Amplifier System Research Articles

An Optimal Energy Utilization of Cluster Routing Protocol for Wireless Sensor Network in Restricted Area

Objectives: To efficiently monitor the highly confined area by using security measurement methods to enhance the lifetime of a large area coverage network. Methods : the modified nodes are included in the normal execution process of the network to calculate the efficiency and lifetime of the WSN. With the help of the simulation and analysis process, the proposed protocol is found to be more powerful to impact the sustainability of the network by prolonging the lifetime of the nodes. To perform this operation, the following parameters are considered: Area of the monitoring area, Number nodes, Sink portion, Energies of radio amplifier systems, Data aggregation, node electronics, and data packet length. Findings: The proposed optimal energy cluster routing protocol finds the best topological structural protocol to select the cluster head with optimal connectivity path with other nodes in a group. The data of energy utilization, data communication rate between nodes and cluster head, and analysis of the number of alive nodes concerning time are obtained. Novelty: the proposed Optimal efficient cluster routing protocol (OECRP) selects the cluster head by considering energy consumption, cluster sustainability, and its proper communication with other nodes. OECRP is used to develop the optimal topological structural protocol to connectivity path with other nodes in a group. Keywords Heterogeneous network, Low­energy adaptive clustering hierarchy (LEACH), optimal efficient cluster routing protocol (OECRP), Network lifetime, Cluster head selection

Analysis of THz generation using the tilted-pulse-front geometry in the limit of small pulse energies and beam sizes.

Optical rectification in lithium niobate using the tilted-pulse-front geometry is one of the most commonly used techniques for efficient generation of energetic single-cycle THz pulses and the details of this generation scheme are well understood for high pulse energy driving lasers, such as mJ-class, kHz-repetition rate Ti:Sa amplifier systems. However, as modern Yb-based laser systems with ever increasing repetition rate become available, other excitation regimes become relevant. In particular, the use of more moderate pulse energies (in the few µJ to multi-10 µJ regime), available nowadays by laser systems with MHz repetition rates, have never been thoroughly explored. As increasing the repetition rate of THz sources for spectroscopy becomes more relevant in the community, we present a thorough numerical analysis of this regime using a 2+1-D numerical model. Our work allows us to confirm experimental trends observed in this unusual excitation regime and shows that the conversion efficiency is naturally limited by the small pump beam sizes as a consequence of spatial walk-off between the pump and THz beams. Based on our findings, we discuss strategies to overcome the current limitations, which will pave the way for powerful THz sources approaching the watt level with multi-MHz repetition rates.

Ultrafast element-resolved magneto-optics using a fiber-laser-driven extreme ultraviolet light source.

We present a novel setup to measure the transverse magneto-optical Kerr effect in the extreme ultraviolet spectral range based on a fiber laser amplifier system with a repetition rate between 100 and 300 kHz, which we use to measure element-resolved demagnetization dynamics. The setup is equipped with a strong electromagnet and a cryostat, allowing measurements between 10 and 420K using magnetic fields up to 0.86T. The performance of our setup is demonstrated by a set of temperature- and time-dependent magnetization measurements with elemental resolution.

Applying Odor Preconcentrator for Enhancing Human Olfaction: Feasibility Study

Introduction The human sense of smell plays important roles in various scenes in everyday life although we are unconscious of its importance in most cases. For example, olfaction provides alerts that lets us notice dangers or risks such as a fire and rotten food. Savory food smells and comfort flower fragrances make our lives richer. However, it is known that the human olfaction deteriorates with our age [1]. There is no device that can improve the deteriorated olfaction whereas impaired vision can be improved using eyeglasses and a hearing aids can improve our audition. The aim of this research project is to develop an olfactory amplifier for humans [2,3]. In chemical analysis, preconcentrators are frequently used to analyze faint chemical substances [4]. We propose to apply this technique to enhance the sensitivity of human olfaction. In the proposed olfactory amplifier system, airborne odor molecules are collected into adsorbent, as in the preconcentrator. When a sufficient amount of odor molecules are collected, the adsorbent is heated to a high temperature to thermally desorb the collected molecules in a short time. The concentrated odors are thus generated. Here we report our new device made with a monolithic silica adsorbent. Results of an odor concentration experiment and a sensory test are presented to show that the device can generate a clearly perceivable smell from a faint smell sample. Method The schematic diagram of our new device that uses a disc-shaped monolithic silica (MonoTrap DSC18, GL Science) as an adsorbent is shown in Figure 1. The cross section of the device is shown in Figure 2. The diameter and thickness of the monolithic silica disk are 10 mm and 1 mm, respectively. This adsorbent is housed in a flow cell which was made by putting a rubber sheet with a hole in the middle between an acrylic plate and a printed circuit board. A meander heater made on the printed circuit board is used for thermally desorbing the collected odor molecules from the monolithic silica disk. Five stainless-steel tubes are attached to the flow cell. Air is sent into the flow cell through the center tube, and is exhausted from the four outer tubes.In the odor concentration experiment, 1.2 ppm 1-butanol vapor packed in a sampling bag was sent into the flow cell at a flow rate of 0.8 L/min for 10 min. The collected butanol molecules were desorbed by heating up the monolithic silica to 200 degrees centigrade. Clean air was sent to the flow cell at a flow rate of 20 mL/min to take the concentrated odor vapor out from the flow cell. The concentration of the butanol vapor presented from the device was measured using a semiconductor gas sensor (TGS2620, Figaro Engineering). In the sensory test, we prepared liquid apple flavor consisting of nine components. The flavor was diluted by 100 times using liquid paraffin. Eight subjects participated in the sensory test. Each subject was asked to sniff the diluted apple flavor and compare its smell with the smell of the concentrated vapor presented from the odor amplifier device. Results and Discussions Figure 3 shows the response curves of the gas sensor which was exposed to the vapor coming out from the odor amplifier device. The sensor response is defined as the ratio of the sensor resistance in gas to that in air. Its value decreases with the gas concentration. At 20 s from the start of recording the sensor response, the heater was turned on. The pump was activated after 4 s delay from the activation of the heater. The concentration factor calculated from the maximum butanol concentration detected by the gas sensor was 13.1. When the delay was reduced to 0 s, the concentration factor was slightly decreased. Table 1 shows the result of the sensory test. All subjects answered that the vapor presented from the amplifier device had a stronger smell and that the difference in the smell intensity was significant. Seven out of eight subjects even told us that they perceived no smell from the diluted liquid apple flavor. Most subjects told us that the original and concentrated smells were different because they were unable to perceive the original smell. These results show that a sufficient odor amplification effect can be obtained by a concentration factor of approximately 10. Future work will be addressed to enable quicker presentation of concentrated odors. This work was supported in part by JSPS KAKENHI Grant Numbers 19K14947 and 19H02103, and Research Grant from the Okawa Foundation for Information and Telecommunications.

The Impact of Time Delays for Power Hardware-in-the-Loop Investigations

Power hardware-in-the-loop (PHiL) simulations provide a powerful environment in the critical process of testing new components and controllers. In this work, we aim to explain the impact of time delays in a PHiL setup and recommend how to consider them in different investigations. The general concept of PHiL, with its necessary components, is explained and the benefits compared to pure simulation and implemented field tests are presented. An example for a flexible PHiL environment is shown in form of the Power Hardware-in-the-Loop Simulation Laboratory (PHiLsLab) at TU Hamburg. In the PHiLsLab, different hardware components are used as the simulator to provide a grid interface via an amplifier system, a real-time simulator by OPAL-RT, a programmable logic controller by Bachmann, and an M-DUINO microcontroller. Benefits and limitations of the different simulators are shown using case examples of conducted investigations. Essentially, all platforms prove to be appropriate and sufficiently powerful simulators, if the time constants and complexity of the investigated case fit the simulator performance. The communication interfaces used between simulator and amplifier system differ in communication speed and delay; therefore, they have to be considered to determine the level of dynamic interactions between the simulated rest of system and the hardware under test.

IR emission of Er3+ ion-doped fluoroborotellurite glass for communication application

We have successfully synthesized Er3+ ion-doped TeO2-B2O3-ZnF2-BaO using conventional melt and quenching technique to explore their possible future application. The physical properties were determined by their density and molar volume, while the structural properties were observed by FTIR spectra. The optical absorption spectra and emission spectra were measured to study their optical and photoluminescence properties. The optical absorption spectra were measured between 400 to 1800 nm. It shows the hypersensitive transition at 521 nm due to the 4I15/2→2H11/2 transition. The intense emission was shown in the peak of 1541 nm excited by 521 nm due to 4I13/2 to 4I15/ 2 transition. From the analysis of Judd-Ofelt theory, it is found that 1.5 mol% Er2O3 in the glass system possesses JO trendline Ω2 > Ω4 > Ω6 and 2.94 × 10−21 cm2 stimulated emission cross-section with the long radiative lifetime around 12.19 ms. The gain cross-section of prepared glass calculated using the Mc Cumber theory reveals the inversion population of prepared glass at γ≥0.4. It could be concluded from all results that 1.5 mol% Er2O3 doped fluoroborotellurite glass have a high potential for future communication application such as IR optical amplifier, IR laser, and WDM network system in C and L communication band.

Diode-pumped master oscillator power amplifier system based on cryogenically cooled Tm:Y2O3 transparent ceramics

We demonstrated a master oscillator power amplifier system using cryogenically cooled Tm:Y2O3 transparent ceramics. The electro-optically switched master oscillator acted as a seed source and could be tuned from 1 to 100 Hz. A maximum pulse energy of 1.35 mJ with a pulse duration of 30 ns amounting to a peak power of 45 kW was obtained at 10 Hz. The power amplification via double-pass geometry achieved maximum single pulse energy of 2.94 mJ at 10 Hz with a pulse duration of 32 ns. The results showed the pulsed lasing potential of Tm:Y2O3 transparent ceramics at cryogenic temperatures. This gain material can be considered as an alternative gain medium for high average and peak power laser development around 2 µm in nano-second regime.

High-energy nanosecond parametric source at 2.7 µm.

We report a high-energy nanosecond KTiOAsO4-based optical parametric oscillator and amplifier system driven by a 1064-nm, injection-seeded, Q-switched Nd:YAG laser to provide mid-infrared pumping for few-cycle optical parametric chirped-pulse amplification operating in the long-wave infrared spectral regime. An output energy of 10.5 mJ at 2726 nm was obtained from the final power amplifier with a spectral width of 2.8 nm, pulse duration of 1.2 ns, and M2 value of 2.4. The parametric source provides for the second mode of operation, where 10-ns pulses are produced by disabling the electro-optic slicing that enables the 1-ns mode. For 10-ns operation, the source produced energy of 25 mJ with a M2 value of 2.8.

Seeded optical parametric generation in CdSiP2 pumped by a Raman fiber amplifier at 1.24 µm.

We report a seeded optical parametric generator (OPG) producing tunable radiation from 4.2-4.6 µm. The seeded OPG employs a 13 mm long CdSiP2 (CSP) crystal cut for non-critical phase-matching, pumped by a nanosecond-pulsed, MHz repetition rate Raman fiber amplifier system at 1.24 µm. A filtered, continuous-wave fiber supercontinuum source at 1.72 µm is used as the seed. The source generates up to 0.25 W of mid-infrared (MIR) idler power with a total pump conversion of 42% (combined signal and idler).

On-chip sampling of optical fields with attosecond resolution

Time-domain sampling of arbitrary electric fields with sub-cycle resolution enables a complete time-frequency analysis of a system's response to electromagnetic illumination. This provides access to dynamic information that is not provided by absorption spectra alone, and has recently been shown through measurements in the infrared that time-domain optical-field sampling offers significant improvements with regard to molecular sensitivity and limits of detection compared to traditional spectroscopic methods. Despite the many scientific and technological motivations, time-domain, optical-field sampling systems operating in the visible to near-infrared spectral regions are seldom accessible, requiring large driving pulse energies, and large laser amplifier systems, bulky apparatuses, and vacuum environments. Here, we demonstrate an all-on-chip, optoelectronic device capable of sampling arbitrary, low-energy, near-infrared waveforms under ambient conditions. Our solid-state integrated detector uses optical-field-driven electron emission from resonant nanoantennas to achieve petahertz-level switching speeds by generating on-chip attosecond electron bursts. These bursts are used to probe the electric field of weak optical transients. We demonstrated our devices by sampling the electric field of a ~5 fJ, broadband near-infrared ultrafast laser pulse using a ~50 pJ near-infrared driving pulse. Our sampling measurements recovered the weak optical transient as well as localized plasmonic dynamics of the emitting nanoantennas $in~situ$. This field-sampling device--with its compact footprint and low pulse-energy requirements--offers opportunities in a variety of applications, including: broadband time-domain spectroscopy in the molecular fingerprint region, time-domain analysis of nonlinear phenomena, and detailed studies of strong-field light-matter interactions.

Ongoing change in the Australian English amplifier system

ABSTRACT This study takes a corpus-based approach to investigating ongoing change in the Australian English adjective amplifier system based on the Australian component of the International Corpus of English (ICE). The paper analyzes changes in amplifiers across apparent time, with special attention being placed on amplifier–adjective–bigram frequencies, to provide insights into cognitive mechanisms underlying lexical replacement. Specifically, the paper analyzes why the innovative variant really was successful in replacing the traditional amplifier very, while other rivals (e.g. so or pretty) were not. Lexical diversity scores and distinctive collexeme analyses confirm that, in contrast to other rival variants, really specializes on and collocates with a few high-frequency adjectives (HFAs) while being dispreferred by low frequency adjectives. The results of a mixed-effects regression analysis show that the use of really is socially stratified with young speakers preferring really over other variants. In addition, the multivariate analysis shows that the replacement of very by really is a female-dominated change and that the use of really is enhanced by priming. The paper argues that collocating with HFAs leads to deeper entrenchment which, in turn, serves as an advantage in situations where speakers choose between rivalling innovative variants.

Design and performance tests of a modular 166.6-MHz 50-kW compact solid-state power amplifier for the HEPS-TF project

A 166.6-MHz 50-kW power transmitter is required to drive the dressed superconducting radio-frequency (RF) cavity during horizontal tests and to condition the fundamental power couplers as well as higher-order-mode ferrite absorbers. A highly modular yet compact amplifier adopting solid-state technologies was therefore developed in the framework of High Energy Photon Source - Test Facility. All power amplifier and power supply modules are pluggable from the front panel of the amplifier system. A 3-stage power combining topology was realized by using 32 power amplifier modules, 4 eight-way stripline power combiners, 2 two-way 35-kW coaxial power combiners, and 1 two-way 65-kW coaxial power combiner. Each power amplifier module is equipped with individual circulator and load utilizing an optimized cooling circuit design to ensure the entire amplifier system to be operational in both full-transmission and full-reflection scenarios. No final-stage high-power circulator or load is needed. The amplifier system is tunable in pulsed mode for any duty factors and fully functional in the continuous-wave mode as required. Excellent noise suppression and high wall-plug-to-RF efficiency were achieved at nominal power. Comfortable redundancies for both power amplifier and power supply modules were reserved to compensate for any hardware degradations during operations. Temperature, current, voltage, and RF signal of each module as well as cooling were monitored and managed by using EPICS in the control system of the amplifier. An interlock system was also integrated as well as an event logging system for post-mortem analysis. The system has accumulated over 2000 hours of operation. The design and performance tests of the first 166.6-MHz 50-kW modular solid-state power amplifier are presented.

Gain and noise analysis of TDM-pumped fiber Raman amplifier

We report the transmission of signal light and the noise accumulation in the fiber Raman amplifier (FRA) under four-wavelength time-division multiplexing (TDM) pumping. A quality factor that is used to describe the performance of the Raman fiber amplifier system in quantitative analysis is proposed. The results indicate that the power variation of signal light has a certain periodicity that is related to the period of pumping with the TDM pumping. The shorter the pumping period is, the weaker the signal fluctuation is. Through the analysis of noise, it is found that amplified spontaneous emission is the main source of the noise of FRA with TDM-pumping. By comparing the TDM pump scheme with the continuous multiwavelength pump scheme, it is found that the gain of the TDM pump scheme is higher than that of the continuous multiwavelength pump scheme.

10 µJ noise-like pulse generated from all fiberized Tm-doped fiber oscillator and amplifier.

Herein, we presented a high energy noise-like (NL) pulse Tm-doped fiber laser (TDFL) system. Relying on the nonlinear amplifying loop mirror (NALM), stable noise-like pulses with coherence spike width of ∼317 fs and envelope width of ∼4.2 ns were obtained from an all polarization-maintaining fiberized oscillator at central wavelength of ∼1946.4 nm with 3 dB bandwidth of ∼24.9 nm. After the amplification in an all-fiberized TDF amplifier system, the maximum average output power of ∼32.8 W and pulse energy of ∼10.1 µJ were obtained, which represents the highest pulse energy of NL pulse at ∼2 µm, to the best of our knowledge. We believe that the high energy NL pulse source has the potential application in mid-infrared supercontinuum generation.

Iodide/metal-organic frameworks (MOF) -mediated signal amplification strategy for the colorimetric detection of H2O2, Cr2O72− and H2S

The analytical methods based on colorimetric detection of various analytes have attracted intensive interest. However, most of them display relatively low sensitivity. Herein, a novel colorimetric strategy based on iodide/metal-organic frameworks (MOF)-mediated amplification was developed for low-cost, naked-eye detection and quantification of H2O2,Cr2O72−, and H2S. Cu-MOFs could catalyze the oxidation of the colorless peroxidase substrate TMB to produce a blue product. The published researches mainly focused on the immobilization or integration of a macromolecule, such as natural enzymes, to enhance MOFs catalytic abilities. The use of small molecules to improve the catalytic performance of MOFs has rarely reported. Due to the negligible steric hindrance, iodide could easily be adsorbed in the framework pore of MOFs to conduct the synergic catalytic effect, and shows a high catalytic effect. As a result, the catalytic activity of Cu-MOFs was dramatically enhanced, and thus, the nanocatalyst could act as an amplifier system for target detection. The detection limits obtained by the amplified method are 25, 30, and 0.2 nM, respectively, which are about 200-fold lower than that of the unamplified colorimetric assays. The colorimetric strategy developed herein provides a novel system for the detection of low concentrations of analytes in complex biological samples.

Compact millijoule Yb3+:CaF2 laser with 162 fs pulses.

We report on a compact diode-pumped, chirped pulse regenerative amplifier system with a pulse duration of 162 fs and an output pulse energy of 1 mJ before as well as 910 µJ after compression optimized for the probing of ultrafast relativistic laser-plasma processes. A chirped volume Bragg grating (CVBG) acts as a combined pulse stretcher/compressor representing a robust solution for a CPA laser system in the millijoule range. Yb3+:CaF2 is used as gain medium to support a large bandwidth of 16 nm (FWHM) when spectral gain shaping is applied. Chirped mirrors compensate for any additional dispersion introduced to the system.

Holmium-doped fiber amplifier for pumping a ZnGeP2 optical parametric oscillator.

We present a holmium-doped all-fiber master oscillator power amplifier (MOPA) system operating at 2108 nm targeting optical frequency conversion applications. The MOPA delivers pulses of 0.52 mJ energy at 10 kHz repetition rate after three amplification stages, with a close to square-shaped temporal profile of 50 ns duration, diffraction-limited beam quality and linear polarization. Challenges with achieving high gain and efficiency in the final amplification stage are discussed and attributed to quenching effects inferred from measurements of non-saturable absorption in the holmium fibers. Using this MOPA, we demonstrate a mid-IR conversion efficiency of 59% by direct pumping of a ZnGeP2 optical parametric oscillator.

High-power high-beam-quality sealed-off master oscillator – power amplifier system oscillating in the middle infrared spectral range on strontium atomic transitions

High-beam-quality sealed-off master oscillator – power amplifier system is developed and studied based on an atomic strontium vapor laser and delivering high-power laser radiation in the middle infrared spectral range. A diffraction self-filtering of the laser radiation is used to reduce the laser beam divergence to the ultimate diffraction limit. A new optical design is utilized for the master oscillator to visualize the optical path through the entire optical scheme. A large-bore sealed-off laser tube is developed and studied with a stable cavity and is applied as a power amplifier as well. Precise microprocessing of optical grade fused quartz is also performed.

Improved motional Stark effect signal processing using fast Fourier transform spectral analysis.

A Fast Fourier Transform (FFT) based method has been developed, which improves the frequency response of the Motional Stark Effect (MSE) system by about a factor of 10 over the conventional analog lock-in method. The method uses fits to rigorously derived analytic expressions for the FFT spectral components of the MSE signal to accurately obtain the amplitudes and phases of the 2f1 and 2f2 photo-elastic modulator (PEM) frequencies that encode the polarization angle. Since no frequency filtering is used in the FFT method, the frequency response is limited by fundamental measurement properties: the frequency response of the detector, photon statistics, sample rate, and the ability to resolve the spectral components. In contrast, the frequency response of the analog lock-in is limited by a low pass filter with a cutoff of around 500Hz. In the case of the DIII-D MSE system, the output of the photo-multiplier tube detector was sampled at 500 kHz and FFTs with as few as 100 points were used to obtain the amplitudes of the 2f1 and 2f2 PEM frequency components. This corresponds to a frequency response of 5 kHz, about ten times faster than the analog lock-in amplifier system. Details of the FFT method will be presented and compared to those of the analog lock-in system.

High-beam-quality sealed-off master oscillator – power amplifier system oscillating in the visible spectral range on atomic copper transitions for micromachining in research and technology

High-beam-quality sealed-off master oscillator – power amplifier system is developed and studied based on a copper bromide vapor laser and oscillating on atomic copper self-terminating transitions. A detailed study on the laser beam divergence is carried out demonstrating the capability of CuBr vapor laser systems to emit diffraction-limited laser beams. Precise microprocessing of various materials, such as optical grade fused quartz, Si, stainless steel, is also implemented.