- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Chip-Scale Molecular Clock
摘要： An ultra-stable time-keeping device is presented, which locks its output clock frequency to the rotational-mode transition of polar gaseous molecules. Based on a high-precision spectrometer in the sub-terahertz (THz) range, our new clocking scheme realizes not only fully electronic operation but also implementations using mainstream CMOS technology. Meanwhile, the small wavelength of probing wave and high absorption intensity of our adopted molecules (carbonyl sulfide, 16O12C32S) also enable miniaturization of the gas cell. All these result in an 'atomic-clock-grade' frequency reference with small size, power, and cost. This paper provides the architectural and chip-design details of the first proof-of-concept molecular clock using a 65-nm CMOS bulk technology. Using a 231.061-GHz phase-locked loop (PLL) with frequency-shift keying (FSK) modulation and a sub-THz FET detector with integrated lock-in function, the chip probes the accurate transition frequency of carbonyl sulfide (OCS) gas inside a single-mode waveguide, and accordingly adjusts the 80-MHz output of a crystal oscillator. The clock consumes only 66 mW of dc power and has a measured Allan deviation of 3.8 × 10^{-10} at an averaging time of τ = 1000 s.
关键词： CMOS,molecular clock,rotational spectroscopy,Allan deviation,GPS,carbonyl sulfide (OCS),frequency stability,navigation
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE Energy Conversion Congress and Exposition (ECCE) - Portland, OR, USA (2018.9.23-2018.9.27)] 2018 IEEE Energy Conversion Congress and Exposition (ECCE) - Current-Fed Quasi Z-Source Inverter Based PV Distributed Generation Controller
摘要： Recently, the renewable photovoltaic distributed generation (PV-DG) enjoys a rapid growth globally due to the advancement in solar systems and power electronics technologies. However, the intermittent nature of solar radiation and performance of the attached power converters, inevitably poses some challenges to the power grids integrated large-scale solar-farms (SF). These challenges include frequency oscillations, voltage variation and power quality issues. To overcome these problems, this study proposes a Current-Fed quasi Z-source Inverter (CF-qZSI) as an alternative converter for distribution generation controllers to facilitate the integration of a PV energy source into a weak power system. The detailed model of the CF-qZSI-based distribution controller (CqZDC) and its control system are developed. The dynamic performance of the CqZDC device is evaluated to validate different objectives using an actual field data and RTDS simulation platform.
关键词： frequency stability,current source inverter,wide band gap devices,Accommodation of renewable energy resources,power quality improving,facilitating of distributed electricity generations
更新于2025-09-23 15:23:52
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[IEEE 2019 Compound Semiconductor Week (CSW) - Nara, Japan (2019.5.19-2019.5.23)] 2019 Compound Semiconductor Week (CSW) - Mid-infrared photoresponse and robotic fabrication of graphene/h-BN van der Waals heterostructures
摘要： This paper introduces the parabolic variance (PVAR), a wavelet variance similar to the Allan variance (AVAR), based on the linear regression (LR) of phase data. The companion article arXiv:1506.05009 [physics.ins-det] details the Ω frequency counter, which implements the LR estimate. The PVAR combines the advantages of AVAR and modified AVAR (MVAR). PVAR is good for long-term analysis because the wavelet spans over 2τ, the same as the AVAR wavelet, and good for short-term analysis because the response to white and flicker PM is 1/τ3 and 1/τ2, the same as the MVAR. After setting the theoretical framework, we study the degrees of freedom and the confidence interval for the most common noise types. Then, we focus on the detection of a weak noise process at the transition—or corner—where a faster process rolls off. This new perspective raises the question of which variance detects the weak process with the shortest data record. Our simulations show that PVAR is a fortunate tradeoff. PVAR is superior to MVAR in all cases, exhibits the best ability to divide between fast noise phenomena (up to flicker FM), and is almost as good as AVAR for the detection of random walk and drift.
关键词： atomic frequency standard,frequency noise,measurement uncertainty,oscillator,frequency stability,Allan variance,flicker,phase noise
更新于2025-09-23 15:19:57
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Laser frequency shift up to 5 GHz with a high-efficiency 12-pass 350-MHz acousto-optic modulator
摘要： We demonstrate a novel laser frequency shift scheme using a 12-pass 350-MHz acousto-optic modulator (AOM). This AOM system shows better performance compared to ordinary acousto-optic modulation schemes. The frequency of the incident laser beam is shifted by 4.2 GHz with the total diffraction efficiency as high as 11%, and the maximum frequency shift is 5 GHz. Combining the ±1st order diffraction, laser signals with up to 10 GHz frequency difference can be obtained, which fulfill most frequency shift requirements of laser cooling and coherent manipulation experiments with alkali metal atoms.
关键词： frequency stability,diffraction efficiency,acousto-optic modulator,multi-pass AOM,laser frequency shift
更新于2025-09-23 15:19:57
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Shaped Accelerating Beams for Materials Processing
摘要： This paper introduces the parabolic variance (PVAR), a wavelet variance similar to the Allan variance (AVAR), based on the linear regression (LR) of phase data. The companion article arXiv:1506.05009 [physics.ins-det] details the Ω frequency counter, which implements the LR estimate. The PVAR combines the advantages of AVAR and modified AVAR (MVAR). PVAR is good for long-term analysis because the wavelet spans over 2τ, the same as the AVAR wavelet, and good for short-term analysis because the response to white and flicker PM is 1/τ3 and 1/τ2, the same as the MVAR. After setting the theoretical framework, we study the degrees of freedom and the confidence interval for the most common noise types. Then, we focus on the detection of a weak noise process at the transition—or corner—where a faster process rolls off. This new perspective raises the question of which variance detects the weak process with the shortest data record. Our simulations show that PVAR is a fortunate tradeoff. PVAR is superior to MVAR in all cases, exhibits the best ability to divide between fast noise phenomena (up to flicker FM), and is almost as good as AVAR for the detection of random walk and drift.
关键词： atomic frequency standard,frequency noise,measurement uncertainty,oscillator,frequency stability,Allan variance,flicker,phase noise
更新于2025-09-19 17:13:59
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[IEEE 2019 Joint Conference of the IEEE International Frequency Control Symposium anEuropean Frequency and Time Forum (EFTF/IFC) - Orlando, FL, USA (2019.4.14-2019.4.18)] 2019 Joint Conference of the IEEE International Frequency Control Symposium and European Frequency and Time Forum (EFTF/IFC) - Ultrastable Laser System Using Room-Temperature Optical Cavity with 4.8??10 <sup>a??17</sup> Thermal Noise Limit
摘要： A new clock laser system using an optical cavity with 4.8×10-17 thermal noise limit has been developed for rapid evaluation of ytterbium lattice clocks. This was realized by using a 30-cm-long ULE cavity, fused-silica mirror substrates, and crystalline mirror coatings. The frequency stability of the beating signal between the new clock laser and the old clock laser was limited by the latter. The linewidth and the frequency stability of the new clock laser will be measured by comparing the frequency between two similar systems.
关键词： linewidth,ytterbium,optical lattice clock,frequency stability,optical cavity,clock laser,crystalline coating
更新于2025-09-19 17:13:59
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Characterization and applications of auto-locked vacuum-sealed diode lasers for precision metrology
摘要： We demonstrate the performance characteristics of a new class of vacuum-sealed, autolocking diode laser systems and their applications to precision metrology. The laser is based on adaptations of a design that uses optical feedback from an interference filter and it includes a vacuum-sealed cavity, an interchangeable base-plate, and an autolocking digital controller. A change of the base-plate allows operation at desired wavelengths in the visible and near infrared spectral range, whereas the autolocking ability allows the laser to be tuned and frequency stabilized with respect to atomic, molecular, and solid-state resonances without human intervention using a variety of control algorithms programmed into the same controller. We characterize the frequency stability of this laser system based on the Allan deviation (ADEV) of the beat note and of the lock signal. We find that the ADEV floor of 2 × 10?12 and short-term linewidth of ～200 kHz are strongly influenced by current noise and vacuum sealing. Reducing the current noise and cavity pressure decreases the ADEV floor and increases the averaging time at which the floor occurs, which is a signature of long-term stability. We also show that evacuating the cavity to ～1 Torr reduces the range of the correction signal of the feedback loop by approximately one order of magnitude, thereby increasing the lock range of the controller. The long-term stability allows the laser to be incorporated into a commercial gravimeter for accurate measurements of gravitational acceleration at the level of a few parts-per-billion, which are comparable to values obtained with an iodine-stabilized He–Ne laser. The autolocking and pattern-matching features of the controller allow the laser to be tuned and stabilized with respect to a temperature tunable transmission spectrum of a fiber-Bragg grating. This capability may be suitable for the development of a differential absorption LIDAR transmitter that can generate data at both on-line and off-line lock points using a single laser.
关键词： precision metrology,autolocking,frequency stability,LIDAR,vacuum-sealed,diode laser,gravimeter
更新于2025-09-19 17:13:59
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Multipoint and energy-equal fiber-optic laser-ultrasonic actuator based on peanut-shaped structures
摘要： This paper introduces the parabolic variance (PVAR), a wavelet variance similar to the Allan variance (AVAR), based on the linear regression (LR) of phase data. The companion article arXiv:1506.05009 [physics.ins-det] details the Ω frequency counter, which implements the LR estimate. The PVAR combines the advantages of AVAR and modified AVAR (MVAR). PVAR is good for long-term analysis because the wavelet spans over 2τ, the same as the AVAR wavelet, and good for short-term analysis because the response to white and flicker PM is 1/τ3 and 1/τ2, the same as the MVAR. After setting the theoretical framework, we study the degrees of freedom and the confidence interval for the most common noise types. Then, we focus on the detection of a weak noise process at the transition—or corner—where a faster process rolls off. This new perspective raises the question of which variance detects the weak process with the shortest data record. Our simulations show that PVAR is a fortunate tradeoff. PVAR is superior to MVAR in all cases, exhibits the best ability to divide between fast noise phenomena (up to flicker FM), and is almost as good as AVAR for the detection of random walk and drift.
关键词： frequency stability,flicker,atomic frequency standard,Allan variance,phase noise,frequency noise,oscillator,measurement uncertainty
更新于2025-09-16 10:30:52
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[IEEE 2019 International Conference on Electrical and Computing Technologies and Applications (ICECTA) - Ras Al Khaimah, United Arab Emirates (2019.11.19-2019.11.21)] 2019 International Conference on Electrical and Computing Technologies and Applications (ICECTA) - Miniature Dual-Band Band-Pass Filter Using Slotted Ring Resonators and Coupled lines for L and S Bands Communication
摘要： This paper introduces the parabolic variance (PVAR), a wavelet variance similar to the Allan variance (AVAR), based on the linear regression (LR) of phase data. The companion article arXiv:1506.05009 [physics.ins-det] details the Ω frequency counter, which implements the LR estimate. The PVAR combines the advantages of AVAR and modified AVAR (MVAR). PVAR is good for long-term analysis because the wavelet spans over 2τ, the same as the AVAR wavelet, and good for short-term analysis because the response to white and flicker PM is 1/τ3 and 1/τ2, the same as the MVAR. After setting the theoretical framework, we study the degrees of freedom and the confidence interval for the most common noise types. Then, we focus on the detection of a weak noise process at the transition—or corner—where a faster process rolls off. This new perspective raises the question of which variance detects the weak process with the shortest data record. Our simulations show that PVAR is a fortunate tradeoff. PVAR is superior to MVAR in all cases, exhibits the best ability to divide between fast noise phenomena (up to flicker FM), and is almost as good as AVAR for the detection of random walk and drift.
关键词： atomic frequency standard,frequency noise,measurement uncertainty,oscillator,frequency stability,Allan variance,flicker,phase noise
更新于2025-09-16 10:30:52
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Grid Connected-Photovoltaic System (GC-PVS): Issues and Challenges
摘要： Smart grid is the key technology for an effective utilization of the Renewable Energy Sources (RES). The utilization of RES for the generation of electricity is increasingly gaining interest of researchers during the last decades. The main reason behind this is global incentivization, the increasing price of petroleum products, climate issues and deregulations in the energy market. As the Government of India, (MNRE i.e. Ministry of New & Renewable Energy) is targeting to generate 20000 MW power through grid-connected solar PVS by the year 2022 therefore, the main focus in this paper has been presented on power generation through grid-connected PVS. The emerging smart grid technology has enabled the grid-connected PVS as an evolving process in today’s world for electrical power generation. However, apart from so many advantages, there are several issues and challenges associated with the integration of PVS to the electric utility grid hence, the investigation to find out available possible solutions to overcome these issues becomes essential in order to enhance the performance of grid-connected PVS. The most severe constraint associated with this emerging technology is it high penetration level. If during low load conditions there is some mismatch found between the real power output and the load profile characteristics of PVS then it may result into large reverse power flow, high power losses or severe voltage violation. In this paper, several issues and challenges associated with the integration of solar PVS with the electric utility grid are presented.
关键词： Renewable Energy Sources,Grid Connected-Photovoltaic System,harmonics,voltage stability,RES,frequency stability,smart grid,GC-PVS
更新于2025-09-11 14:15:04