Amplifier System Research Articles

Frequency noise suppression of the high-power pumping laser in the SERF atomic magnetometer

Abstract A high-sensitivity SERF atomic magnetometer based on a noise-suppressed master oscillator power amplifier (MOPA) system is demonstrated. The spectrum and frequency noise of the laser are measured and it is proved that the frequency noise in the MOPA system is affected by the amplified spontaneous emission (ASE) stimulated from the power amplifier. The frequency noise of the MOPA system is decreased by filtering out the ASE background in the spectrum through a bandpass filter. The sensitivity of the SERF atomic magnetometer is improved by using the frequency noise-suppressed MOPA system as a pumping laser. This method can also be applied to other precision measurement fields based on the MOPA systems that have high requirement for frequency noise of laser.

High voltage formation using the amplifiers cascading method

The dividing of high voltage broadband non-inverting cascade amplifiers into separate cascades, each of which has independent power sources, is suggested. These cascades are connected to one another in series, switching on the operational amplifiers and the feedback links. The gain of each cascade is determined by the non-inverting scheme of feedback that assures accurate signal processing. To provide stable and effective functioning, the operational amplifiers are supplied with power from transistor repeaters. That assures the required feeding voltage levels. Due to the thorough selection of the gain factor and feeding source voltage, the amplifier system achieves the expended output voltage range.

145 W single-frequency fiber laser at 1607 nm with the seed and MOPA configuration

In this paper, high Er3+ concentration erbium doped fiber (EDF) and erbium-ytterbium co-doped fiber (EYDF) were fabricated for the seed and master oscillator power amplifier (MOPA) system of the single-frequency fiber laser. An in-band pumping source with the wavelength of 1535 nm was proposed to improve the efficiency in the ring-cavity. A slope efficiency of 23.8% with an output power of 49 mW was achieved and the laser linewidth was measured to be 800 Hz. In the MOPA system, a piece of EYDF was used firstly to absorb the backward 1 µm amplified spontaneous emission (ASE) and amplified the signal from the seed. Based on the above methods, an output power of 145 W was achieved at 1607.75 nm. Because of the self-phase modulation, the laser linewidth was expanded to be 10.75 kHz at the output power of 132 W. To the best of our knowledge, this is the highest efficiency and output power of the seed and the highest output power of the 1.6 µm single-frequency fiber laser.

Development of a digital amplifier system for cut-open oocyte electrophysiology

The cut-open oocyte Vaseline gap (COVG) technique is a powerful electrophysiological method for the characterization of ion channels. However, traditional amplifiers for COVG are labor-intensive and require significant user expertise. We introduce an innovative, open-source digital amplifier system with high-speed digitization and software-controlled electronics for computer-driven automation. This system compares well to existing commercial systems in terms of conventional specifications of step response (current peak at 25°μs and decay of 36°μstime constant), current noise (1.0 nA at 3 kHz bandwidth), and dynamic range (96.9 dB). Additionally, it unlocks new methods through close integration of the amplifier and software, including machine learning techniques for tuning capacitive compensation waveforms, achieving a 100-fold suppression of mean-squared transient current, and impedance measurement methods to identify system components such as membrane capacitance and electrode resistances. For future extensions, the design has unique attributes such as real-time digital signal processing for feedback; multiple-input and multiple-output; and allows for user customization. By providing open-source access to the circuit board designs, control software, and FPGA code on GitHub, this approach aims to foster cross-disciplinary collaboration and facilitate instrument customization enabling previously inaccessible electrophysiology experiments.

A study on GaN-based high-efficiency class E power amplifier circuits at medium-low frequencies

Abstract In this paper, a high-power amplifier is designed to address the challenges of low transmission power and poor efficiency in wireless energy transmission technology at low frequencies. The design is based on a class E power amplifier circuit. The theoretical analysis is conducted to determine transistor selection and the static DC operating point. Load traction technology is employed to match the load impedance of the power amplifier, ensuring highly efficient and unified power additional efficiency, and output power. To enhance system stability and feedback compensation, gate series resistance and parallel capacitors are incorporated. Simulation results demonstrate that the designed power amplifier achieves an output power of 48 dBm with a power additive efficiency (PAE) of 85%. Furthermore, the third-order intermodulation component reaches 70 dBm, indicating concentrated output energy and high linearity in the amplifier system. Experimental results validate the consistency between theoretical analysis and model simulation, confirming the stability of the designed power amplifier circuit, and successfully achieving energy-efficient, high-power transmission.

Mid-infrared optical parametric chirped-pulse amplifier at 50 W and 38 fs pumped by a high-power Yb-InnoSlab platform

High-power Yb:InnoSlab lasers are proliferating into multiple modern application areas of laser physics ranging from plasma physics and nanolithography to driving optical parametric amplifiers for high-harmonic generation and attosecond science. Here, we present, the layout, design and first results of an optical parametric chirped-pulse amplifier system pumped by a kW-level average power Yb-InnoSlab laser. We describe the layout and concepts of the pump lasers, with particular attention to the specific design principles required for our application. In the current configuration, the pump laser delivers up to 933 W, 18.7 mJ, 1.2 ps pulses at 50 kHz repetition rate. In a first attempt this has generated above 70 W average power at 2 μm via parametric amplification. Chirped-mirror compression resulted in mJ-level pulses at 50 W and 38-fs pulse duration (5.7 cycles at 2 μm).

An Erbium‐Doped Waveguide Amplifier on Thin Film Lithium Niobate with an Output Power Exceeding 100 mW

AbstractA high‐power thin film lithium niobate (TFLN) erbium‐doped waveguide amplifier (EDWA) is demonstrated with a maximum on‐chip output power of 113 mW and a gain of 16 dB. The on‐chip integrated EDWA is composed of large mode area (LMA) waveguide structures with a total length of 7 cm and a footprint of 1 × 1 cm2. Segmented LMA waveguides are connected with waveguide tapers to achieve on‐chip mode conversion, which maintains single‐mode propagation all over the EDWA even at the waveguide bends. The design leads to a significant increase in the amplified signal power by orders of magnitude and will open an avenue for applications such as on‐chip high‐power lasers and amplifier systems.

A >20-W, linearly polarized single-frequency continuous-wave all-fiber laser at ∼1540 nm

We have developed both theoretically and experimentally an all polarization-maintaining fiber-based master oscillator power amplifier (MOPA) system, which allows for amplifying the single-frequency continuous-wave (CW) fiber laser to >20 W without compromising the laser intensity noise (−110 dBc/Hz@ relaxation oscillation peak) at the specific wavelength of ∼1540 nm. The experimental results agree well with the simulated results. To the best of our knowledge, this is the first demonstration of a ∼1540-nm single-frequency all fiber laser and reaching such a high-power level. The amplified laser features a narrow linewidth of ∼1.4 kHz and a spectral side-mode-suppression ratio of >38 dB, even as the laser wavelength is tuned from 1538.216 nm to 1540.616 nm. It is believed to be the narrowest laser linewidth realized in the <1550-nm wavelength band of an Erbium-Ytterbium co-doped fiber MOPA system. The all polarization-maintaining configuration of the MOPA ensures the amplified laser linearly polarized with the polarization extinction ratio of >22 dB and power root mean square fluctuations of <0.2 %@1h. This high-performance single-frequency fiber laser is expected to be an ideal pump source in the spin-exchange relaxation-free (SERF)-based atomic sensors after second harmonic generation.

Development of a Novel Amplifiable System to Quantify Hydrogen Peroxide in Living Cells.

Although many redox signaling molecules are present at low concentrations, typically ranging from micromolar to submicromolar levels, they often play essential roles in a wide range of biological pathways and disease mechanisms. However, accurately measuring low-abundant analytes has been a significant challenge due to the lack of sensitivity and quantitative capability of existing measurement methods. In this study, we introduced a novel chemically induced amplifiable system for quantifying low-abundance redox signaling molecules in living cells. We utilized H2O2 as a proof-of-concept analyte and developed a probe that quantifies cellular peroxide levels by combining the NanoBiT system with androgen receptor dimerization as a reporting mechanism. Our system demonstrated a highly sensitive response to cellular peroxide changes induced both endogenously and exogenously. Furthermore, the system can be adapted for the quantification of other signaling molecules if provided with suitable probing chemistry.

2.09 µm high-gain, high-energy sub-nanosecond laser amplification system and its application to a millijoule-level mid-infrared ZnGeP2 optical parametric generator.

In this Letter, we report for the first time to our knowledge a 2 mJ-level 2.09 µm Ho:YAG regenerative amplifier (RA) seeded by the first-stage Ho-doped fiber (HDF) preamplifier of a gain-switched laser diode (GSLD). After the single-pass power amplifier (SPPA), the output of a 2.09 µm pulse laser with 1 kHz, 570 ps, and >10 mJ was achieved. The overall gain of the whole amplifier system was greater than 90 dB, providing a novel, stable, and reliable sub-nanosecond (sub-ns) pump source operating at a pulse repetition frequency (PRF) of 1 kHz for an optical parametric generator (OPG) based on ZnGeP2 (ZGP). Specifically, for the ZGP OPG structure, a maximum pulse energy of 1.82 mJ at 3-5 µm had been achieved with an injected pump pulse energy of 5.47 mJ, corresponding to a slope efficiency of 39.5% and an optical-to-optical conversion efficiency (OOCE) of 33.27%.

Biophysical essentials – A full stack open-source software framework for conserved and advanced analysis of patch-clamp recordings

Background and ObjectivesPatch-Clamp recordings allow for in depth electrophysiological characterization of single cells, their general biophysical properties as well as characteristics of voltage- and ligand-gated ionic currents. Different acquisition modes, such as whole-cell patch-clamp recordings in the current or voltage clamp configuration, capacitance measurements or single channel recordings from cultured cells as well as acute brain slices are routinely performed for these purposes. Nevertheless, multipurpose transparent and adaptable software tools to perform reproducible state-of-the-art analysis of multiple experiment types and to manage larger sets of experimental data are currently unavailable. MethodsBiophysical Essentials (BPE) was developed as an open-source full stack python software for transparent and reproducible analysis of electrophysiological recordings. For validation, BPE results were compared with manually analyzed single-cell patch-clamp data acquired from a human in vitro nociceptor-model and mouse dorsal root ganglia neurons. ResultsWhile initially designed to improve time consuming and repetitive analysis steps, BPE was further optimized as a technical software solution for entire workflow processing including data acquisition, data preprocessing, normalization and visualization and of single recordings up to stacked calculations and statistics of multiple experiments. BPE can operate with different file formats from different amplifier systems and producers. An in-process database logs all analysis steps reproducible review and serves as a central storage point for recordings. Statistical testing as well as advanced analysis functions like Boltzmann-fitting and dimensional reduction methods further support the researchers' needs in projects involving electrophysiology techniques. ConclusionsBPE extends beyond available patch-clamp specific, open source – and commercial analysis tools in particular because of reproducible and sharable analysis workflows. BPE enables full analysis from raw data acquisition to publication ready result visualizations – all within one single program. Thereby, BPE significantly enhances transparency in the analytical process of patch-clamp data analysis. BPEs function scope is completely accessible through an easy-to-use graphical user interface eliminating the need for programing language proficiency as required by many community patch-clamp analysis frameworks and algorithms.

In-band pumped, Q-switched thulium-doped fiber laser system delivering 140 W and 7 mJ pulse energy.

We report on a highly efficient, in-band pumped, Q-switched, Tm-doped, rod-type master oscillator power amplifier (MOPA) system delivering up to 140 W average output power and 7 mJ pulse energy with a slope efficiency of 77% at 20 kHz repetition rate. The amplifier is pumped with Raman-shifted fiber lasers centered at 1692 nm. This in-band pump scheme for Tm-doped fiber lasers can significantly mitigate their quantum defect-related heat load limitations. At the same time, this pump wavelength yields a similar amount of storable and extractable energy to the state-of-the-art pumping at 793 nm. This approach has allowed for the development of highly efficient Tm-doped fiber laser systems combining a high average power and a high output pulse energy.

Modeling and analysis of single-mode widely tunable all-fiber Ho-doped CW master oscillator power amplifier system

We report the design of an all-fiber single-mode polarization maintaining widely tunable Ho-doped master oscillator power amplifier (MOPA) system operating in the wavelength range of 2005-2135 nm based on a pre-amplifier and two power amplification stages. The single clad Ho-doped active fibers in the ring cavity based master oscillator, pre-amplifier, and power amplifiers are pumped using 1950 nm semiconductor laser diode pump sources. The amplification of the MOPA system is investigated over the entire spectral range of 2005-2135 nm. The highest output power achieved by the continuous wave (CW) Ho-doped MOPA system is 43 W at a wavelength of 2028.6 nm using pump power of 20 W with power conversion efficiency (PCE) of 90% for second power amplifier while the total pump power of Ho-doped MOPA system is 45 W. Optical bandpass filters (OBPFs) are employed between different stages of MOPA system to enable amplification over the wider spectral range of 2005-2135 nm by suppressing the amplified spontaneous emission (ASE). Not using OBPFs results in amplification that is limited to the spectral range of 2045-2130 nm. Therefore, a penalty of 45 nm can be avoided at the expense of using the OBPFs between different stages of MOPA system. This flexible MOPA system can be used in multiple applications, especially for space-borne high power transmitters operating in atmospheric transmission windows.

Tailoring the visible light band of Watt-level SCs pumped via picosecond pulse with different Raman extent

We investigate the supercontinuum (SC) tailoring property by varying the transmission fiber length after the master oscillator power amplifier system. The conversion efficiency of the visible light band is effectively enhanced via tailoring the Raman extent of the injected 30 ps pulse into the nonlinear photonic crystal fiber (PCF). Experimentally, a 3.6 W all-fiber SC spanning from 414 nm to over 1750 nm (@20 dB) is accomplished by using a high duty cycle domestic PCF through precisely controlling the extent of Raman effect. The proposed method is instructive for the further realization of high power SC with an enhanced spectral intensity in the visible light band.

Design and Development of Line Following Tour Guide Robot

The aim of this research project is to develop a Tour Guide Robot showing sufficient intelligence to work as a tourguide in different environments. In doing so, both a software and a hardware architecture are proposed, the different modules of which, such as a sensor, speaker, amplifier, motor(dc), and display, among others, control the different components of the robot. Those components are in turn used by other modules designed for navigation and interaction. A sensor fusion for the purposes of localization is implemented by means of an Arduino Uno Board, which is one of the control module components, together with the other sensors needed for path following. A speaker and amplifier system that controls the voice modules also forms part of this architecture for assisting interaction. Finally, all the modules are controlled with an Arduino Uno Board and programming language. The modules are optimized for immediate execution to achieve navigation and human–machine interaction. The interaction with visitors will be achieve through video display on an android tablet placed on top of the robot. The tour guide robot will display the video about the place it visits when the visitors press the video play button on the android tablet screen.

High-power and high-speed all-optical all-fiber wavelength-swept source at 2 μm based on a femtosecond laser and time stretch technique

We present an all-fiber all-optical high-speed wavelength-swept laser source at 2 μm with a 3-dB bandwidth of 33 nm and repetition rate of 18.4 MHz, by using optical time-stretch technology, which to our knowledge is the first report of a 2 μm wavelength-swept source without any bulk, free-space optical elements. The light source is built upon a nonlinear polarization rotation mode-locked femtosecond oscillator. A chirped fiber Bragg grating (CFBG) is employed to realize the all-optical wavelength sweeping. In comparison with the commonly used dispersive fibers, the CFBG possesses outstanding power efficiency and temporal stability, especially for wavelength sweeping in the 2.0 μm wavelength regime. A two-stage fiber amplifier system is utilized to boost the output power up to 1.01 W. This all-fiberized mode-locked swept source with high speed and high stability shows great potential as a valuable source for various spectroscopy applications and swept source optical coherence tomography, particularly for highly scattering medium with low water content.

A 71 mJ, 300 Hz mid-infrared source based on ZnGeP2 MOPA system

We demonstrated a 71 mJ mid-infrared ZnGeP2 (ZGP) master oscillator power amplifier (MOPA) system that operated at the pulse repetition frequency of 300 Hz. A 2090.6 nm electro-optical Q-switched holmium:yttrium–aluminum-garnet MOPA system with a total energy of 138.3 mJ was used as the pump source of the ZGP-MOPA system. First, based on a ZGP optical parametric oscillator, a mid-infrared laser output of 1.3 mJ was obtained in the state of low-energy pumping. The corresponding beam quality factor M2 was 2.01 × 2.10 (horizontal directions × vertical directions). After two-stage amplification, a mid-infrared laser of 71 mJ was obtained. The pump energy and seed energy of the second ZGP optical parametric amplifier were 92.7 mJ and 23 mJ, the corresponding slope efficiency was 70.3 %. At the maximum output energy level, the pulse width of the mid-infrared laser was 14.6 ns, and the beam quality factor M2 was 3.96 × 3.75.

A corpus‐based analysis of adjective amplification in Hong Kong, Indian and Philippine English

AbstractThis study considers a corpus‐based approach for analysing adjective amplifier systems (very, really, so, etc.) in Hong Kong English (HKE), Indian Englsih (IndE) and Philippine English (PhiE) based on data from the International Corpus of English. The current study adds to existing research by providing insights into the understudied adjective amplifier systems of Asian Englishes. The study describes the amplifier systems in HKE, IndE and PhiE, and it ascertains if these amplifier systems are undergoing change. In the latter context, the analysis assesses if really or so is replacing very as the dominant adjective amplifier in these varieties—a trend shown to be at work in Inner Circle varieties of English. The results of Conditional Inference Trees show that the amplifier systems of HKE and IndE are very stable and amplifier choice in these varieties is determined predominately by intra‐linguistics factors (adjective type, syntactic context and semantic category). In contrast, the amplifier system of PhiE shows notable signs of ongoing change, which is driven predominately by social factors (age and gender of speakers). The results indicate that during stasis and initial stages of change, language‐internal factors determine amplifier choice, while social factors become more important once changes have reached the midrange. The paper argues that once certain variants (really and so) gain social meaning, it is this social meaning (the association with specific social groups) that drives and accelerates change as speakers want to associate with social groups that carry covert prestige.

Single-frequency high-energy pulses from an Er:Yb glass planar waveguide amplifier with good beam quality

We demonstrate a master oscillator power amplifier system that emits single-frequency, high-energy optical pulses at 1539 nm using an Er, Yb:glass planar waveguide amplifier with a normalized frequency of the waveguide of 4.4. A maximum pulse energy of 9.7 mJ is observed at a repetition frequency of 500 Hz. The signal to noise ratio is 25 dB and is independent of the repetition frequency from 100 to 500 Hz. The beam quality factor M2 of the output is 1.03 thanks to the small normalized frequency of the planar waveguide.

Energy Amplifier Systems as Sustainable Nuclear Reactors: An Overview

One of the present major issues for industrialised societies is the environmental impact of energy production. Nuclear power is identified as a possible sustainable opportunity to provide a technological answer to this problem. This review aims to overview the physical bases of accelerator-driven systems, focusing on spallation and transmutation phenomena. A discussion on the possible use of these nuclear devices is developed in the context of sustainable energy production, showing a possible new approach to nuclear energy, based on the developments of accelerator physics and technology during the last century.