Amplifier Module Research Articles

Polarization-isolated stretched-pulse mode-locked swept laser for 10.3-MHz A-line rate optical coherence tomography.

Stretched-pulse mode-locked (SPML) lasing based on a chirped fiber Bragg grating (CFBG) has proven to be a powerful method to generate wavelength-swept lasers at speeds of tens of megahertz. However, light transmitted through the CFBG may lead to undesirable laser oscillation that disrupts the mechanism of the laser active mode locking in the theta ring cavity. In this Letter, we demonstrate a simple and low-cost approach to suppress the transmitted light and achieve an effective duty cycle of ∼100% with only one CFBG and no need for intra-cavity semiconductor optical amplifier (SOA) modulation, extra-cavity optical buffering, and post amplification. By utilizing polarization isolation of the bi-directional CFBG, a swept laser centered at 1305 nm, with repetition rate of 10.3 MHz, optical power of 84 mW, and 3 dB bandwidth of 109 nm, is demonstrated. Ultrahigh speed 3D optical coherence tomography (OCT) structural imaging of a human palm in vivo using this swept laser is also demonstrated. We believe that this ultrahigh speed swept laser will greatly promote the OCT technique for industrial and biomedical applications.

Rapid and Sensitive Human-Specific DNA Quantitation Using a Microfluidic Amplification Module at the Point-of-Care.

A rapid microfluidic human-specific DNA quantitation assay module was developed for chip-based amplification of the human TH01 and Alu loci in the presence of PicoGreen. The method makes use of the thermal cycler and 488 nm Solid State laser-based optical train that are components of the fully-integrated, sample-in to results out, ANDE Rapid Nucleic Acid Analysis system. The assay was effective in quantitating human DNA from a variety of sample types, including blood, buccal, and forensic touch samples mixed with varying amounts of non-human DNA. The 28-cycle TH01 and 10-cycle Alu reactions were completed in 18 minutes and 7 minutes, respectively. The observed limit of detection (LOD) of the assay is approximately 0.3 ng, and the flexibility of assay design allows an LOD of as little as 0.005 femtograms.Clinical Relevance-We have developed a fully-integrated, sample-in to results-out, Rapid Nucleic Acid Analysis system that characterizes nucleic acid fragments (whether generated by PCR, rt-PCR, sequencing, or SNP reactions) by electrophoresis in plastic microfluidic channels. Here we describe the development, characterization, and validation of the microfluidic quantitation module. The quantitation module is the first that can be incorporated into integrated microfluidic workflows for the analysis of highly-multiplexed clinical diagnostic assays interrogating hundreds of genomic targets in a single sample. In particular, the use of a microfluidic quantitation module allows reaction volumes, thermal cycling conditions, and electrophoretic injection protocols to be determined based on nucleic acid content during and throughout fully-automated processing-dramatically enhancing the power of the fully-automated diagnostic system.

A Multi-Contaminants Detection Sensor Based on Digital Lock-In Amplifier Module With High Sensitivity and High Detectability

Wear debris monitoring in lubrication oil has emerged as a promising solution for health monitoring and fault diagnosis of mechanical equipment. However, the debris feature signal is weak and overwhelmed in the noise. Furthermore, the traditional inductive detection sensors suffer from poor detectability to distinguish non-ferromagnetic metal particles. To address these problems, in this paper, a triple-coil inductive debris sensor combined with a digital lock-in amplifier (DLIA) module was proposed to detect and distinguish multiple contaminants in hydraulic oil so as to achieve high sensitivity and high detectability. First, we introduced the sensor design and fabrication. Second, the triple-coil inductive debris sensor model, the DLIA principle, and the performance analysis of suppressing noise for lock-in amplifier were provided, respectively. Finally, both simulation and experimental platforms were built to substantiate the effectiveness of the proposed approach. Experimental results showed that the detection limit of the designed sensor for iron, copper, and aluminium particles could be inferred as 85.4 μm, 102.4 μm, and 111.6 μm, respectively.

Charge Couple Device (CCD) Photoelectric Signal Data Acquisition and Its Application in the Machine Vision of Artificial Intelligence

The development of Charge Couple Device (CCD) technology is particularly rapid in the fields of image sensors and non-contact measurement. In this study, a data acquisition device applied to CCD photoelectric detection system is designed. Among them, the design of the Differential Amplification (DA) module, Analog-to-Digital Converter (ADC) module, First In First Out (FIFO) cache module, and Complex Programmable Logic Device (CPLD) module in this device are emphasized. The ADC circuit in the ADC module converts two 4 MHz analog photoelectric signals generated by the CCD sensor at a frequency of 8 MHz, and then outputs 12-bit digital signals. The collected photoelectric signal is used to detect the damage to the surface of ancient buildings with the machine vision technology of artificial intelligence (AI). In the test, the DA circuit can adjust the voltage range of two photoelectric analog signals output by CCD to a predetermined range (1.5 V∼2.0 V). In the ADC circuit test, there is no data in the FIFO when there is no input conversion, and the converted data will be stored in the internal FIFO during the conversion clock period. Based on machine vision technology, surface damage types of ancient buildings are defined, namely spalling, cracks, and disruption, and surface image samples are generated from collected signals. The samples are trained using the convolutional neural network, and the classifier is generated. The test reveals that the designed photoelectric signal acquisition device and AI machine vision technology can accurately classify the surface damage of ancient buildings.

Modular DNA Tetrahedron Nanomachine-Guided Dual-Responsive Hybridization Chain Reactions for Discernible Bivariate Assay and Cell Imaging.

Engineering of multivariate biosensing and imaging platforms involved in disease plays a vital role in effectively discerning cancer cells from normal cells and facilitating reliable targeted therapy. Multiple biomarkers such as mucin 1 (MUC1) and nucleolin are typically overexpressed in breast cancer cells compared to normal human breast epithelium cells. Motivated by this knowledge, a dual-responsive DNA tetrahedron nanomachine (drDT-NM) is constructed through immobilizing two recognition modules, MUC1 aptamer (MA) and a hairpin H1* encoding nucleolin-specific G-rich AS1411 aptamer, in two separate vertexes of a functional DT architecture tethering two localized pendants (PM and PN). When drDT-NM identifiably binds bivariate MUC1 and nucleolin, two independent hybridization chain reactions (HCRM and HCRN) as amplification modules are initiated with two sets of four functional hairpin reactants. Among them, one hairpin for HCRM is dually ended by fluorescein and quencher BHQ1 to sense MUC1. The responsiveness of nucleolin is executed by operating HCRN utilizing another two hairpins programmed with two pairs of AS1411 splits. In the shared HCRN duplex products, the parent AS1411 aptamers are cooperatively merged and folded into G-quadruplex concatemers to embed Zn-protoporphyrin IX (ZnPPIX/G4) for fluorescence signaling readout, thereby achieving a highly sensitive intracellular assay and discernible cell imaging. The tandem ZnPPIX/G4 unities also act as imaging agents and therapeutic cargos for efficient photodynamic therapy of cancer cells. Based on drDT-NM to guide bispecific HCR amplifiers for adaptive bivariate detection, we present a paradigm of exquisitely integrating modular DNA nanostructures with nonenzymatic nucleic acid amplification, thus creating a versatile biosensing platform as a promising candidate for accurate assay, discernible cell imaging, and targeted therapy.

Reconfigurable all-optical format conversion for 16QAM/8QAM by employing PSA in HNLF.

Extensive investigations are undertaken on the feasibility of utilizing phase sensitive amplification (PSA) in highly nonlinear fiber (HNLF) to achieve a reconfigurable 16QAM/8QAM all-optical format conversion for optical data center networks. A comprehensive theoretical model is developed and subsequently verified, based on numerical simulations undertaken to explore the effectiveness of the nonlinear effects of phase insensitive amplification, PSA, and self phase modulation for the proposed all-optical format conversion scheme. It is demonstrated that the proposed scheme can achieve a reconfigurable all-optical format conversion from a 16QAM signal to two quadrature phase shift keying (QPSK) signals or from an 8QAM signal to one QPSK signal and one binary phase shift keying signal with data rates of 92Gbps and 69Gbps for 16QAM and 8QAM signals, respectively.

Development of an Automated Estimating Electronic Weighing Scale

Analog weighing scales suffer from a lack of precision while reading the output and they can easily be manipulated by any technically biased individual. This paper presents the development of an automated estimating electronic weighing indicator. It aims at developing a means to a framework to evaluate estimated weight in analogue to digital forms, such as to obtain higher precision in estimation and calibration. The circuit consists of a Load Cell, Hx711 Load Cell amplifier, Atmega328 microcontroller, LCD module and a few additional glue components. The 20 kg load cell sends signals of the projected loads to the Hx711 module, which magnifies and sends the corresponding output to the microcontroller. The system uses the 4x3 keyboard to input the unit cost per kg to the electronic scale. The microcontroller automatically adjusts the signals with the load cell amplifier module's guide, thus sending the estimated cost in digital form to the LCD module for display. The circuit was designed, constructed, and tested to show that a computerized electronic weighing system can accurately be calibrated without errors.

High-frequency electric field intensity measurement based on frequency shift with high gain and wide frequency range

For the safe operation of equipment and personal safety protection in high-voltage environments, the precise measurement of the high-frequency electric field is of paramount importance. Optical electric field sensor (OES) is a current research trend for high-frequency electric field measurement but is generally limited by low sensitivity and the need for high-speed acquisition modules. Here, we propose a high-frequency electric field intensity measurement approach based on frequency shift with a high gain and a wide frequency range. We used two different frequency shift methods, i.e., stimulated Brillouin scattering and down-conversion. Based on the former method, an amplification module is designed to enhance the OES signal with a frequency range from 11 GHz to 20 GHz and a noise-suppressed gain of up to 63 dB, and based on the latter one, the high-frequency OES signal is down-converted to a sub-MHz intermediate frequency signal. The frequency shift approach shows the potential to detect and analyze high-frequency electric fields with low cost and a small footprint, which is valuable for their applications in electronic warfare, high-voltage engineering, space exploration, etc.

Study on the Ku band Solid-State Power Amplifier(SSPA) through the 40 W-grade High Power MMIC Development and the Combination of High Power Modules

In this paper, to substitute the existing TWTA(Travailing Wave Tube Amplifier) component in small radar system, we developed the Ku band SSPA(Solid-State Power Amplifier) based on the fabrication of power MMIC (Monolithic Microwave Integrated Circuit) chips. For the development of the 500 W SSPA, the 40 W-grade power MMIC was designed by ADS(Advanced Design System) at Keysight company with UMS GH015 library, and was processed by UMS foundry service. And 70 W main power modules were achieved the 2-way T-junction combiner method by using the 40 W-grade power MMICs. Finally, the 500 W SSPA was fabricated by the wave guide type power divider between the drive power amplifier and power modules, and power combiner with same type between power modules and output port. The electrical properties of this SSPA had 504 W output power, -58.11 dBc spurious, 1.74 °/us phase variation, and -143 dBm/Hz noise level.

Synthesis of Energy Efficiency-Enhanced Directional Modulation Transmitters

this article, we present new approaches to synthesize physical-layer secured directional modulation (DM) transmitters that can improve the overall energy efficiency of the system. This is achieved by creating orthogonal artificial noise (AN) that on one hand preserves signal waveforms only along desired spatial directions, and on the other hand reduces the peak to average power ratio (PAPR) of the transmitted signals. The PAPR-reduced signals become friendly to more efficient power amplifier (PA) modes (of operation), thus improving the energy consumption compared with conventional DM counterparts. In the proposed approach, reduced PAPR is achieved by applying power weighted orthogonal AN on transmitted symbols, so that the average power of signals in the RF chains is elevated, resulting in reduced PAPR. The enhancement of the total power efficiency of the transmitter, and the enhanced secrecy performance evaluated through bit error rate (BER) spatial distributions, are demonstrated through system level numerical simulation studies.

High-directivity and compact microstrip coupler for RF power applications.

A microstrip coupler was designed, fabricated, and tested to monitor the power of the 500MHz kW-level amplifier modules currently installed in an 80-kW solid-state transmitter. The proposed coupler consists of multi-section coupled lines and employs a reverse-coupling scheme, achieving a very compact structure. The dual-side configuration with good termination enables the coupler to have high directivity and wide bandwidth without using any lump components for better temperature stability. Under a low-power test, the measured coupling is 37.69 dB with high directivity from 82 to 700MHz. The coupling is almost independent of the power at 499.65MHz, while the directivity slightly decreases to 33.85 dB at the input power of 1 kW. The maximal insertion loss of 0.08 dB was observed at 1-kW input power. The proposed directional coupler suits many high-power applications, especially in low-frequency regimes.

Compact all-solid-state femtosecond Yb amplifier using a high-brightness multi-watt tapered laser diode

In this work, we present a novel amplification module based on a high-brilliance tapered pump laser diode. A monolithic distributed Bragg grating permits to stabilize the diode wavelength, that was kept at 978.5 nm with a full-width at half-maximum bandwidth <0.2 nm during our experiments. Such a compact and reliable single laser source achieves a maximum output power of about 6.5 W, in a linearly polarized beam with high spatial quality (M2 < 1.5). This allows to optimize the performance of compact amplification modules designed to maximize the gain-per-Watt of absorbed pump power and the optical-to-optical extraction efficiency. To assess the potential of such pump unit, we designed a single-pass and double-pass amplification module based on a 3-mm-long 9.5%-doped Yb:KYW crystal, seeded by a either a cw or a femtosecond oscillator providing a maximum average power of ∼500 mW with output wavelength tunable between 1025 nm and 1035 nm. By tightly focusing the pump beam and carefully optimizing the mode-matching between the almost TEM00 pump and seed beam we achieved a single pass small signal gain G0 > 7 at about 3.5 W absorbed pump power and a maximum output power of 2.2 W, corresponding to an optical-to-optical extraction efficiency close to 50%. The excellent beam quality of the seeder was very well preserved during amplification, resulting in a measured Mx2× My2 <1.1 both in single and double pass.

Linear Voltage Controlled Oscillator Implementation in Electronically Variable Immittances

New realization schemes of electronically tunable inductor (L) and Frequency-Dependent Negative Resistance (D) type immittances using a Current Feedback Amplifier (CFA) and Multiplication Mode Current Conveyor (MMCC) composite active building block (ABB) are proposed. Applications of the immittances to the design of selective filters and LC-type linear voltage controlled quadrature oscillator (LVCQO) are presented. Experimental results based on PSPICE simulation and hardware design for a linear range of oscillation frequency (fo ~ 13.6MHz) with satisfactory phase-noise figure on the oscillator wave response had been verified. Effects of the Active Building Block (ABB)-nodal imperfections are analyzed to be insignificant. The new ideas in this article are two types of immittance functions realizable in the same topology; appropriate frequency-domain selective responses are also presented with experimentation results.

A low-cost and hand-hold PCR microdevice based on water-cooling technology

Polymerase chain reaction (PCR) has become a powerful tool for detecting various diseases due to its high sensitivity and specificity. However, the long thermocycling time and the bulky system have limited the application of PCR devices in Point-of-care testing. Herein, we have proposed an efficient, low-cost, and hand-hold PCR microdevice, mainly including a control module based on water-cooling technology and an amplification module fabricated by 3D printing. The whole device is tiny and can be easily hand-held with a size of about 110mm × 100mm × 40mm and a weight of about 300g at a low cost of about $170.83. Based on the water-cooling technology, the device can efficiently perform 30 thermal cycles within 46min at a heating/cooling rate of 4.0/8.1 ℃/s. To test our instrument, plasmid DNA dilutions were amplified with this device; the results demonstrate successful nucleic acid amplification of the plasmid DNA and exhibit the promise of this device for Point-of-care testing.

Reflection power suppression for solid state amplifiers with combiner optimization.

The application of high-power solid state amplifiers (SSAs) in accelerator facilities is increasing, and equipment failure caused by reflected power is the main risk to their long-term operation. High-power SSAs often comprise multiple power amplifier modules. Full power reflection is more likely to damage the modules in SSAs if the amplitudes of the modules are unequal. Optimization of the power combiners is an effective means for improving the stability of SSAs under high power reflection. This study analyzes the mechanisms and conditions of reflected power generation using the scattering parameters of the combiner and proposes an optimization scheme for the combiner. The simulation and experimental results show that some modules may receive reflected power as high as nearly four times the rated power of one module when the SSA meets certain conditions, which could damage the modules. The maximum reflected power can be effectively reduced and the anti-reflection ability of SSAs can be improved by optimizing the combiner parameters to suppress the maximum reflected power.

Coherent Combining of Phase-Steerable High Power Microwaves Generated by Two X-Band Triaxial Klystron Amplifiers with Pulsed Magnetic Fields

We report the first experimental demonstration of coherent combining of phase-steerable high power microwaves (HPMs) generated by X-band relativistic triaxial klystron amplifier modules under the guidance of pulsed magnetic fields. Electronically agile manipulation of the HPM phase is achieved with a mean discrepancy of 4° at the gain level of 110dB, and the coherent combining efficiency has reached as high as 98.4%, leading to combined radiations with equivalent peak power of 4.3GW and average pulse duration of 112ns. The underlying phase-steering mechanism during the nonlinear beam-wave interaction process is furthermore explored by particle-in-cell simulation and theoretical analysis. This Letter paves the way for high power phase array in large scale and may stimulate new interest in research of phase-steerable high power masers.

Genetic circuits in microbial biosensors for heavy metal detection in soil and water

With the rapid population growth, the world is witnessing an ever-increasing demand for energy and natural resources. Consequently, soil, air, and water are polluted with diverse pollutants, including heavy metals (HM). The detection of heavy metals is necessary to remediate them, which is achieved with biosensors. Initially, these HM were detected using atomic absorption spectroscopy (AAS), emission spectroscopy, mass spectrometry, gas chromatography etc., but these were costly and time consuming which further paved a way for microbe-based biosensors. The development of genetic circuits for microbe-based biosensors has become more popular in recent years for heavy metal detection. In this review, we have especially discussed the various types of genetic circuits such as toggle switches, logic gates, and amplification modules used in these biosensors as they are used to enhance sensitivity and specificity. Genetic circuits also allow for rapid and multiple analyte detection at the same time. The use of microbial biosensors for the detection of HM in the soil as well as the water is also described below. Although with a higher success rate than classical biosensors, these microbial biosensors still have some drawbacks like bioavailability and size of the analyte which are needed to be addressed.

SOA-REAM Assisted Synaptic Receptor for Weighted-Sum Detection of Multiple Inputs

Neuromorphic photonics is a promising research field due to its potential to tackle the limitations arising from the bottleneck of the von-Neumann computation architecture. Inspired by the characteristics and behavior of the biological brain, photonic neural networks are touted as a solution for solving complex problems that require GHz operation at low latency and low power consumption. An essential building block of such a neural network is a low-complexity multiply-accumulate operation, for which efficient functional implementations in the optical domain are sought for. Towards this direction, we present a synaptic receptor that functionally integrates weighting and signal detection. This optical multiply-accumulate operation is accomplished through a monolithic integrated semiconductor optical amplifier and reflective electro-absorption modulator, which together serve as a colorless frequency demodulator and detector of frequency-coded signals. Moreover, we show that two spike trains can be simultaneously processed with alternating signs and detected as a weighted sum. The performance of the proposed synaptic receptors is further validated through a low bit error ratio for signal rates of up to 10 Gb/s.

Bioorthogonal Disassembly of Hierarchical DNAzyme Nanogel for High-Performance Intracellular microRNA Imaging.

Rolling circle amplification (RCA) enables the facile construction of compact and versatile DNA nanoassemblies which are yet rarely explored for intracellular analysis. This is might be ascribed to the uncontrollable and inefficient probe integration/activation. Herein, by encoding with tandem allosteric deoxyribozyme (DNA-cleaving DNAzyme), a multifunctional RCA nanogel was established for realizing the efficient intracellular microRNA imaging via the successive activation of the RCA-disassembly module and signal amplification module. The endogenous microRNA stimulates the precise degradation of DNA nanocarriers, thus leading to the efficient exposure of RCA-entrapped DNAzyme biocatalyst for an amplified readout signal. Our bioorthogonal DNAzyme disassembly strategy achieved the robust analysis of intracellular biomolecules, thus showing more prospects in clinical diagnosis.

Integration studies of RF solid-state generators in the electrical system of NBTF experiments and ITER HNB

SPIDER operation, started in 2018, pointed out performance-limiting issues caused by the technology employed in RF generators, based on tetrode free-running oscillators. One of these limits, namely the onset of frequency instabilities, prevented operation at the full rated power of 200 kW. In addition, tetrodes require high voltage to operate, which translates to risk of flashovers and the necessity to perform conditioning procedures, limiting the overall reliability. These disadvantages, combined with the positive experience gained in the meanwhile on smaller facilities with solid state amplifiers, led to the proposal of a complete re-design of the radiofrequency power supplies. This paper describes the modelling activities used to define specifications and design criteria of the solid-state amplifiers for SPIDER and MITICA, which can be directly transposed to the ITER HNB units when their functionality is proven. We detail the topology of the generators, consisting of class D amplifier modules combined to achieve the required 200 kW, which design is mainly driven by the necessity to deliver nominal power to the ion source, mitigate the risk of obsolescence, and improve the reliability through modularity. Due to the non-standard application, we gave particular focus to the integration of generators in the RF systems of SPIDER and MITICA. Numerical analyses were performed to verify the impact of harmonic distortion on transmission line and RF load components, to address the effect of mutual coupling between RF circuits on the generator output modulation, and to assess the magnitude of common mode currents in the electric system. These studies, as well as the experience gained from SPIDER operation, helped to define dedicated circuit design provisions and control strategies, which are currently being implemented in the detailed design and construction phase of the new RF amplifiers.