Solid-state Sources Research Articles

Broadband stimulated Raman hyperspectral imaging of cells and semiconductors with synchronized fiber and solid-state sources

Broadband stimulated Raman hyperspectral imaging of cells and semiconductors with synchronized fiber and solid-state sources

Калибровка внутренних эталонов шумового сигнала радиометра по внешним источникам Igor A.

The possibility of using solid-state noise signal sources as internal standards in a two-stop modulation radiometer is discussed. The dependence of the accuracy of radiometric measurements on the temperatures of internal noise standards is estimated. The possibility of calibrating internal solid-state noise sources against external reference objects with known noise temperatures is being investigated. Formulas for calculating the noise temperatures of internal standards based on known temperatures of external standards are given. The prospect of using a new method of calibration of internal standards to improve the accuracy and stability of radiometric sensing of soils for remote determination of moisture content and soil surface temperature as an element of a precision farming system is analyzed.

A coaxial solid state nonlinear pulse forming line with an exponentially tapered ferrite composite core.

The need to optimize size, weight, and power of high-power microwave (HPM) systems has motivated the development of solid-state HPM sources, such as nonlinear transmission lines (NLTLs), which utilize gyromagnetic precession or dispersion to generate RF. One recent development implemented the NLTL as a pulse forming line (PFL) to form a nonlinear pulse forming line (NPFL) system that substantially reduced the system's size by eliminating the need for a separate PFL; however, matching standard loads can be challenging. This paper describes the development of a tapered NPFL using an exponentially tapered composite based ferrite core containing 60% nickel zinc ferrite (by volume) encased in polydimethylsiloxane (PDMS) and encapsulated in a 5% barium strontium titanate shell. The tapers exponentially change the line's impedance from a 50Ω standard HN connection to 25Ω before tapering back to 50Ω. We characterized the core behavior by obtaining magnetization curves and ferromagnetic resonance measurements. The rise time (10%-90%) of the pulse decreased from ∼6ns for 5kV charging voltage to 1.8ns for 15kV charging voltage. Under unbiased conditions, the system generated HPM with a center frequency of ∼850MHz with a 3 dB bandwidth of 125MHz. Magnetic biases of 15 and 25 kA/m increased the modulation depth and decreased the center frequency to ∼500MHz for 15kV charging voltage.

Design and Experiment of Electromagnetic Pulse Protection Circuit for RF Front End

Abstract This paper introduces the structure and working principle of electromagnetic pulse protection circuit in VHF frequency band in detail. Based on this, a protection circuit with multilevel filtering and transient suppression function is designed. The filter function of the device is realized through a five-order coaxial filter, while the transient suppression feature is accomplished using TVS devices. In order to guarantee the power capacity, the input and output ports of the circuit use N-type connector. Due to good design, the operating bandwidth of the protection circuit exceeds 1.3GHz and the insertion loss is less than 0.5dB. The protective performance of this device was tested by sub-nanosecond solid-state pulse source. The experimental results show that the peak power of electromagnetic protection circuit is greater than 700kW, the suppression capacity is more than 33dB, and the response time is better than 1.4ns.

Preparation of Multi-Layer Graphene Using Nitrogen-Doped Ultrananocrystalline Diamond as a Solid-State Carbon Source

Preparation of Multi-Layer Graphene Using Nitrogen-Doped Ultrananocrystalline Diamond as a Solid-State Carbon Source

Dynamic Nuclear Polarization with P1 Centers in Diamond.

Substitutional nitrogen impurities within the diamond lattice, known as P1 centers, have unpaired electrons that can mediate microwave driven dynamic nuclear polarization (DNP). In this paper we explore DNP of the bulk 13C spins in micrometer-sized P1 diamond particles and demonstrate a 550-fold DNP enhancement of the bulk 13C spins at room temperature in a 9 T magnetic field or 250 GHz for g ≈ 2 electrons. We study the DNP mechanisms, exploring their dependence on sample spinning frequency and microwave irradiation frequency using both continuous wave and frequency swept microwave irradiation, and discuss the results alongside recent DNP studies in the literature. Even with a modest microwave irradiation power of 160 mW from our frequency swept solid-state microwave source, we achieve a significant 13C signal enhancement, ε = 270 at room temperature. The enhancements were found to increase with the magic angle spinning (MAS) frequency, ωr/2π, and the results provide mechanistic insights into how different electron populations contribute to the observed DNP efficiency. These findings are inherently interesting and of practical importance in view of the recently reported diamond rotors fabricated from P1 high-pressure, high-temperature (HPHT) diamond.

Research on the Flicker Effect in Modern Light Sources Powered by an Electrical Network

Disruptions in power quality have a negative impact on many energy consumers. These include lighting, where interference manifests itself, among others, in the form of light flickering. The article presents phenomena accompanying the operation of modern light sources against the background of exemplary results of studies on the flicker of conventional light sources, such as incandescent or fluorescent lamps. The flickering effect of light generated in modern lamps can occur under stable voltage conditions in the supply network. The main subjects of the conducted research were solid-state light sources—light-emitting diode (LED) lamps, currently available on the lighting market. To assess the effects of these phenomena, it is necessary to use measures other than those traditionally used. The method used allows for the measurement of flicker resulting from both power supply disturbances and the properties of modern light sources. Using the developed measurement system, it is possible to record temporal changes in flicker coefficients resulting from, for example, changing supply voltage conditions. Due to the possibility of flickering light from sources offered by different manufacturers, as shown by research, it is advisable to carry out measurements at the place of use of the lighting.

Red-shift of the photoluminescent emission and enhancement of the internal quantum efficiency by co-doping Gd3+ in Tb3Al5O12: Ce3+ phosphors for warm WLEDs

White Light Emitting Diodes (WLEDs) are widely used in our lives as the fourth generation of solid-state lighting sources. However, the phosphors in the WLEDs device lack a red component, resulting in a cool white light, which affects the quality of lighting while damaging the user's eyesight. In this work, the Tb3Al5O12: Ce3+ (TAG: Ce3+) and Tb3Al5O12: Ce3+, Gd3+ (TAG: Ce3+, Gd3+) phosphors were synthesized by sol-gel method. Powder X-ray diffraction analysis confirmed the successful substitution of Ce3+ and Gd3+ in the system, as evidenced by the quantifiable expansion of the unit cell volume when Tb3+ was replaced with Ce3+ and Gd3+. As the increasing of Gd3+ doping concentration in the TAG: 0.025Ce3+, yGd3+ phosphors, the emission peak of Ce3+ (arises from the 5d→4f transition) shifted from 565 nm to 580 nm. The photoluminescence emission intensity of TAG: 0.025Ce3+, 0.6Gd3+ phosphor can be increased by about 192 % compared to TAG: 0.025Ce3+ phosphor (y = 0). The Gd3+-to-Ce3+ energy transfer is robustly supported by the prolonged lifetime of Ce3+ with an increase in Gd3+ content in TAG: 0.025Ce3+, yGd3+. Notably, the energy transfer process from Gd3+ to Ce3+ effectively enhanced the internal quantum efficiency (IQE) of the TAG: 0.025Ce3+, yGd3+ phosphors, up to 70.14 %. Variable-temperature emission spectra indicates that TAG: Ce3+, Gd3+ phosphors prepared by the sol-gel method have excellent luminescent thermal stability. Ultimately, the WLEDs devices assembled with TAG: Ce3+, Gd3+ phosphors can produce warm white light, which indicates that TAG: Ce3+, Gd3+ phosphors are a potential material for warm WLEDs.

A novel high-brightness and thermally-stable red phosphor Ca2GaNbO6: Eu3+ for WLEDs and anti-counterfeiting inks

There is a significant demand for phosphorescent white light-emitting diodes (WLEDs) with high color rendering index (CRI) and low correlated color temperature (CCT) as solid-state lighting sources due to their environmental friendliness. In this study, a novel ultraviolet (UV)-excited Eu3+-activated Ca2GaNbO6 phosphor was meticulously synthesized by a high-temperature solid-state method, which led to the fabrication of warm WLEDs with low CCT and superior CRI. Meanwhile, Eu3+-doped Ca2GaNbO6 phosphors with different Eu3+ dopant concentrations were synthesized, and the luminescence of Eu3+ at an optimal concentration of 25 mol% was extensively investigated. Remarkably, Ca2GaNbO6 doped with 25 mol% Eu3+ exhibits a wide excitation band spanning 250–550 nm, with the highest peak observed at 465 nm. This phosphor emits a brilliant red light ranging from 550 to 720 nm. In addition, upon excitation with ultraviolet light at 395 nm, it demonstrates an impressive internal quantum efficiency of 69.24 % and remarkable thermal stability. Furthermore, a white light-emitting diode device with a CCT of 5111 K and Ra value of 88.5 was fabricated. The results suggest that the prepared phosphor, in combination with a near-ultraviolet (NUV) light-emitting diode (LED) chip, has the potential for application in WLEDs. Finally, in the field of anti-counterfeiting technologies, the Ca2GaNbO6: 0.25Eu3+ phosphor emerges as a promising candidate due to its exceptional properties, indicating its good potential for use in anti-counterfeiting inks.

Improved densification of SiCf/SiC composites by microwave-assisted chemical vapor infiltration process based on multifrequency solid-state sources excitation

This paper addresses the possibility of improving and controlling the temperature profile of a Ceramic Matrix Composite preform in a multiport Microwave-assisted Chemical Vapor Infiltration (MW-CVI) pilot-scale plant, based on a multifrequency excitation of the reactor by three solid-state sources. The choice of the most suited excitation frequencies is guided by rigorous numerical modeling of the reactor loaded by the sample, solving the coupled electromagnetic and thermal problems in a self-consistent way. The resulting infiltration front and residual porosity have been evaluated by a pseudo1D model, along the sample thickness, according to the previously computed heating pattern. The practical implementation and validation of the proposed technique are illustrated with MW-CVI trials on 10×10×0.3 cm3 SiCf/(SiC/BN)3/SiC preforms manufactured by Filament Winding method. The obtained results confirm the inside-out densification pattern, expected from the sample volumetric heating, along with an extension of the densification region by a factor of 2–3.

Model-Based PID Tuning Method for a Reactor for Microwave-Assisted Chemistry

This paper presents a model-based PID tuning method for a reactor used in microwave-assisted chemistry. The reactor is equipped with a solid-state source of microwaves and a PID controller capable of increasing or decreasing the delivered microwave power to maintain the reacting substances at the desired temperature. The model has the form of an algorithm applied in numerical simulations of two simultaneous processes: heating a substance by absorbing microwave radiation and cooling it by dissipating heat to the surroundings. It has proven its suitability for tuning the PID controller in a time-efficient manner. Despite some noticeable inaccuracies, the presented approach easily finds PID coefficients that result in stable and repeatable controller operation. In this way, significant time savings can be achieved, as well as minimizing the risks associated with, for example, boiling liquid spills. The article demonstrates that a carefully designed, but still relatively simple, model can yield significant benefits in tuning PID controllers.

Upgrade of DIII-D radial interferometer-polarimeter for large bandwidth, low noise, and toroidal mode number measurements.

Near ion-cyclotron frequency (fci) fluctuations, such as those originating from Global and Compressional Alfvén Eigenmodes (GAEs/CAEs), are expected to be present in future fusion reactors but are not well understood due to the limited availability of core measurements in present-day tokamaks. The measurement bandwidth of the Radial Interferometer-Polarimeter (RIP) diagnostic has been upgraded from 1 to 5MHz to detect these fluctuations in DIII-D. RIP adopts the three-wave technique for simultaneous polarimetric and interferometric measurements. Solid-state microwave sources operating at 650GHz are used as probe beams and provide 5MHz bandwidth for both polarimetric and interferometric measurements. Bandwidths of related hardware, including mixer amplifier, signal cable, and digital phase demodulator, are increased correspondingly. Measurement noise is minimized by reducing the time delay between reference and probe signals to nanosecond level and employing correlation-based techniques. Using the upgraded diagnostic, CAE/GAE-like bursting fluctuations are observed in neutral-beam heated plasmas with toroidal magnetic field Bφ ≈ 1 T. Current upgrades being undertaken would enable the evaluation of toroidal mode number for these modes. This work opens the possibility of better understanding near ion-cyclotron frequency fluctuations in fusion relevant plasmas.

High brightness terahertz quantum cascade laser with near-diffraction-limited Gaussian beam

High-power terahertz (THz) quantum cascade laser, as an emerging THz solid-state radiation source, is attracting attention for numerous applications including medicine, sensing, and communication. However, due to the sub-wavelength confinement of the waveguide structure, direct beam brightness upscaling with device area remains elusive due to several mode competition and external optical lens is normally used to enhance the THz beam brightness. Here, we propose a metallic THz photonic crystal resonator with a phase-engineered design for single mode surface emission over a broad area. The quantum cascade surface-emitting laser is capable of delivering an output peak power over 185 mW with a narrow beam divergence of 4.4° × 4.4° at 3.88 THz. A high beam brightness of 1.6 × 107 W sr−1m−2 with near-diffraction-limited M2 factors of 1.4 in both vertical and lateral directions is achieved from a large device area of 1.6 × 1.6 mm2 without using any optical lenses. The adjustable phase shift between the lattices enables a stable and high-intensity surface emission over a broad device area, which makes it an ideal light extractor for large-scale THz emitters. Our research paves the way to high brightness solid-state THz lasers and facilitates new applications in standoff THz imaging, detection, and diagnosis.

(Invited) Correlation Measurements for Carbon Nanotubes with Quantum Defects

Single-photon sources are one of the essential building blocks for the development of photonic quantum technology. In terms of potential practical application, an on-demand electrically driven quantum-light emitter on a chip is notably crucial for integrating photonic integrated circuits. Here, we propose functionalized single-walled carbon nanotube field-effect transistors as a promising solid-state quantum-light source by demonstrating photon antibunching behavior via electrical excitation. The sp3 quantum defects were formed on the surface of (7, 5) carbon nanotubes by 3,5-dichlorophenyl functionalization, and individual carbon nanotubes were wired to graphene electrode pairs. Filtered electroluminescent defect-state emission at 77 K was coupled into a Hanbury Brown and Twiss experiment setup, and single-photon emission was observed by performing second-order correlation function measurements. We discuss the dependence of the intensity correlation measurement on excitation power and emission wavelength highlighting the challenges of performing such measurements while simultaneously analyzing acquired data. Our results indicate a route toward room-temperature electrically-triggered single-photon emission.

Design of radial interferometer-polarimeter for internal magnetic and density fluctuation measurements at multiple space-time scales in the National Spherical Torus Experiment-Upgrade (NSTX-U).

A Faraday-effect radial interferometer-polarimeter is designed for the National Spherical Torus Experiment-Upgrade (NSTX-U) to measure multiscale magnetic and density fluctuations critical to understanding fusion plasma confinement and stability, including those originating from magnetohydrodynamic instabilities, energetic particle-driven modes, and turbulence. The diagnostic will utilize the three-wave technique with 5MHz bandwidth to simultaneously measure line-integrated magnetic and density fluctuations up to the ion-cyclotron frequency. Probe beams will be launched radially from the low-field side at the NSTX-U midplane, where the measured Faraday fluctuations mainly correspond to radial magnetic fluctuations that directly link to magnetic transport. A correlation technique will be employed to reduce the measurement noise to below 0.01° enabling detection of small amplitude fluctuations. Two toroidally displaced chords with 7° separation will be installed to measure toroidal mode numbers up to n = 25 for mode identification. Solid-state microwave sources operating at 321μm (935GHz) will be used to minimize the impact of the Cotton-Mouton effect.

Reaction pathways for the formation of complex fluorides revealed by in situ synchrotron X-ray diffraction

This study investigated the reaction between LiF, Mo metal, and CuF2 as a solid-state fluorine source to form a complex fluoride, tetragonal trirutile (TR)-type Li2MoF6, in an Ni metal tube by in situ synchrotron X-ray diffraction (SXRD) experiments. As a result, two formation pathways of TR-type Li2MoF6 were identified: one involving a reaction among intermediate phases, i.e., MoF3, and an unknown Mo-containing fluoride, and the starting materials, i.e., LiF, Mo, and CuF2, the other involving a direct reaction between LiF, Mo, and CuF2. The combination of in situ SXRD with differential scanning calorimetry (DSC) revealed that the direct reaction was facilitated by the presence of the liquid phase of LiF-CuF2. Further, the first-order phase transition of Li2MoF6 with a great volume change of 21% was found to occur in the vicinity of 520 °C–550 °C reversibly. Finally, this study demonstrated that an in situ SXRD experiment supported by DSC measurement is a powerful tool for revealing the reaction routes and identifying new phases occurring in sample-loaded metal tubes.

Ni2+ activated broadband near-infrared II germanate phosphor for pc-LED applications

The broadband near-infrared (NIR) pc-LED is considered as a new generation of light source for substance measurements based on NIR spectroscopy. The most studied Cr3+ doped broadband NIR phosphors emit in the near-infrared I region. However, there is a demand for broadband near-infrared II solid-state light sources for expanding the variety of detected substances. Herein, Ni2+ activated NIR II Mg14Ge5O24 phosphor is synthesized by high-temperature solid-state method. The phosphor shows a asymmetric broad NIR emission band peaked at 1420 nm, that is assigned to the 3T2(3F)→3A2(3F) transition of Ni2+. It is observed that the asymmetric emission band is contributed from two Ni2+ centers, Ni2+(I) and Ni2+(II), occupying Ge4+ site with the emission peaked at 1313 nm and Mg2+ site with the emission peaked at 1435 nm, respectively. It is found that the addition of Ti4+ and B3+ can significantly change the intensity ratio of the two Ni2+ centers and enhance the overall emission intensity. Moreover, the addition of Mn4+ results in only Ni2+(II) emission. The origin of the unique features mentioned above is discussed. The temperature dependence of the NIR emissions is also studied. Finally a broadband NIR II pc-LED with a moderate electro-optical conversion efficiency of 1.4 % is fabricated based on a 400 nm LED chip. The results indicate that the modified Mg14Ge5O24:Ni2+ is a potential broadband NIR II phosphor for pc-LED applications.

Quantum emitters in aluminum nitride induced by heavy ion irradiation

The integration of solid-state single-photon sources with foundry-compatible photonic platforms is crucial for practical and scalable quantum photonic applications. This study explores aluminum nitride (AlN) as a material with properties highly suitable for integrated on-chip photonics and the ability to host defect-center related single-photon emitters. We have conducted a comprehensive analysis of the creation of single-photon emitters in AlN, utilizing heavy ion irradiation and thermal annealing techniques. Subsequently, we have performed a detailed analysis of their photophysical properties. Guided by theoretical predictions, we assessed the potential of Zirconium (Zr) ions to create optically addressable spin defects and employed Krypton (Kr) ions as an alternative to target lattice defects without inducing chemical doping effects. With a 532 nm excitation wavelength, we found that single-photon emitters induced by ion irradiation were primarily associated with vacancy-type defects in the AlN lattice for both Zr and Kr ions. The density of these emitters increased with ion fluence, and there was an optimal value that resulted in a high density of emitters with low AlN background fluorescence. Under a shorter excitation wavelength of 405 nm, Zr-irradiated AlN exhibited isolated point-like emitters with fluorescence in the spectral range theoretically predicted for spin-defects. However, similar defects emitting in the same spectral range were also observed in AlN irradiated with Kr ions as well as in as-grown AlN with intrinsic defects. This result is supportive of the earlier theoretical predictions, but at the same time highlights the difficulties in identifying the sought-after quantum emitters with interesting properties related to the incorporation of Zr ions into the AlN lattice by fluorescence alone. The results of this study largely contribute to the field of creating quantum emitters in AlN by ion irradiation and direct future studies emphasizing the need for spatially localized Zr implantation and testing for specific spin properties.

Transdermal Hydrogen Sulfide Delivery Enabled by Open-Metal-Site Metal-Organic Frameworks.

Hydrogen sulfide (H2S) is an endogenously produced gasotransmitter involved in many physiological processes that are integral to proper cellular functioning. Due to its profound anti-inflammatory and antioxidant properties, H2S plays important roles in preventing inflammatory skin disorders and improving wound healing. Transdermal H2S delivery is a therapeutically viable option for the management of such disorders. However, current small-molecule H2S donors are not optimally suited for transdermal delivery and typically generate electrophilic byproducts that may lead to undesired toxicity. Here, we demonstrate that H2S release from metal-organic frameworks (MOFs) bearing coordinatively unsaturated metal centers is a promising alternative for controlled transdermal delivery of H2S. Gas sorption measurements and powder X-ray diffraction (PXRD) studies of 11 MOFs support that the Mg-based framework Mg2(dobdc) (dobdc4- = 2,5-dioxidobenzene-1,4-dicarboxylate) is uniquely well-suited for transdermal H2S delivery due to its strong yet reversible binding of H2S, high capacity (14.7 mmol/g at 1 bar and 25 °C), and lack of toxicity. In addition, Rietveld refinement of synchrotron PXRD data from H2S-dosed Mg2(dobdc) supports that the high H2S capacity of this framework arises due to the presence of three distinct binding sites. Last, we demonstrate that transdermal delivery of H2S from Mg2(dobdc) is sustained over a 24 h period through porcine skin. Not only is this significantly longer than sodium sulfide but this represents the first example of controlled transdermal delivery of pure H2S gas. Overall, H2S-loaded Mg2(dobdc) is an easily accessible, solid-state source of H2S, enabling safe storage and transdermal delivery of this therapeutically relevant gas.

Frequency source design of solid-state microwave source based on phase-locked loop technology

Abstract A high-performance frequency synthesizer based on phase-locked loop (PLL) technology is proposed for high-power, solid-state microwave sources. The PLL circuit is simulated, optimized, and analyzed by using ADIsimPLL software. The methods to improve the phase noise performance of the frequency source are summarized. Using ADF4351, STM32, ADL5611, and other devices to complete the hardware circuit and software control part of the design, the low noise frequency source is successfully established. The frequency source can output the signal in the frequency range of 2.3 G-2.5 G, the phase noise is within - 97.30 dBc@1 KHz, the output power reaches 20 dBm, the overall performance is excellent, and meets the requirements of a solid-state microwave source.