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Near-infrared Laser Triggered Full-Color Tuning Photon Upconversion and Intense White Emission in Single Gd2O3 Microparticle
摘要： Full-color emission fluorescence materials are of imperious demands in information storage, graphics imaging and anti-counterfeiting fields. However, it is still a formidable challenge to develop a single material with full-color emission and high purity white output under a NIR-light excitation. Herein, we design a novel and convenient strategy to tune the upconversion luminescence color with full color range in lanthanide ions doped Gd2O3 microspheres via a single NIR laser sensitization. Different from the typical ion-dependent tuning of color, the bright and flexible full-color emission tuning from blue to cyan, green, yellow, pink, and red can be controllable implementation in a single microparticle. Particularity, benefiting from the laser sensitive color adjustment, highly intense white color emission can be simultaneously achieved in diverse doped ion concentration particles. In addition, the upconversion emission intensity has been evidently improved if using a NIR laser sensitization, leading to significantly enhanced upconversion red luminescence signal (44-fold) at the power 446 mW. The mechanistic investigations and dynamics analysis reveal that the unprecedented color tunability from these microcrystals is attributed to dynamic control of multi-energy transfer and multi-cross relaxation process. Furthermore, owning to their excellent upconversion luminescence properties, Gd2O3 microparticles could be used to the anticounterfeiting application in different colors. These findings not only open a way to fabricate a single material to fine tuning upconversion emission in a full color gamut, but also give the possibility to construction of the multicolor imaging for anti-counterfeiting applications.
关键词： upconversion luminescence,anti-counterfeiting,full color emission,lanthanide ions doped Gd2O3 microspheres,white color emission,laser sensitization
更新于2025-09-16 10:30:52
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Thermoplasmonic Maskless Lithography on Upconverting Nanocomposites Assisted by Gold Nanostars
摘要： Photothermal effects in plasmonic nanoparticles can be used to locally modify temperature-sensitive materials. Polylactic acid (PLA) is a thermoplastic biodegradable polymer with a glass transition temperature around 60 ?C that has been popularized as a feedstock material for 3D printing. Here, we extend its use to produce thin PLA films that can be modified at the microscopic level when covered with gold nanostars (AuNSs). The heat dissipation generated when exciting the plasmon resonance of AuNSs, under exposure to 976 nm focused laser light, produce an increase in the local temperature of more than 100 ?C. When the temperature surpasses the glass transition of the base PLA layer, AuNSs get attached to the polymer surface. The following dissolution of the unexposed material in acetone bath permits the precise control of the engraving process at the microscale. Furthermore, Er3+ doped upconverting nanoparticles embedded into the PLA layer can act as optical nanothermometers to probe the local temperature, simultaneously allowing the visualization of the laser spot. A computer numerical control (CNC) system was developed to drive the laser writing beam and transfer 2D patterns, opening up the thermoplasmonic maskless lithography technique. Suitable for rigid and flexible substrates coated with PLA, the methods and materials developed here were applied to produce patterned substrates for surface enhanced Raman spectroscopy, and luminescent optical encoding for anti-counterfeiting technologies.
关键词： photothermal nanoparticles,gold nanostars,optical thermometry,thermoplasmonics,maskless lithography,upconversion nanoparticles
更新于2025-09-16 10:30:52
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Plasmonically Enhanced Upconversion Luminescence via Holographically Formed Silver Nanogratings
摘要： Greatly enhanced upconversion luminescence was demonstrated by integrating the core-shell upconversion nanorods with the Ag nanogratings. Both the Ag nanogratings and upconversion nanorods were fabricated/synthesized in a facile, cost-effective, high throughput way. Experimental results showed that the upconversion luminescence intensity of Er3+ in the core-shell upconversion nanorods can be well tuned and enhanced by changing the shell thickness and the period of the Ag nanograting. The underlying physical mechanism for the upconversion luminescence enhancement was attributed to the plasmonically enhanced near infrared broadband absorption of the periodic Ag nanograting and the localized surface plasmon resonance of Ag nanocrystals. The maximum enhanced factors of 523 nm, 544 nm (green emission) and 658 nm (red emission) of Er3+ ions excited at 980 nm are 3.8, 5.5 and 4.6 folds, respectively. Our fabrication approach and results suggest that such a simple integration is potentially useful for biosensing/imaging and anticounterfeiting applications.
关键词： plasmonic enhancement,upconversion,core-shell nanorod,nanograting,Holographical synthesis
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Ultra-Compact Low-Noise Broad-Band Upconversion Detector at 6 μm
摘要： State-of-the-art mid-infrared (MIR: 2 – 15 μm) direct detectors (e.g. semiconductor based HgCdTe, PbS, PbSe, and microbolometer) suffer from high background noise when operating at room temperature. Low noise detection therefore requires multi-stage or cryogenic cooling (-195°C) and perfect shielding to avoid temperature fluctuations [1]. Such systems easily become sophisticated and bulky, non-suitable for widespread applications. As the MIR spectral range, especially around 6 μm, is very relevant for spectroscopic-imaging of bio-molecules (protein, lipids), tissues (cancer, tumour), or for sensing of environmental pollutants (CH4, NO, NO2, SO2), high resolution spectroscopic systems in the 6 μm range is much in need. The numbers of pixels in typical HgCdTe or microbolometer based array detectors are limited to few 100s, making them less than ideal for fast high resolution broad-band spectroscopy. This work aims to solve that problem, by using frequency upconversion detection (UCD) [2]. In the presence of a strong near-infrared (NIR) LASER pump (at 1.03 μm), the MIR signal (6 μm) is translated to the NIR wavelength range (below 1 μm) using parametric frequency conversion in a nonlinear crystal (AgGaS2), without losing the spectral information encoded in the MIR signal. After upconversion, a standard silicon-CCD based spectrometer (pixel number = 2064) is used to detect the upconverted signal. In this way, high resolution, sensitive spectroscopic measurements can be performed, without the need for sophisticated cooling. The proposed upconversion system is based on a diode (940 nm) pumped Yb:YAG based solid state LASER operating at 1.03 μm, where the nonlinear crystal AgGaS2 (bulk, 5×5×10 mm3) is placed inside the LASER cavity to access the high intracavity power (Fig. 1(a)). This arrangement essentially gives higher upconversion efficiency. A Globar (heat source at ~ 800°C) is used as MIR illumination in the 6 μm range, giving an upconverted signal in the 880 nm range (grey area plot in Fig. 1(b)). In comparison to the previous demonstrations [3], the primary novelties of this system are (i) long-wavelength pumping of the laser, meaning that the pump diode wavelength (940 nm) is longer than the upconverted wavelength (< 900 nm), simplifying the spectral filtering of the upconverted signal, (ii) the LASER (at 1.03 μm) cavity is only 4 cm long, which makes the footprint of the upconversion module < 10 cm2, and (iii) no moving parts are needed in the upconversion spectrometer system (Fig. 1(a)). Using this system, we have successfully upconverted the 6 – 6.8 μm range (800 nm wide) within a single acquisition (50 ms) using Type-II birefringent phase matching in an AgGaS2 crystal. The wide bandwidth of the upconversion detection is achieved by exploiting non-collinear interaction between the pump LASER and the MIR signal inside the crystal. As an experimental verification we measured the MIR absorption spectrum of a polystyrene film placed at the MIR input side (Fig. 1(b)). Further details and results will be presented. We believe this is a promising route towards a small footprint, low-noise, efficient upconversion detector for high resolution spectroscopic application, directly in the molecular fingerprint wavelength range.
关键词： upconversion detection,spectroscopic-imaging,mid-infrared,environmental pollutants,nonlinear crystal
更新于2025-09-12 10:27:22
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Near-infrared boosted ROS responsive siRNA delivery and cancer therapy with sequentially peeled upconversion nano-onions
摘要： RNA interference (RNAi) therapy has become an appealing approach for cancer treatment, while the specificity and efficiency of controlled small interference RNA (siRNA) release remain challenging due to the heterogeneity of tumor environment. Herein, upconversion nano-onions (UCNOs) with stacked polymer coating layers are constructed to decompose sequentially in response to extracellular environment and NIR stimulation. The UCNOs (UCNPs-PEIRB-PEISeSe/siRNA-R8-HA) are composed of upconversion nanoparticles (UCNPs) core functionalized with inner coating layer of photosensitizer rose bengal (RB) conjugated PEI 600, middle coating layer of singlet oxygen (1O2) sensitive diselenide linked PEI 600 with therapeutic siRNA loading and cell-penetrating peptide R8 modification, and outer coating layer of negatively charged hyaluronic acid (HA). HA prevents siRNA leakage during delivery process and specifically targets tumor cells with overexpressed CD44 membrane receptors, and digested by cell secreted hyaluronidase (HAase). Upon the subsequent irradiation at 808 nm, UCNPs core generates emissions around 540 nm, which activate RB to boost ROS generation for complete PEI-SeSe decompose. The NIR boosted decompose of UCNOs induces a fast and efficient siRNA release, which effectively improves the gene silencing efficiency in vitro and suppresses tumor growth in vivo. The proposed sequentially responsive UCNOs have promising potential application in precision medicine.
关键词： Sequential response,siRNA delivery,Upconversion nano-onions (UCNOs),Reactive oxygen species (ROS)
更新于2025-09-12 10:27:22
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[IEEE 2019 21st International Conference on Transparent Optical Networks (ICTON) - Angers, France (2019.7.9-2019.7.13)] 2019 21st International Conference on Transparent Optical Networks (ICTON) - Erbium-Doped Polymer Waveguide Amplifiers for Board-Level Optical Interconnects
摘要： Optical interconnects have an important role to play in next-generation high-performance electronic systems by enabling power-efficient high-speed board-level communication links. Polymer-based optical waveguides is a leading technology for integrating optical links onto standard printed circuit boards as it is sufficiently low cost and enables cost-effective manufacturing and assembly. Various polymer-based optical backplanes have been reported in recent years enabling different on-board interconnection architectures. However, all currently demonstrated systems are purely passive, which limits therefore the reach, complexity and functionality of these on-board systems. Here, we present recent simulation and experimental studies towards the development of Er-doped polymer-based waveguide amplifiers. Two different approaches to integrate Er-doped materials in siloxane polymer are investigated: (i) ultrafast laser plasma implantation of Er-doped glasses and (ii) solution-based dispersion of Er-doped nanoparticles. Experimental and simulation results on the achievable performance from such waveguide amplifiers are presented focusing on impact of the waveguide loss and upconversion on the gain figure.
关键词： EDWA,upconversion,polymer,optical interconnect,erbium
更新于2025-09-12 10:27:22
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Tunable upconversion luminescence and optical temperature sensing based on non-thermal coupled levels of Lu3NbO7:Yb3+/Ho3+ phosphors
摘要： The color-tunable upconversion (UC) emission and optical temperature sensing based on non-thermal coupled levels (NTCL) were observed from the Yb3t/Ho3t codoped Lu3NbO7 phosphors synthesized by the solid-state method. The phosphors are capable of generating color tunable UC luminescence from green (yellow) to yellow (green) with the increase of the Yb3t concentration. The tunable emission is due to the different energy back transfer processes from Ho3t to Yb3t. The temperature sensing performances are investigated in the temperature range of 293–573 K based on NTCL by using fluorescence intensity ratio technology. The maximum absolute sensitivities are 0.37%K?1, 0.94%K?1, 0.27%K?1 at 298 K, which are based on three pairs NTCL of (5F4/5S2→5I8)/(5F5→5I8), (5F5→5I8)/(5F4/5S2→5I7) and (5F4/5S2→5I8)/(5F4/5S2→5I7) of Ho3t, respectively. The above results suggest that the as-prepared Lu3NbO7:Yb3t/Ho3t phosphors have great potential for the application prospects of upconverter, color tunable device and optical temperature sensor.
关键词： Phosphor,Optical temperature sensing,Lu3NbO7,Upconversion luminescence
更新于2025-09-11 14:15:04
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Theoretical Modelling and Experimental Demonstration of a Mid-Infrared Femtosecond Upconversion System
摘要： Mid-infrared (mid-IR) imaging and spectroscopic techniques have been rapidly evolving in recent years, primarily due to a multitude of application within diverse fields like biomedical imaging, chemical sensing and cancer diagnostics [1]. Most complex chemicals have unique spectral signatures in the mid-IR region, facilitating unambiguous identification based on their absorption features. Owing to the limitations of conventional detectors in the mid-IR spectral range, sum frequency generation (SFG) in a second order nonlinear crystal can be used to convert the mid-IR signal to the visible/near-IR, enabling easy detection using silicon-based detectors. Ultrashort-pulsed upconversion is of particular interest for performing pump-probe experiments and studies of fast relaxation dynamics of chemicals and molecules [2]. In this work, we report the first demonstration of femtosecond mid-IR upconversion imaging using SFG in the Fourier plane of a 4f imaging setup. The theory developed in [3] is not valid in the short-pulsed regime (below approximately 1 picosecond) because it does not account for the reduced interaction length in the crystal (temporal walk-off between the interacting pulses) due to group velocity mismatch (GVM). We develop a theoretical model to describe femtosecond upconversion imaging, considering the broad spectrum associated with femtosecond pulses and reduced interaction length associated with GVM. This model enables the calculation of key parameters of a short-pulsed upconversion imaging system. We find a significant increase in angular and spectral acceptance bandwidth for mid-IR signal in the short-pulsed regimes, due to drastic reduction in interaction length, resulting in exceptionally large upconversion imaging field of view (FoV) as depicted in Fig 1 (a). The resolution of the system is studied experimentally by illuminating a USAF resolution target with a mid-IR signal followed by detection of the upconverted signal. An example of an upconverted image is shown in Fig 1 (b), where a resolution of 14.2 line pair/mm is obtained.
关键词： upconversion,femtosecond,spectroscopy,imaging,mid-infrared
更新于2025-09-11 14:15:04
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Theranostic nanocomplex of gold-decorated upconversion nanoparticles for optical imaging and temperature-controlled photothermal therapy
摘要： The multifunctional hybrid nanomaterials could bring alternative solutions to current public health problems like cancer diagnosis and treatment. In this work, the near-infrared-activated NaYF4:Yb,Er up-conversion nanoparticles (UCNPs) were synthesized and covalently decorated with sub-10 nm gold nanoparticles (AuNPs) in a 10 min reaction. The UCNPs in the UCNPs-AuNPs complex converted the deep-penetrating 975 nm near-infrared photons into visible emissions, which were simultaneously used for multiple applications: i) plasmon-induced photothermal therapy, ii) in situ sensing and control of the temperature (nano-thermometer), and iii) contrast agent for fluorescence imaging and cell tracking at the tissues transparency window. The effective energy transfer of green emissions and consequent temperature increment was enhanced by the short separation between donor (UCNPs) and acceptor nanoparticles (AuNPs). The induced hyperthermia locally triggered irreversible cancer cell damage, considerably reducing the cell viability upon 5 min of NIR irradiation but being practically inert in the absence of infrared light exposure. In addition, the non-transferred fractions of the 525 and 545 nm green emission bands were suitable for the ratiometric temperature sensing in a physiologically relevant range (25–50 °C), which allowed to accurately monitor and control the heat generation during the photothermal therapy application (with effective temperature increase from 37 up to 45 °C). Since the 659 nm red emission was only slightly affected by the attached-gold nanospheres, the UCNPs-AuNPs nanocomplex were used to track the MCF-7 breast cancer cells. The simplicity and functionality of this nanocomplex make it an attractive alternative for simultaneous breast cancer detection and temperature-controlled photothermal therapy.
关键词： Nano-thermometer,Breast cancer,Upconversion nanoparticles,Photothermal therapy,Theranostics
更新于2025-09-11 14:15:04
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Triplet–triplet upconversion enhanced by spin–orbit coupling in organic light-emitting diodes
摘要： Triplet–triplet upconversion, in which two triplet excitons are converted to one singlet exciton, is a well-known approach to exceed the limit of electroluminescence quantum efficiency in conventional fluorescence-based organic light-emitting diodes. Considering the spin multiplicity of triplet pairs, upconversion efficiency is usually limited to 20%. Although this limit can be exceeded when the energy of a triplet pair is lower than that of a second triplet excited state, such as for rubrene, it is generally difficult to engineer the energy levels of higher triplet excited states. Here, we investigate the upconversion efficiency of a series of new anthracene derivatives with different substituents. Some of these derivatives show upconversion efficiencies close to 50% even though the calculated energy levels of the second triplet excited states are lower than twice the lowest triplet energy. A possible upconversion mechanism is proposed based on the molecular structures and quantum chemical calculations.
关键词： Triplet–triplet upconversion,spin–orbit coupling,anthracene derivatives,quantum chemical calculations,organic light-emitting diodes
更新于2025-09-11 14:15:04