scholarly journals Pumping-controlled multicolor modulation of upconversion emission for dual-mode dynamic anti-counterfeiting

Nanophotonics ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 1519-1528
Author(s):  
Xiaoru Dai ◽  
Ke Wang ◽  
Lei Lei ◽  
Shiqing Xu ◽  
Yao Cheng ◽  
...  
Keyword(s):  
Photon Number ◽  
Upconversion Emission ◽  
Excitation Power ◽  
Color Variation ◽  
Excitation Power Density ◽  
Dual Mode ◽  
Emission Color ◽  
Ultrahigh Sensitivity ◽  
Infrared Excitation ◽  
The Difference

AbstractLanthanide up-conversion features stepwise multi-photon processes, where the difference in photon number that is required for specific up-conversion process usually leads to significant variance in pumping-related processes/properties. In this work, a pumping-controlled dual-mode anti-counterfeiting strategy is conceived by taking advantage of the combination of up-conversion processes with different photon numbers. The combination of Er3+ and Tm3+, which are spatially separated within a designed core/triple-shell nano-architecture, is taken as an example to illustrate such idea. Upon infrared excitation, the emission color of a designed pattern can be switched from red to purple by increasing the excitation power density from 5 to 11 W/cm2, while a bright luminescent trajectory including red, white and blue-green color with different length is observed when rotating the pattern above 600 rpm. In addition, the relative up-conversion emission intensities of the Er3+ and Tm3+ ions can be manipulated through tailoring interfacial or inner defects in the core/triple-shell nano-crystals, which enable an ultrahigh sensitivity for the pumping-controlled emission color variation to be observed under excitation power well below 11 W/cm2.

scholarly journals Threshold increase and lasing inhibition due to hexagonal-pyramid-shaped hillocks in AlGaN-based DUV laser diodes on single-crystal AlN substrate

2021 ◽  
Author(s):  
Maki Kushimoto ◽  
Ziyi Zhang ◽  
Yoshio HONDA ◽  
Leo John Schowalter ◽  
Chiaki Sasaoka ◽  
...  
Keyword(s):  
Imaging Techniques ◽  
Laser Diodes ◽  
Optical Excitation ◽  
Threshold Current ◽  
Excitation Power ◽  
Threshold Current Density ◽  
Excitation Power Density ◽  
Threshold Excitation ◽  
The Difference ◽  
Hexagonal Pyramid

Abstract The presence of hexagonal-pyramid-shaped hillocks (HPHs) in AlGaN epitaxial films affects device character- istics; this effect is significant in DUV laser diodes (LDs) on AlN substrates, where the presence of HPHs under the p-electrode increases the threshold current density and inhibits the lasing. In this study, we investigated the difference between the lasing characteristics of LDs with and without HPHs. It was found that in the presence of HPHs, the threshold excitation power density increased and the slope efficiency decreased by optical excitation. To investigate the cause of these phenomena, we performed structural, optical, and electrical analyses of the HPHs. Various imaging techniques were used to directly capture the characteristics of the HPHs. As a result, we concluded that HPHs cause the degradation of LD characteristics due to a combination of structural, optical, and electrical factors.

Optical Temperature Sensor Based on Infrared Excited Green Upconversion Emission in Hexagonal Phase NaLuF4:Yb3+/Er3+ Nanorods

2016 ◽  
Vol 16 (4) ◽  
pp. 3641-3645 ◽  
Author(s):  
Dongyu Li ◽  
Linlin Tian ◽  
Zhen Huang ◽  
Lexi Shao ◽  
Jun Quan ◽  
...  
Keyword(s):  
Temperature Sensor ◽  
Hexagonal Phase ◽  
Upconversion Emission ◽  
Excitation Power ◽  
Temperature Sensitive ◽  
Potential Candidate ◽  
Excitation Power Density ◽  
Fluorescence Intensity Ratio ◽  
Optical Temperature Sensor ◽  
Upconversion Emissions

Hexagonal phase NaLuF4:Yb3+/Er3+ nanorods were synthesized hydrothermally. An analysis of the intense green upconversion emissions at 525 nm and 550 nm in hexagonal phase NaLuF4:Yb3/+Er3+ nanorods under excitation power density of 4.2 W/cm2 available from a diode laser emitting at 976 nm, have been undertaken. Fluorescence intensity ratio (FIR) variation of temperature-sensitive green upconversion emissions at 525 nm and 550 nm in this material was recorded in the physiological range from 295 to 343 K. The maximum sensitivity derived from the FIR technique of the green upconversion emissions is approximately 0.0044 K−1. Experimental results implied that hexagonal phase NaLuF4:Yb3/+Er3+ nanorods was a potential candidate for optical temperature sensor.

A method for correcting the excitation power density dependence of upconversion emission due to laser-induced heating

2018 ◽  
Vol 82 ◽  
pp. 65-70 ◽  
Author(s):  
Reetu E. Joseph ◽  
Dmitry Busko ◽  
Damien Hudry ◽  
Guojun Gao ◽  
Daniel Biner ◽  
...  
Keyword(s):  
Density Dependence ◽  
Power Density ◽  
Upconversion Emission ◽  
Excitation Power ◽  
Excitation Power Density

Surface Emission of InxGa1-x N/GaN Espaliers Grown by MOCVD under Different Optical Excitation

2012 ◽  
Vol 442 ◽  
pp. 393-397
Author(s):  
You Zhang Zhu ◽  
Yan Liu ◽  
Hong Xia Wang ◽  
Zhen Sun ◽  
Jin She Yuan
Keyword(s):  
Power Density ◽  
Chemical Vapor ◽  
Optical Excitation ◽  
Excitation Power ◽  
Organic Chemical ◽  
Light Sources ◽  
Excitation Power Density ◽  
Transmission Spectra ◽  
Surface Emission ◽  
The Difference

Photoluminescence properties of InGaN film grown on sapphire substrates by metal organic chemical vapor deposition(MOCVD) was experimentally Investigation. The x-ray diffraction(XRD), transmission spectra, PL spectrum were used. The result of XRD shows that the mole composition of In in the InGaN film is estimated be 0.2 approximately. The band gap of the sample is calculated to be 2.66eV. A clear oscillation from F-P cavity could be observed on transmission spectra. There are three main peaks from the surface emission InGaN espaliers being excited on different light sources and different excitation power density. which can be explained the broad PL come from the difference of In composition modulated by was modulated due to F-P cavity arising from surface of sample. . It is found that there is some relationship between the position of the peaks in the PL spectra, the wavelength and intensity of power density and the F-P cavity.PACS: 73.61.

The sensitization of laser-induced heat of Er3+ doped Y2O3 nanocrystals by codoped with Mn2+

2015 ◽  
Vol 29 (22) ◽  
pp. 1550158
Author(s):  
Yunfeng Bai ◽  
Minjie Luan ◽  
Linjun Li ◽  
Zhelong He ◽  
Dongyu Li
Keyword(s):  
Power Density ◽  
Thermal Emission ◽  
Energy Levels ◽  
Excitation Power ◽  
Threshold Power ◽  
Excitation Power Density ◽  
Ir Laser ◽  
Order Of Magnitude ◽  
Low Threshold ◽  
Density Threshold

Low threshold power density cw laser-induced heat has been observed in [Formula: see text] and [Formula: see text] codoped [Formula: see text] nanocrystals under excitation by a 980 nm IR laser. Codoped [Formula: see text] remarkably reduces the power density threshold of laser-induced heat compared with [Formula: see text] doped [Formula: see text] nanocrystals. When the excitation power density exceed [Formula: see text], [Formula: see text] codoped [Formula: see text] nanocrystals emit strong blackbody radiation. The thermal emission of [Formula: see text] should originate from the multiphonon relaxation between neighboring energy levels. One additional UC-PL enhancement is observed. The UC-PL intensity can be enhanced by an order of magnitude through high temperature calcination caused by light into heat.

scholarly journals The Optical Properties of InGaN/GaN Nanorods Fabricated on (-201) β-Ga2O3 Substrate for Vertical Light Emitting Diodes

Photonics ◽  
2021 ◽  
Vol 8 (2) ◽  
pp. 42
Author(s):  
Jie Zhao ◽  
Weijiang Li ◽  
Lulu Wang ◽  
Xuecheng Wei ◽  
Junxi Wang ◽  
...  
Keyword(s):  
Stark Effect ◽  
Light Emitting Diodes ◽  
Light Emitting Diode ◽  
Strain Relaxation ◽  
Blue Shift ◽  
Peak Position ◽  
Excitation Power ◽  
Light Extraction Efficiency ◽  
Excitation Power Density ◽  
Light Emitting

We fabricated InGaN/GaN nanorod light emitting diode (LED) on (-201) β-Ga2O3 substrate via the SiO2 nanosphere lithography and dry-etching techniques. The InGaN/GaN nanorod LED grown on β-Ga2O3 can effectively suppress quantum confined Stark effect (QCSE) compared to planar LED on account of the strain relaxation. With the enhancement of excitation power density, the photoluminescence (PL) peak shows a large blue-shift for the planar LED, while for the nanorod LED, the peak position shift is small. Furthermore, the simulations also show that the light extraction efficiency (LEE) of the nanorod LED is approximately seven times as high as that of the planar LED. Obviously, the InGaN/GaN/β-Ga2O3 nanorod LED is conducive to improving the optical performance relative to planar LED, and the present work may lay the groundwork for future development of the GaN-based vertical light emitting diodes (VLEDs) on β-Ga2O3 substrate.

UV Emission Mechanisms in Quaternary AlInGaN Epilayers and Multiple Quantum Wells

2002 ◽  
Vol 722 ◽  
Author(s):  
Mee-Yi Ryu ◽  
C. Q. Chen ◽  
E. Kuokstis ◽  
J. W. Yang ◽  
G. Simin ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Light Emitting Diode ◽  
Chemical Vapor ◽  
Excitation Power ◽  
Multiple Quantum Wells ◽  
Multiple Quantum ◽  
Excitation Power Density ◽  
Light Emitting ◽  
Uv Emission ◽  
Alloy Disorder

AbstractWe present the results on investigation and analysis of photoluminescence (PL) dynamics of quaternary AlInGaN epilayers and AlInGaN/AlInGaN multiple quantum wells (MQWs) grown by a novel pulsed metalorganic chemical vapor deposition (PMOCVD). The emission peaks in both AlInGaN epilayers and MQWs show a blueshift with increasing excitation power density. The PL emission of quaternary samples is attributed to recombination of carriers/excitons localized at band-tail states. The PL decay time increases with decreasing emission photon energy, which is a characteristic of localized carrier/exciton recombination due to alloy disorder. The obtained properties of AlInGaN materials grown by a PMOCVD are similar to those of InGaN. This indicates that the AlInGaN system is promising for ultraviolet applications such as the InGaN system for blue light emitting diode and laser diode applications.

Homodyne-like detection scheme based on photon-number-resolving detectors

2017 ◽  
Vol 15 (08) ◽  
pp. 1740016 ◽  
Author(s):  
Alessia Allevi ◽  
Matteo Bina ◽  
Stefano Olivares ◽  
Maria Bondani
Keyword(s):  
Coherent States ◽  
Beam Splitter ◽  
Photon Number ◽  
Local Oscillator ◽  
Quantum States ◽  
Homodyne Detection ◽  
Detection Scheme ◽  
Light Signals ◽  
The Difference ◽  
Signal Field

Homodyne detection is the most effective detection scheme employed in quantum optics to characterize quantum states. It is based on mixing at a beam splitter the signal to be measured with a coherent state, called the “local oscillator,” and on evaluating the difference of the photocurrents of two photodiodes measuring the outputs of the beam splitter. If the local oscillator is much more intense than the field to be measured, the homodyne signal is proportional to the signal-field quadratures. If the local oscillator is less intense, the photodiodes can be replaced with photon-number-resolving detectors, which have a smaller dynamics but can measure the light statistics. The resulting new homodyne-like detector acquires a hybrid nature, being it capable of yielding information on both the particle-like (statistics) and wave-like (phase) properties of light signals. The scheme has been tested in the measurement of the quadratures of coherent states, bracket states and phase-averaged coherent states at different intensities of the local oscillator.

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