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Showing papers on "Amplifier published in 2022"


Journal ArticleDOI
05 Apr 2022-Science
TL;DR: Kim et al. as discussed by the authors demonstrated a photonic integrated circuit-based erbium-doped optical amplifier reaching 145 milliwatts of output power and more than 30 decibels of small-signal gain.
Abstract: Erbium-doped fiber amplifiers revolutionized long-haul optical communications and laser technology. Erbium ions could provide a basis for efficient optical amplification in photonic integrated circuits but their use remains impractical as a result of insufficient output power. We demonstrate a photonic integrated circuit–based erbium amplifier reaching 145 milliwatts of output power and more than 30 decibels of small-signal gain—on par with commercial fiber amplifiers and surpassing state-of-the-art III-V heterogeneously integrated semiconductor amplifiers. We apply ion implantation to ultralow–loss silicon nitride (Si3N4) photonic integrated circuits, which are able to increase the soliton microcomb output power by 100 times, achieving power requirements for low-noise photonic microwave generation and wavelength-division multiplexing optical communications. Endowing Si3N4 photonic integrated circuits with gain enables the miniaturization of various fiber-based devices such as high–pulse-energy femtosecond mode-locked lasers. Description On-chip optical amplification The success of long-haul optical communications and our information society is largely due to the invention of the erbium-doped fiber amplifier. Because the need for faster chips is expected to see a shift from electronics- to photonics-based technologies, erbium ions could form the basis for amplification in optical integrated circuits. Liu et al. used an ultra-low-loss silicon nitride photonic integrated circuit with a waveguide length up to 0.5 meters and erbium ion implantation to fabricate an erbium-doped waveguide amplifier on a compact photonic chip (see the Perspective by Kim). Operating in the continuous-wave regime and providing large optical gain in the telecommunication bands, the results are promising for device applications. —ISO An erbium-doped optical amplifier is fabricated on a silicon-nitride-based optical platform.

55 citations


Journal ArticleDOI
TL;DR: In this article , the authors proposed a sub-connected architecture of active RIS, where multiple elements control their phase shifts independently but share a same power amplifier, which significantly reduces the number of power amplifiers for power saving at the cost of fewer degrees of freedom (DoFs) for beamforming design.
Abstract: To overcome the “multiplicative fading effect” introduced by passive reconfigurable intelligent surface (RIS), the concept of active RIS has been recently proposed to amplify the radiated signals. However, the existing fully-connected architecture of active RIS consumes high power due to the additionally integrated active components. To address this issue, we propose the sub-connected architecture of active RIS. Different from fully-connected architecture, where each element integrates a dedicated power amplifier, in the sub-connected architecture, multiple elements control their phase shifts independently but share a same power amplifier, which significantly reduces the number of power amplifiers for power saving at the cost of fewer degrees of freedom (DoFs) for beamforming design. Fortunately, our analysis reveals that performance loss introduced by the sub-connected architecture is slight, indicating that it can achieve much higher energy efficiency (EE). Furthermore, we formulate the EE maximization problem in the active RIS-aided system for both architectures and develop a corresponding joint beamforming design. Simulation results verify the proposed sub-connected architecture as an energy-efficient realization of active RIS.

40 citations


Journal ArticleDOI
TL;DR: In this article , the effective role of optical duobinary transmitter with optical coherent quadrature amplitude modulation (QAM) receiver based on light amplifiers measured is stimulated by using optisystem simulation software version 13.
Abstract: Abstract Effective role of optical duobinary transmitter with optical coherent quadrature amplitude modulation (QAM) receiver based on light amplifiers measured is stimulated by using optisystem simulation software version 13. Signal, noise power levels are stimulated after long haul fiber optic range up to 350 km distance. Measured light amplifiers, optical duobinary transmitters and optical QAM receiver are employed to measure the peak signal amplitude power (SAP) and noise signal power for bit rate transmission with 100 Gb/s based 350 km length. Maximum signal power level margin is enhanced with high data rates transmission.

35 citations


Journal ArticleDOI
TL;DR: In this paper , a dual-mode configurable and tunable power amplifier (PA) that achieves a widebandwidth and high gain across a operational frequency spectrum of 20 to 30 GHz is presented.

33 citations


Journal ArticleDOI
25 Nov 2022-Sensors
TL;DR: In this paper , an approach has been developed for optimizing AISQ characteristics according to the criterion of minimum loss when amplifying modern telecommunication signals with Rayleigh envelope distribution, and the optimal quantization levels are determined and the energy characteristics of AisQ are calculated.
Abstract: Increasing the efficiency of transmitters, as the largest consumers of energy, is relevant for any wireless communication devices. For higher efficiency, a number of methods are used, including envelope tracking and envelope elimination and restoration. Increasing the bandwidth of used frequencies requires expanding envelope modulators bandwidth up to 250–500 MHz or more. The possibility of using amplifiers with input signal quantization (AISQ), as an alternative to the most common hybrid envelope tracking modulators, is considered. An approach has been developed for optimizing AISQ characteristics according to the criterion of minimum loss when amplifying modern telecommunication signals with Rayleigh envelope distribution. The optimal quantization levels are determined and the energy characteristics of AISQ are calculated. AISQ loss power is shown to decrease by 1.66 times with two-level quantization, by 2.4 times with three-level quantization, and by a factor of 3.0–3.7 for four–five quantization levels compared to a class B amplifier. With these parameters, AISQ becomes competitive with respect to hybrid envelope tracking modulators but does not have electromagnetic interference from the pulse width modulation (PWM) path.

32 citations


Journal ArticleDOI
TL;DR: In this paper , a channel reconstruction method (CRM) is proposed to reconstruct a virtual copy of an actual transmission channel in the digital domain, where optical fibers and amplifiers are modeled as the split-step Fourier method for the Manakov equation while optical filters are emulated as complex-valued finite impulse response filters.
Abstract: Optical transmission links are generally composed of optical fibers, optical amplifiers, and optical filters. In this paper, we present a channel reconstruction method (CRM) that extracts physical characteristics of multiple link components such as longitudinal fiber losses, chromatic dispersion (CD), multiple amplifiers’ gain spectra, and multiple filters’ responses, only from receiver-side (Rx) digital signal processing (DSP) of data-carrying signals. The concept is to reconstruct a virtual copy of an actual transmission channel in the digital domain, where optical fibers and amplifiers are modeled as the split-step Fourier method for the Manakov equation while optical filters are emulated as complex-valued finite impulse response filters. We estimate the model parameters such as losses, CD, gains, and filter responses from boundary conditions, i.e., transmitted and received signals. Experimental results show that, unlike traditional analog testing devices such as optical time-domain reflectometers and optical spectrum analyzers, CRM visualizes multi-span characteristics of fibers, amplifiers, and filters in Rx DSP, and thus localizes anomaly components among multiple ones without direct measurement.

28 citations


Journal ArticleDOI
TL;DR: In this paper , the authors proposed a composite microstrip/coplanar waveguide line (CM/CPW line) to achieve circuit miniaturization by consolidating microstrip lines (MLs) and coplanar Waveguide (CPW) lines on a single dielectric substrate.
Abstract: The rapid development of modern communication systems propels the demand of high performance and miniaturization of RF/microwave components. Power dividers and filters are indispensable circuit components in amplifiers and antenna feed-networks which occupy large footprint of circuit broads, particularly at low frequency. The purpose of this study is to initiate a new type of planar transmission line with unique dual signal-path characteristics and ultimately achieve circuit miniaturization. In this paper, a novel technique of consolidating microstrip lines (MLs) and coplanar waveguide (CPW) lines on a single dielectric substrate, designated as the composite microstrip/CPW line (CM/CPW line), is proposed. With reference to the average line length of ML and CPW, it warrants a physical length reduction of 48.3% and further achieves a reduction of 80.8% after zigzagging CM/CPW line. The proof-of-concept design example of a two-way Wilkinson power divider (WPD) has demonstrated the effectiveness of the miniaturization technique. The simulation, in combination with the experimental results, validates that a size reduction factor of 86.9% when compared to conventional one has been achieved while maintaining a fractional bandwidth of 57.7% for the WPD.

26 citations


Journal ArticleDOI
TL;DR: In this paper , a real-valued time-delay convolutional NN (RVTDCNN) was proposed for wideband power amplifier (PA) models, where the input data of the model is sorted and arranged as a graph composed of the in-phase and quadrature components and envelope-dependent terms of current and past signals.
Abstract: Power amplifier (PA) models, such as the neural network (NN) models and the multilayer NN models, have problems with high complexity. In this article, we first propose a novel behavior model for wideband PAs, using a real-valued time-delay convolutional NN (RVTDCNN). The input data of the model is sorted and arranged as a graph composed of the in-phase and quadrature ( $I/Q$ ) components and envelope-dependent terms of current and past signals. Then, we created a predesigned filter using the convolutional layer to extract the basis functions required for the PA forward or reverse modeling. Finally, the generated rich basis functions are input into a simple, fully connected layer to build the model. Due to the weight sharing characteristics of the convolutional model’s structure, the strong memory effect does not lead to a significant increase in the complexity of the model. Meanwhile, the extraction effect of the predesigned filter also reduces the training complexity of the model. The experimental results show that the performance of the RVTDCNN model is almost the same as the NN models and the multilayer NN models. Meanwhile, compared with the abovementioned models, the coefficient number and computational complexity of the RVTDCNN model are significantly reduced. This advantage is noticeable when the memory effects of the PA are increased by using wider signal bandwidths.

26 citations


Journal ArticleDOI
TL;DR: In this article , the suitability of different amplifier technologies for signal amplification in different wavelength bands is investigated for short-term and mid-term implementation, and the availability of qualified components, notably the required pump laser diodes, is considered.
Abstract: Opening new wavelength bands is the most economic step for further increasing the capacity of optical transmission links. Characteristics of different amplifier technologies for signal amplification in different wavelength bands are detailed. In particular, the suitability of these technologies for short–term and mid–term implementation is considered. An important criterion is the availability of qualified components, notably the required pump laser diodes. On this basis, solutions for the near–term and the mid–term are discussed.

24 citations


Journal ArticleDOI
TL;DR: In this paper , the authors proposed negative stiffness inertial-amplifier-base-isolators to achieve enhanced broadband vibration control by tuning a single system parameter, namely the mass tuning ratio for novel isolators.

24 citations


Journal ArticleDOI
06 Mar 2022
TL;DR: In this article , the authors focus on realizing high-energy solid-state disk and slab systems and the nonlinear suppression strategies for high-power fiber systems using the functional fibers.
Abstract: High‐power laser sources are widely used in industrial precision processing and act as a new platform for strong‐field physics research using peak power over petawatt. This review focuses on realizing high‐energy solid‐state disk and slab systems and the nonlinear‐suppression strategies for high‐power fiber systems using the functional fibers. First, the implementations and enabling technologies of the solid‐state lasers for increasing peak power from gigawatt to petawatt are reviewed. Then the mechanisms and suppression strategies of the deterioration effects (including stimulated Raman scattering, stimulated Brillouin scattering, and transverse mode instability) in various fiber amplifiers are analyzed. At the same time, the mechanism and achievements of the current functional fibers are introduced. Finally, the challenges and perspectives of high‐power solid‐state and fiber amplifiers are summarized.

Journal ArticleDOI
TL;DR: In this article , an erbium-doped fiber amplifier (EDFA) with an operating frequency band targeting an NH3 absorption line falling at 1531.68 nm and capable to emit up to 3 W of optical power was employed.

Journal ArticleDOI
TL;DR: In this article , a G-band gyrotron traveling-wave tube (gyro-TWT) amplifier is presented, which is operated in a circular TE01 mode at the fundamental cyclotron harmonics, driven by a 50kV, 3-A gyrating electron beam.
Abstract: Overall design and cold test of a G-band gyrotron traveling-wave tube (gyro-TWT) amplifier are presented. This gyro-TWT aims at achieving a goal of 10-kW pulse output power in the range of 210–220 GHz. It is operated in a circular TE01 mode at the fundamental cyclotron harmonics, which is driven by a 50-kV, 3-A gyrating electron beam. Low velocity spread diode-type magnetron injection gun (MIG), multichannel TE01 mode input coupler, broadband metasurface output window, and lossy material loaded beam–wave interaction circuit are simulated and partially measured. Particle-in-cell (PIC) simulation shows that the designed gyro-TWT can achieve a saturated output power over 10 kW in the range of 210–228 GHz with a beam velocity spread of 2.29%.

Proceedings ArticleDOI
01 Mar 2022
TL;DR: This work compares S+C+L link power optimization based on the fast and simple heuristic balance of linear and nonlinear noises versus more complex ML-based techniques to estimate optimum per-band line amplifier settings for system capacity maximization.
Abstract: We compare S+C+L link power optimization based on the fast and simple heuristic balance of linear and nonlinear noises versus more complex ML-based techniques to estimate optimum per-band line amplifier settings for system capacity maximization. © 2021 The Author(s)

Journal ArticleDOI
TL;DR: In this article, a top-illuminated avalanche photodiode (APD) was proposed to circumvent the problem of serious bandwidth degradation under high gain (>100) and high power operation and significantly enhance the dynamic range in the established frequency modulated continuous wave (FMCW) lidar system.
Abstract: In this work, we demonstrate a novel In0.52Al0.48As based top-illuminated avalanche photodiode (APD), designed to circumvent the problem of serious bandwidth degradation under high gain (>100) and high power operation and significantly enhance the dynamic range in the established frequency modulated continuous wave (FMCW) lidar system. In our APD design, the carriers transiting through the dual multiplication (M-)layers are subjected to a stepped-up electric field profile, so they can be energized by the first step and propagate to the second step to trigger the avalanche processes. Such a cascade avalanche process leads to an ultra-high gain bandwidth product (460 GHz) with a 1 A/W responsivity at unit gain. Compared to the high-performance and commercial p-i-n PD and photo-receiver (PD + trans-impedance amplifier (TIA)) installed in the same lidar test bed, our demonstrated APD receiver (without TIA) has a larger S/N ratio under high operation gain (33 A/W) with less optical local-oscillator (LO) power required (0.25 vs. 0.5 mW), while exhibiting a wider dynamic range in each pixel. These advantages in turn lead to the construction of a better quality of 3-D lidar image by using the demonstrated APD.

Journal ArticleDOI
TL;DR: The proposed framework nucleic acid-based nonenzymatic spatial-confinement amplifier for rapid and reliable intracellular miRNA imaging can enable accurate and effective monitoring of miRNA expression levels in living cells and poses great potential in medical diagnostics and biomedical research.
Abstract: Real-time in situ monitoring of miRNAs in living cells is often appealed to signal amplifiers to tackle their low abundance challenges. However, the poor kinetics of amplifiers and potential interferences from the complex intracellular environment hamper its widespread applications in vivo. Herein, we report a framework nucleic acid (FNA)-based nonenzymatic spatial-confinement amplifier for rapid and reliable intracellular miRNA imaging. The amplifier consists of a localized catalytic hairpin assembly (L-CHA) reactor encapsulated in the inner cavity of an FNA (a 20 bp cube). The L-CHA reactor is certainly confined to the internal frame by integrating two probes (H1 and H2) of the L-CHA within a DNA strand and harnessing it to the opposite angles of the cube. We find that the stability of the amplifier is remarkably improved due to the protection of the FNA. More importantly, the spatial-confinement effect of the FNA can endow the confined L-CHA amplifier with enhanced local concentrations of reagents (5000-fold), thereby accelerating the reaction rate and improving the dynamic performance (up to 14.34-fold). With these advantages, the proposed amplifier can enable accurate and effective monitoring of miRNA expression levels in living cells and poses great potential in medical diagnostics and biomedical research.

Proceedings ArticleDOI
15 Mar 2022
TL;DR: In this paper , a theoretical approach to calculate reverse intermodulation distortion (RIMD) in voltage mode Class D (VMCD) RF power amplifiers has been developed.
Abstract: The development of 5G technologies, Multiple-Input Multiple-Output (MIMO) systems and Internet of Things (IoT) leads to change in the traditional paradigm of frequency-territorial planning. Indeed, in addition to reducing the distance between base stations of cellular communication, there is a problem of come close to them by radio means of mobile devices. In these cases, reverse intermodulation distortion (RIMD) occurs between closely spaced simultaneously operating transmitters. If they fall into the reception band, they disrupt the normal functioning of radio equipment. Therefore, the requirements for transmitters EMC characteristics are increasing. Class D power amplifiers in addition to higher efficiency, potentially, may have lower RIMD. The article discusses RIMD in previously unexplored Voltage Mode Class D (VMCD) RF Power Amplifiers. The theoretical approach to calculating RIMD in VMCD RF power amplifiers has been developed. The analysis performed showed that in order to achieve the desired levels of intermodulation distortion, not exceeding -70 dB, it is necessary to ensure the difference in saturation resistances is not more than 20% and saturation time deviation from the meander is not more than 2 degrees.

Journal ArticleDOI
TL;DR: In this article , a low-noise low-voltage neural recording amplifier suitable for amplifying local field potentials and extracellular action potentials has been proposed to meet the end requirement of implantable neuro-medical system.
Abstract: Design of amplifier circuits with low-noise operable at low-power to be used, especially for implantable neural interfaces, remains a huge challenge. This research paper presents the design of a low-noise low-voltage neural recording amplifier suitable for amplifying local field potentials and extracellular action potentials so as to meet the end requirement of an implantable neuro-medical system. Critical performance parameters of the smaller circuit blocks of the complete neural amplifier architecture have been found with the help of detailed mathematical analysis and then verified by the simulations conducted using 0.18 µm 4M1P foundry Semi-conductor Laboratory N-well process. The neural amplifier design proposed in this paper passes neural signal of interest with a mid-band gain of 49.9 dB over a bandwidth of 5.3 Hz-8.6 kHz, draws only 11.5 µW of power from ±0.9 V supply voltage, and exhibits an input-referred noise of 2.6 µVrms with a noise efficiency factor of 2.27. The area consumed by the proposed neural amplifier architecture is 0.192 mm2. The complete circuit design carried out in this paper should prove to be useful in equipment for the diagnosis of neurological disorders.

Journal ArticleDOI
TL;DR: In this paper , weakly nonlinear kinetic inductance intrinsic to a superconducting film of niobium titanium nitride was used to construct a microwave parametric amplifier with high phase-sensitive gain and high power handling.
Abstract: Microwave parametric amplifiers operating at the quantum noise limit have become indispensable tools for a range of cryogenic quantum technologies. These amplifiers are typically constructed from nonlinear Josephson junctions, which limit the ability to amplify high-power signals. This study reports a device based instead on the weakly nonlinear kinetic inductance intrinsic to a superconducting film of niobium titanium nitride. The amplifier offers large phase-sensitive gain and high power handling, plus a simple design and fabrication process. As it contains no junctions, it is robust to electrostatic discharge and potentially operable under high temperatures and large magnetic fields.

Journal ArticleDOI
TL;DR: In this article , the impact of signal bandwidth on the TMI threshold of fiber amplifiers has been investigated and the experimental results reveal that the threshold grows, keeps constant, and further grows as a function of spectral linewidth of seed lasers.
Abstract: In this work, we conduct a detailed experimental study on the impact of signal bandwidth on the TMI threshold of fiber amplifiers. Both the filtered superfluorescent fiber sources and the phase-modulated single-frequency lasers are employed to construct seed lasers with different 3 dB spectral linewidths ranging from 0.19 nm to 7.97 nm. The TMI threshold of the fiber amplifier employing those seed lasers are estimated through the intensity evolution of the signal laser, and different criteria have been utilized to characterize the spectral linewidth of the seed lasers. Notably, the experimental results reveal that the TMI threshold of fiber amplifiers grows, keeps constant, and further grows as a function of spectral linewidth of seed lasers. Our experimental results could provide a well reference to understand the mechanism of the TMI effect and optimize the TMI effect in high-power fiber amplifiers.

Journal ArticleDOI
TL;DR: In this article , the authors demonstrate broadband entanglement generation between two modes separated by up to 400 MHz by measuring logarithmic negativity between 0.27 and 0.51 and collective quadrature squeezing below the vacuum limit.
Abstract: Traveling wave parametric amplifiers (TWPAs) have recently emerged as essential tools for broadband near quantum-limited amplification. However, their use to generate microwave quantum states still misses an experimental demonstration. In this Letter, we report operation of a TWPA as a source of two-mode squeezed microwave radiation. We demonstrate broadband entanglement generation between two modes separated by up to 400 MHz by measuring logarithmic negativity between 0.27 and 0.51 and collective quadrature squeezing below the vacuum limit between 1.5 and 2.1 dB. This work opens interesting perspectives for the exploration of novel microwave photonics experiments with possible applications in quantum sensing and continuous variable quantum computing.

Journal ArticleDOI
TL;DR: In this paper , a Doherty power amplifier using a three-port harmonic injection network (HIN) to extend its high-efficiency range is proposed, where the optimal drain fundamental frequency termination for the carrier device at backoff and saturation can be realized simultaneously thus enhancing the efficiency at back-off significantly.
Abstract: In this paper, a Doherty power amplifier (DPA) using a novel three-port harmonic injection network (HIN) to extend its high-efficiency range is proposed. With the help of a part of the three-port HIN, which is placed between the carrier and peaking branches, the optimal drain fundamental frequency termination for the carrier device at back-off and saturation can be realized simultaneously thus enhancing the efficiency at back-off significantly. Meanwhile, this three-port HIN can also realize second harmonic drain terminations for the carrier and peaking device with the quasi-open and quasi-short circuit at the current plane, respectively. Consequently, the saturated power ratio between peaking and carrier devices is increased, which further extends the back-off range of the asymmetric drain-biased DPA. For demonstration purposes, an extended high efficiency range DPA was designed and fabricated using commercially available GaN HEMT (Cree CGH 40010F) devices. Measured results for this novel idea gave drain efficiencies better than 62.5% at 9-9.5 dB back-off point from 1.60 to 1.95 GHz.

Journal ArticleDOI
TL;DR: This work presents a light-tolerant and low-power neural recording IC for motor prediction that can fully function in up to 300 $\mu \text{W}$ /mm2 of light exposure and achieves the best-in-class power consumption.
Abstract: Miniaturized and wireless near-infrared (NIR)-based neural recorders with optical powering and data telemetry have been introduced as a promising approach for safe long-term monitoring with the smallest physical dimension among state-of-the-art standalone recorders. However, the main challenge for the NIR-based neural recording integrated circuits (ICs) is to maintain robust operation in the presence of light-induced parasitic short-circuit current from junction diodes. This is especially true when the signal currents are kept small to reduce power consumption. In this work, we present a light-tolerant and low-power neural recording IC for motor prediction that can fully function in up to 300 $\mu \text{W}$ /mm2 of light exposure. It achieves the best-in-class power consumption of 0.57 $\mu \text{W}$ at 38 °C with a 4.1 noise efficiency factor (NEF) pseudo-resistor-less amplifier, an on- chip neural feature extractor, and individual mote-level gain control. Applying the 20-channel pre-recorded neural signals of a monkey, the IC predicts finger position and velocity with a correlation coefficient up to 0.870 and 0.569, respectively, with individual mote-level gain control enabled. In addition, wireless measurement is demonstrated through optical power and data telemetry using a custom photovoltaic (PV)/light-emitting diode (LED) GaAs chip wire bonded to the proposed IC.

Journal ArticleDOI
TL;DR: In this paper, a new bridge-type compliant displacement amplifier embedded with Scott-Russell mechanism is presented, which improves the lateral stiffness and the natural frequency in the working direction of the XY micro-positioning stage.
Abstract: This paper presents a new bridge-type compliant displacement amplifier embedded with Scott-Russell mechanism. Based on this design, a novel compliant XY micro-positioning stage is also designed, analyzed and tested to illustrate the advantages of the proposed amplifier. The main feature of the new amplifier is to employ Scott-Russell mechanism to replace one arm of the compound bridge-type mechanism, aiming to improve its lateral stiffness and the natural frequency in the working direction. The compliant XY micro-positioning stage is driven by two novel bridge-type amplifiers with orthogonal distribution. Double parallelogram guide mechanisms are added at the output ends of the bridge-type mechanisms to further lower the parasitic movements of the XY stage. Then, an analytical model based on the stiffness matrix transfer method is established for the static and dynamic characteristics of stage, which are also verified by performing finite element analysis. Finally, an experimental prototype is manufactured and its static and dynamic performances are tested. The test results demonstrate that the stage can realize a workspace of 181.0 μm × 179.5 μm with motion resolution of 20 nm and a maximum coupling error of 1.07%. The natural frequencies of XY stage along the working direction are 178 Hz and 248 Hz respectively when the PZTs are not installed or installed. Additionally, the trajectory tracking performance of the stage is also preliminarily evaluated. All of the results obtained from the analytical model, finite element analysis and experimental tests verify the effectiveness of the novel bridge-type displacement amplifier and the compliant XY micro-positioning stage.

Journal ArticleDOI
TL;DR: In this article , the authors demonstrate a waveguide amplifier on Er:LNOI, which can achieve 27.94 dB signal enhancement, 16.0 dB internal net gain (6.20 dB/cm), −8.84 dBm saturation power, 4.59 dB/mW power conversion efficiency, and 4.49 dB noise figure at 1531.6 nm.
Abstract: Erbium-doped lithium niobate on insulator (Er:LNOI) has attracted enormous interest as it provides gain and enables integrated amplifiers and lasers on the lithium niobate on insulator (LNOI) platform. We demonstrate a highly efficient waveguide amplifier on Er:LNOI. The 2.58-cm long amplifier can achieve 27.94 dB signal enhancement, 16.0 dB internal net gain (6.20 dB/cm), −8.84 dBm saturation power, 4.59 dB/mW power conversion efficiency, and 4.49 dB noise figure at 1531.6 nm. Besides, thorough investigation on the pumping wavelength, pumping scheme, output power and noise figure have been performed to provide a comprehensive understanding on this novel waveguide amplifier. This work will benefit the development of a powerful gain platform and can pave the way for a fully integrated photonic system on LNOI platform.

Journal ArticleDOI
TL;DR: In this paper , a new bridge-type compliant displacement amplifier embedded with Scott-Russell mechanism is presented, which improves the lateral stiffness and the natural frequency in the working direction of the XY micro-positioning stage.
Abstract: This paper presents a new bridge-type compliant displacement amplifier embedded with Scott-Russell mechanism. Based on this design, a novel compliant XY micro-positioning stage is also designed, analyzed and tested to illustrate the advantages of the proposed amplifier. The main feature of the new amplifier is to employ Scott-Russell mechanism to replace one arm of the compound bridge-type mechanism, aiming to improve its lateral stiffness and the natural frequency in the working direction. The compliant XY micro-positioning stage is driven by two novel bridge-type amplifiers with orthogonal distribution. Double parallelogram guide mechanisms are added at the output ends of the bridge-type mechanisms to further lower the parasitic movements of the XY stage. Then, an analytical model based on the stiffness matrix transfer method is established for the static and dynamic characteristics of stage, which are also verified by performing finite element analysis. Finally, an experimental prototype is manufactured and its static and dynamic performances are tested. The test results demonstrate that the stage can realize a workspace of 181.0 μm × 179.5 μm with motion resolution of 20 nm and a maximum coupling error of 1.07%. The natural frequencies of XY stage along the working direction are 178 Hz and 248 Hz respectively when the PZTs are not installed or installed. Additionally, the trajectory tracking performance of the stage is also preliminarily evaluated. All of the results obtained from the analytical model, finite element analysis and experimental tests verify the effectiveness of the novel bridge-type displacement amplifier and the compliant XY micro-positioning stage.

Journal ArticleDOI
TL;DR: In this article , an all-fiberized and narrow-linewidth fiber amplifier with record output power and near-diffraction-limited beam quality is presented, and the practical power limit is estimated through the maximum output powers of the fiber amplifier employing unidirectional pumping schemes.
Abstract: Abstract In this work, an all-fiberized and narrow-linewidth fiber amplifier with record output power and near-diffraction-limited beam quality is presented. Up to 6.12 kW fiber laser with the conversion efficiency of approximately 78.8% is achieved through the fiber amplifier based on a conventional step-index active fiber. At the maximum output power, the 3 dB spectral linewidth is approximately 0.86 nm and the beam quality factor is Mx2 = 1.43, My2 = 1.36. We have also measured and compared the output properties of the fiber amplifier employing different pumping schemes. Notably, the practical power limit of the fiber amplifier could be estimated through the maximum output powers of the fiber amplifier employing unidirectional pumping schemes. Overall, this work could provide a good reference for the optimal design and potential exploration of high-power narrow-linewidth fiber laser systems.

Journal ArticleDOI
TL;DR: In this paper, an amplifier-based transmissive space-time-coding metasurface is presented to realize strongly nonlinear controls of electromagnetic (EM) waves in both space and frequency domains, which can manipulate the propagation directions and adjust enhancements of nonlinear harmonic waves.
Abstract: A novel amplifier‐based transmissive space‐time‐coding metasurface is presented to realize strongly nonlinear controls of electromagnetic (EM) waves in both space and frequency domains, which can manipulate the propagation directions and adjust enhancements of nonlinear harmonic waves and break the Lorenz reciprocity due to the nonreciprocity of unilateral power amplifiers. By cascading the power amplifier between patches placed on two sides of the metasurface, the metasurface can transmit the spatial EM waves in the forward direction while blocking it in the backward direction. Two status of power amplifier biased at the standard working voltage and zero voltage are represented as codes “1” and “0,” respectively. By periodically setting adequate code sequences and proportions in the temporal dimension, according to the space‐time coding strategy, the amplitudes and phases of the harmonic transmission coefficients can be adjusted in a programmable way. A metasurface prototype is fabricated and measured in the microwave frequency to validate the concept and feasibility. The experimental results show good agreement with the theoretical predictions and numerical simulations. The proposed metasurface can achieve controllable harmonic power enhancements for flexibly configuring the power intensities in space, which enlarge and manipulate the quality of transmitting signals.

Journal ArticleDOI
TL;DR: A prototype version of the Q & U bolometric interferometer for cosmology (QUBIC) underwent a campaign of testing in the laboratory at Astroparticle Physics and Cosmology laboratory in Paris (APC) as discussed by the authors .
Abstract: A prototype version of the Q & U bolometric interferometer for cosmology (QUBIC) underwent a campaign of testing in the laboratory at Astroparticle Physics and Cosmology laboratory in Paris (APC). The detection chain is currently made of 256 NbSi transition edge sensors (TES) cooled to 320 mK. The readout system is a 128:1 time domain multiplexing scheme based on 128 SQUIDs cooled at 1 K that are controlled and amplified by an SiGe application specific integrated circuit at 40 K. We report the performance of this readout chain and the characterization of the TES. The readout system has been functionally tested and characterized in the lab and in QUBIC. The low noise amplifier demonstrated a white noise level of 0.3 nV.Hz^-0.5. Characterizations of the QUBIC detectors and readout electronics includes the measurement of I-V curves, time constant and the noise equivalent power. The QUBIC TES bolometer array has approximately 80% detectors within operational parameters. It demonstrated a thermal decoupling compatible with a phonon noise of about 5.10^-17 W.Hz^-0.5 at 410 mK critical temperature. While still limited by microphonics from the pulse tubes and noise aliasing from readout system, the instrument noise equivalent power is about 2.10^-16 W.Hz^-0.5, enough for the demonstration of bolometric interferometry.

Journal ArticleDOI
TL;DR: In this article , the forward signal amplified by a spoof plasmonic parametric amplifier is coupled to a second linear plasmoric waveguide via a spoof localized surface plasm resonator, whereas the transmission from the inverse direction is prohibited, giving rise to a measured isolation ratio of up to 20 dB.
Abstract: Driven by the miniaturization of integrated electronics, research on spoof plasmonic circuits has recently aroused widespread interest. On the other hand, nonreciprocal devices, such as isolators and circulators, are key components of integrated electronic systems. However, bulky magnets required to realize isolation and circulation prevent the application of traditional nonreciprocal technologies to integrated systems. Here, parametric amplification is explored to achieve magnetic‐free plasmonic isolation, and an ultrathin reconfigurable spoof plasmonic isolator is realized experimentally. In this isolation system, the forward signal amplified by a spoof plasmonic parametric amplifier is coupled to a second linear plasmonic waveguide via a spoof localized surface plasmon resonator, whereas the transmission from the inverse direction is prohibited, giving rise to a measured isolation ratio of up to 20 dB. By tuning the nonlinear phase‐matching condition through external bias voltage, multifrequency isolation of spoof surface plasmon polariton (SSPP) signals is also realized experimentally. This work demonstrates the possibility of producing miniaturized and low‐cost nonreciprocal SSPP devices, holding great promise for applications in nonmagnetic information processing and radar detection.