Duty Ratio Thresholds for Regular Transmission at Human Tissue of Near-Infrared Square-Wave Pulse

2013 ◽  
Vol 333-335 ◽  
pp. 555-558
Author(s):  
Jian Wang ◽  
Shuo Guo Li
Keyword(s):  
Experimental Study ◽  
Human Tissue ◽  
Near Infrared ◽  
Transmission Mechanism ◽  
Duty Ratio ◽  
Human Hand ◽  
Light Emitting ◽  
Wave Pulse ◽  
Square Wave ◽  
Important Index

In order to understand the transmission mechanism at human tissue of near-infrared square-wave pulse (NIRSP), an experimental study of the duty ratio threshold for regular transmission at the fingertip and palm of human hand by NIRSP was carried out by using a couple of simple transmitting and receiving device with tunable duty ratios, and also the light emitting diodes (LED) both at the wavelengths of 850 nm and 940 nm. The thresholds were determined by measuring the waveforms of the changed voltages of NIRSP receiving system as a measurement of the transmission at human tissue. When the receiving waveforms were taken on the certain behavior as the emitting waveforms, the duty ratio threshold for regular transmission at human tissue of NIRSP was observed. The experimental results show that the duty ratio is an important index for the transmission at human tissue of NIRSP. And the duty ratio thresholds for regular transmission both at the fingertip and palm of NIRSP at the wavelength of 850 nm and 940 nm have been given.

Catalyst Halogenation Enables Rapid and Efficient Polymerizations with Visible to Near-Infrared Light

2020 ◽  
Author(s):  
Alex Stafford ◽  
Dowon Ahn ◽  
Emily Raulerson ◽  
Kun-You Chung ◽  
Kaihong Sun ◽  
...  
Keyword(s):  
Near Infrared ◽  
Transient Absorption ◽  
Reaction Times ◽  
Infrared Light ◽  
Structure Property ◽  
Light Emitting ◽  
Structure Property Relationships ◽  
Nir Light ◽  
Light Intensities ◽  
Emission Quenching

Driving rapid polymerizations with visible to near-infrared (NIR) light will enable nascent technologies in the emerging fields of bio- and composite-printing. However, current photopolymerization strategies are limited by long reaction times, high light intensities, and/or large catalyst loadings. Improving efficiency remains elusive without a comprehensive, mechanistic evaluation of photocatalysis to better understand how composition relates to polymerization metrics. With this objective in mind, a series of methine- and aza-bridged boron dipyrromethene (BODIPY) derivatives were synthesized and systematically characterized to elucidate key structure-property relationships that facilitate efficient photopolymerization driven by visible to NIR light. For both BODIPY scaffolds, halogenation was shown as a general method to increase polymerization rate, quantitatively characterized using a custom real-time infrared spectroscopy setup. Furthermore, a combination of steady-state emission quenching experiments, electronic structure calculations, and ultrafast transient absorption revealed that efficient intersystem crossing to the lowest excited triplet state upon halogenation was a key mechanistic step to achieving rapid photopolymerization reactions. Unprecedented polymerization rates were achieved with extremely low light intensities (< 1 mW/cm<sup>2</sup>) and catalyst loadings (< 50 μM), exemplified by reaction completion within 60 seconds of irradiation using green, red, and NIR light-emitting diodes.

Geometrically isomeric [Ir(iqbt)(ppy)(hpa)] complexes with differential molecule orientations for efficient near-infrared (NIR) polymer light-emitting diodes (PLEDs)

2021 ◽  
Vol 9 (36) ◽  
pp. 12068-12072
Author(s):  
Wentao Li ◽  
Jiaxiang Liu ◽  
Baowen Wang ◽  
Siyu Hou ◽  
Xingqiang Lü ◽  
...  
Keyword(s):  
Near Infrared ◽  
Light Emitting Diodes ◽  
Dipole Transition ◽  
Transition Dipole ◽  
Light Emitting ◽  
Horizontal Orientation ◽  
Polymer Light Emitting Diodes

Based on geometrical isomerisation of [Ir(C^N1)(C^N2)((N^O))]-tris-heteroleptic Ir(iii)-complexes, the augmented transition dipole transition (TMD) with a preferential horizontal orientation, which is beneficial for their NIR-phosphorescence, is reported.

Ab Initio Two-sites Occupancy and Broadband Near-Infrared Emission of Cr3+ in Li2MgZrO4

2021 ◽  
Author(s):  
Xue Zhou ◽  
Jinmeng Xiang ◽  
Jiming Zheng ◽  
Xiaoqi Zhao ◽  
Hao Suo ◽  
...  
Keyword(s):  
Plant Growth ◽  
Ab Initio ◽  
Light Source ◽  
Near Infrared ◽  
Broad Band ◽  
Infrared Emission ◽  
Night Vision ◽  
Light Emitting ◽  
Non Destructive ◽  
Near Infrared Emission

Near-infrared (NIR) phosphor-converted light-emitting diodes (pc-LEDs) light source have great potential in non-destructive detection, promoting plant growth and night vision applications, while the discovery of a broad-band NIR phosphor still...

Enhanced Near‐Infrared Perovskite Light‐Emitting Devices by Introducing Choline Chloride Layer

2021 ◽  
pp. 2100636
Author(s):  
Xiaoxiao Xu ◽  
Ke Xiao ◽  
Guozhi Hou ◽  
Yangyi Zhang ◽  
Ting Zhu ◽  
...  
Keyword(s):  
Near Infrared ◽  
Choline Chloride ◽  
Light Emitting ◽  
Light Emitting Devices

scholarly journals Near-infrared lead chalcogenide quantum dots: Synthesis and applications in light emitting diodes

2019 ◽  
Vol 28 (12) ◽  
pp. 128504 ◽  
Author(s):  
Haochen Liu ◽  
Huaying Zhong ◽  
Fankai Zheng ◽  
Yue Xie ◽  
Depeng Li ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Near Infrared ◽  
Light Emitting Diodes ◽  
Lead Chalcogenide ◽  
Light Emitting

scholarly journals Two-dimensional perovskites with alternating cations in the interlayer space for stable light-emitting diodes

Nanophotonics ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Yiyue Zhang ◽  
Masoumeh Keshavarz ◽  
Elke Debroye ◽  
Eduard Fron ◽  
Miriam Candelaria Rodríguez González ◽  
...  
Keyword(s):  
Thin Films ◽  
Near Infrared ◽  
Light Emitting Diodes ◽  
Interlayer Space ◽  
High Current Density ◽  
Operational Stability ◽  
Infrared Light ◽  
Two Dimensional ◽  
Commercial Development ◽  
Light Emitting

Abstract Lead halide perovskites have attracted tremendous attention in photovoltaics due to their impressive optoelectronic properties. However, the poor stability of perovskite-based devices remains a bottleneck for further commercial development. Two-dimensional perovskites have great potential in optoelectronic devices, as they are much more stable than their three-dimensional counterparts and rapidly catching up in performance. Herein, we demonstrate high-quality two-dimensional novel perovskite thin films with alternating cations in the interlayer space. This innovative perovskite provides highly stable semiconductor thin films for efficient near-infrared light-emitting diodes (LEDs). Highly efficient LEDs with tunable emission wavelengths from 680 to 770 nm along with excellent operational stability are demonstrated by varying the thickness of the interlayer spacer cation. Furthermore, the best-performing device exhibits an external quantum efficiency of 3.4% at a high current density (J) of 249 mA/cm2 and remains above 2.5% for a J up to 720 mA cm−2, leading to a high radiance of 77.5 W/Sr m2 when driven at 6 V. The same device also shows impressive operational stability, retaining almost 80% of its initial performance after operating at 20 mA/cm2 for 350 min. This work provides fundamental evidence that this novel alternating interlayer cation 2D perovskite can be a promising and stable photonic emitter.

Electrically driven single microribbon based near-infrared exciton-polariton light-emitting diode

CrystEngComm ◽  
2021 ◽  
Author(s):  
Mingming Jiang ◽  
Fupeng Zhang ◽  
Kai Tang ◽  
Peng Wan ◽  
Caixia Kan
Keyword(s):  
High Performance ◽  
Near Infrared ◽  
Light Emitting Diodes ◽  
Light Emitting Diode ◽  
Light Sources ◽  
Coherent Light ◽  
Light Emitting ◽  
Exciton Polaritons ◽  
Laser Devices

Achieving electrically-driven exciton-polaritons has drawn substantial attention toward developing ultralow-threshold coherent light sources, containing polariton laser devices and high-performance light-emitting diodes (LEDs). In this work, we demonstrate an electrically driven...

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