furthermore, by picosecond control of the pump laser arrival at the sample relative to the X-ray pulses, a time-resolution limited only by the length of the X-ray pulses is achieved. Using this method, we studied the charge dynamics in thin film samples of PbS quantum dots on n-type MgZnO substrates through time-resolved measurements of the Pb 5d core level. We found a time-resolved core level shift, which we could assign to electron injection and charge accumulation at the MgZnO/PbS quantum dots interface. This assignment was confirmed through the measurement of PbS films with different thicknesses. Our results therefore give insight into the magnitude of the photovoltage generated specifically at the MgZnO/PbS interface and into the timescale of charge transport and electron injection, as well as into the timescale of charge recombination at this interface. It is a unique feature of our method that the timescale of both these processes can be accessed in a single experiment and investigated for a specific interface.

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Public–Private Partnership Infrastructure Investment and Sustainable Economic Development: An Empirical Study Based on Efficiency Evaluation and Spatial Spillover in China

Sustainability ◽

10.3390/su13158146 ◽

2021 ◽

Vol 13 (15) ◽

pp. 8146

Author(s):

Bingyao Chen

Keyword(s):

Economic Development ◽

Infrastructure Investment ◽

Economic Sustainability ◽

Regional Economies ◽

Input Output ◽

Private Partnership ◽

Spatial Spillover ◽

Sustainable Economic Development ◽

Output Efficiency ◽

Industrial Heterogeneity

Public–private partnership (PPP), an innovative mode of infrastructure investment, has been widely applied in China and has become an essential policy tool with which to promote sustainable economic development. In order to comprehensively evaluate the economic consequences, using 31 provinces in China from 2003 to 2018 as samples, first, stochastic frontier analysis was performed to measure the input–output efficiency of infrastructure investment to evaluate the economic sustainability and efficiency of PPP compared to single government-led investment mode. Next, the overall economic growth effect of PPP was verified. Further, from the perspective of sustainable development of regional economies, the double-fixed effect spatial Durbin model was adopted to empirically test the spatial spillover effect of PPP and clarify its industrial heterogeneity. The results show the following. (1) The average input–output efficiency of infrastructure is 0.449, revealing a distribution law of decreasing from east to west and remarkable regional variation. However, a good trend of improvement emerged, reflecting the economic sustainability of infrastructure investment, and PPP has played a positive role in promoting it. (2) PPP has significant and positive economic growth and spatial spillover effects, which can promote regional economic integration, embodying its economic sustainability function. (3) The economic impact of PPP has significant industrial heterogeneity. Transportation PPP can bring greater economic benefits, confirming the vital position of transportation infrastructure in the sustainable development of regional economies. Energy and water PPPs have positive externalities. All of this provides powerful and reliable proof of the realization of sustainable economic development under the regional virtuous circle driven by infrastructure investment through PPP.

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Pump Laser Automatic Signal Control for Erbium-Doped Fiber Amplifier Gain, Noise Figure, and Output Spectral Power

Journal of Optical Communications ◽

10.1515/joc-2019-0203 ◽

2019 ◽

Vol 0 (0) ◽

Author(s):

I. S. Amiri ◽

Ahmed Nabih Zaki Rashed ◽

P. Yupapin

Keyword(s):

Noise Figure ◽

Spectral Power ◽

Power Level ◽

Fiber Amplifier ◽

Pump Laser ◽

Output Power Level ◽

Signal Control ◽

Erbium Doped Fiber Amplifier ◽

Erbium Doped ◽

Amplifier Gain

AbstractThis paper has simulated the pump laser automatic signal control for erbium-doped fiber amplifier gain, noise figure, and output spectral power. Signal gain and noise figure are deeply studied in relation to laser pump power variations at operating pumping wavelengths of 980 nm and 1,480 nm for previous and proposed models. Similar to the study of the light signal to noise ratio, output power level and maximum Q factor are also simulated versus EDFA amplifier length at pumping power of 500 mW and different pumping wavelength by using the proposed model. The obtained results are better by using a pumping wavelength of 1,480 nm than a pumping wavelength of 980 nm. The optimum EDFA amplifier is 5 m, which gives better performance than other amplifier lengths.

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Radiofrequency Exposure in Schools' Environment Reveals Spectrum Characteristics: The Role of Public Information

Bioelectromagnetics ◽

10.1002/bem.22286 ◽

2020 ◽

Vol 41 (7) ◽

pp. 558-564

Author(s):

Charilaos Tyrakis ◽

Georgios A. Gourzoulidis ◽

Yiannis Kiouvrekis ◽

Aris Alexias ◽

Mohammed Alkhorayef ◽

...

Keyword(s):

Public Information ◽

Spectrum Characteristics

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