2020

• Record 121 of
  
  Title:Orthogonally polarized RF single sideband generation with Kerr microcombs
  
  Author(s):Moss, David J.(1); Tan, Mengxi(1); Xu, Xingyuan(2); Wu, Jiayang(1); Nguyen, Thach G.(3); Chu, Sai T.(4); Little, Brent E.(5); Mitchell, Arnan(3); Morandotti, Roberto(6,7)
  Source: TechRxiv  Volume:   Issue:   DOI: 10.36227/techrxiv.13102499  Published: October 16, 2020  
  Abstract:We review recent work on narrowband orthogonally polarized optical RF single sideband generators as well as dual-channel equalization, both based on high-Q integrated ring resonators. The devices operate in the optical telecommunications C-band and enable RF operation over a range of either fixed or thermally tuneable frequencies. They operate via TE/TM mode birefringence in the resonator. We achieve a very large dynamic tuning range of over 55 dB for both the optical carrier-to-sideband ratio and the dual-channel RF equalization for both the fixed and tunable devices. © 2020, CC BY.
  Accession Number: 20220146504
• Record 122 of
  
  Title:A Contribution Algorithm from LDRI to HDRI
  
  Author(s):Luo, Junsong(1); Qiu, Shi(2); Jiang, Yizhang(3); Cheng, Keyang(4); Ye, Huping(5); Zhang, Mingjin(6)
  Source: International Journal of Pattern Recognition and Artificial Intelligence  Volume: 34  Issue: 7  DOI: 10.1142/S0218001420590259  Published: June 30, 2020  
  Abstract:High dynamic range image (HDRI) which is combined with low dynamic range image (LDRI) needs to be mapped to a low dynamic area to display. In the process of mapping, it is impossible to determine the contribution of low dynamic image sequences in the display images, so that it results in a problem that the low dynamic images cannot be accurately selected. In this paper, for the first time, a contribution algorithm from LDRI to HDRI according to the corresponding response curve of the camera is proposed. © 2020 World Scientific Publishing Company.
  Accession Number: 20194307584549
• Record 123 of
  
  Title:Numerical investigation of radiation ablation and acceleration of high-density carbon foils
  
  Author(s):Chen, Peng(1,2,3); Hu, Ronghao(1,2,3); Zhou, Hao(1,2,3); Tao, Zhihao(1,2,3); Gao, Guilong(4); He, Kai(4); Wang, Tao(4); Tian, Jinshou(4); Yi, Tao(5); Lv, Meng(1,2,3)
  Source: Laser and Particle Beams  Volume: 38  Issue: 4  DOI: 10.1017/S0263034620000336  Published: December 2020  
  Abstract:The ablation and acceleration of diamond-like high-density carbon foils irradiated by thermal X-ray radiations are investigated with radiation hydrodynamics simulations. The time-dependent front of the ablation wave is given numerically for radiation temperatures in the range of 100-300 eV. The mass ablation rates and ablation pressures can be derived or implied from the coordinates of ablation fronts, which agree well with reported experiment results of high-density carbon with radiation temperatures Trad in the range of 160-260 eV. It is also found that the scaling law for ablation rates does not apply to Trad above 260 eV. The trajectories of targets and hydrodynamic efficiencies for different target thicknesses can be derived from the coordinates of ablation fronts using a rocket model and the results agree well with simulations. The peak hydrodynamic efficiencies of the acceleration process are investigated for different foil thicknesses and radiation temperatures. Higher radiation temperatures and target thicknesses result in higher hydrodynamic efficiencies. The simulation results are useful for the design of fusion capsules. Copyright © The Author(s) 2020. Published by Cambridge University Press.
  Accession Number: 20204509463366
• Record 124 of
  
  Title:Turing patterns in a fiber laser with a nested microresonator: Robust and controllable microcomb generation
  
  Author(s):Bao, Hualong(1); Olivieri, Luana(1); Rowley, Maxwell(1); Chu, Sai T.(2); Little, Brent E.(3); Morandotti, Roberto(4,5,6); Moss, David J.(7); Totero Gongora, Juan Sebastian(1); Peccianti, Marco(1); Pasquazi, Alessia(1)
  Source: Physical Review Research  Volume: 2  Issue: 2  DOI: 10.1103/PhysRevResearch.2.023395  Published: June 2020  
  Abstract:Microcombs based on Turing patterns have been extensively studied in configurations that can be modeled by the Lugiato-Lefever equation. Typically, such schemes are implemented experimentally by resonant coupling of a continuous wave laser to a Kerr microcavity in order to generate highly coherent and robust waves. Here, we study the formation of such patterns in a system composed of a microresonator nested in an amplifying laser cavity, a scheme recently used to demonstrate laser cavity solitons with high optical efficiency and easy repetition rate control. Utilizing this concept, we study different regimes of Turing patterns, unveiling their formation dynamics and demonstrating their controllability and robustness. By conducting a comprehensive modulational instability study with a mean-field model of the system, we explain the pattern formation in terms of its evolution from background noise, paving the way towards complete self-starting operation. Our theoretical and experimental paper provides a clear pathway for repetition rate control of these waves over both fine (Megahertz) and large (Gigahertz) scales, featuring a fractional frequency nonuniformity better than 7×10-14 with a 100-ms time gate and without the need for active stabilization. © 2020 authors. Published by the American Physical Society.
  Accession Number: 20204309390198
• Record 125 of
  
  Title:Soliton crystal 50G Hz micro-comb for Q-band microwave frequency conversion
  
  Author(s):Xu, Xingyuan(1); Wu, Jiayang(1); Tan, Mengxi(1); Nguyen, Thach G.(2); Chu, Sai T.(3); Little, Brent E.(4); Morandotti, Roberto(5,6,7); Mitchell, Arnan(2); Moss, David J.(1)
  Source: TechRxiv  Volume:   Issue:   DOI: 10.36227/techrxiv.11530251  Published: January 7, 2020  
  Abstract:We report a broadband microwave frequency converter based on a coherent Kerr optical micro-comb generated by an integrated micro-ring resonator. The coherent micro-comb displays features that are consistent with soliton crystal dynamics with an FSR of 48.9-GHz. We use this to demonstrate a high-performance millimeter-wave local oscillator at 48.9-GHz in the Q-band for microwave frequency conversion. We experimentally verify the microwave performance up to 40 GHz, achieving a ratio of −6.8 dB between output RF power and IF power and a spurious suppression ratio of > 43.5 dB. The experimental results show good agreement with theory and verify the effectiveness of microwave frequency converters based on coherent optical micro-combs, with the ability to achieve reduced size, complexity, and potential cost. © 2020, CC BY.
  Accession Number: 20220138124
• Record 126 of
  
  Title:Photonic rf and microwave arbitrary waveform generator based on a soliton crystal 49ghz kerr micro-comb
  
  Author(s):Tan, Mengxi(1); Xu, Xingyuan(1); Boes, Andreas(2); Corcoran, Bill(3); Wu, Jiayang(1); Nguyen, Thach G.(2); Chu, Sai T.(4); Little, Brent E.(5); Morandotti, Roberto(6,7); Mitchell, Arnan(2); Moss, David J.(1)
  Source: arXiv  Volume:   Issue:   DOI: null  Published: May 13, 2020  
  Abstract:We report a photonic-based radio frequency (RF) arbitrary waveform generator (AWG) using a soliton crystal micro-comb source with a free spectral range (FSR) of 48.9 GHz. The comb source provides over 80 wavelengths, or channels, that we use to successfully achieve arbitrary waveform shapes including square waveforms with a tunable duty ratio ranging from 10% to 90%, sawtooth waveforms with a tunable slope ratio of 0.2 to 1, and a symmetric concave quadratic chirp waveform with an instantaneous frequency of sub GHz. We achieve good agreement between theory and experiment, validating the effectiveness of this approach towards realizing high-performance, broad bandwidth, nearly user-defined RF waveform generation. Copyright © 2020, The Authors. All rights reserved.
  Accession Number: 20200447585
• Record 127 of
  
  Title:RF and microwave fractional differentiation with transversal filters using a soliton crystal microcomb multiwavelength source
  
  Author(s):Tan, Mengxi(1); Xu, Xingyuan(1); Corcoran, Bill(2); Wu, Jiayang(1); Boes, Andreas(3); Nguyen, Thach G.(3); Chu, Sai T.(4); Little, Brent E.(5); Morandotti, Roberto(6,7); Mitchell, Arnan(3); Moss, David J.(1)
  Source: TechRxiv  Volume:   Issue:   DOI: 10.36227/techrxiv.11530458  Published: January 7, 2020  
  Abstract:We report a photonic radio frequency (RF) fractional differentiator based on an integrated Kerr micro-comb source. The micro-comb source has a free spectral range (FSR) of 49 GHz, generating a large number of comb lines that serve as a high-performance multi-wavelength source for the differentiator. By programming and shaping the comb lines according to calculated tap weights, arbitrary fractional orders ranging from 0.15 to 0.90 are achieved over a broad RF operation bandwidth of 15.49 GHz. We experimentally characterize the frequency-domain RF amplitude and phase response as well as the temporal response with a Gaussian pulse input. The experimental results show good agreement with theory, confirming the effectiveness of our approach towards high-performance fractional differentiators featuring broad processing bandwidth, high reconfigurability, and potentially reduced sized and cost. © 2020, CC BY.
  Accession Number: 20220140654
• Record 128 of
  
  Title:Cross-Domain Brain CT Image Smart Segmentation via Shared Hidden Space Transfer FCM Clustering
  
  Author(s):Xia, Kaijian(1); Yin, Hongsheng(2); Jin, Yong(3); Qiu, Shi(4); Zhao, Hongru(5)
  Source: ACM Transactions on Multimedia Computing, Communications and Applications  Volume: 16  Issue: 2s  DOI: 10.1145/3357233  Published: July 2020  
  Abstract:Clustering is an important issue in brain medical image segmentation. Original medical images used for clinical diagnosis are often insufficient for clustering in the current domain. As there are sufficient medical images in the related domains, transfer clustering can improve the clustering performance of the current domain by transferring knowledge across the related domains. In this article, we propose a novel shared hidden space transfer fuzzy c-means (FCM) clustering called SHST-FCM for cross-domain brain computed tomography (CT) image segmentation. SHST-FCM projects both the data samples of the source domain and target domain into the shared hidden space, such that the distributions of the two domains are as close as possible. In the learned shared subspace, the data samples of the source domain serve as the auxiliary knowledge to aid the clustering process in the target domain. Extensive experiments on brain CT medical image datasets indicate the effectiveness of the proposed method. © 2020 ACM.
  Accession Number: 20203209018551
• Record 129 of
  
  Title:Optical multi-stability in a nonlinear high-order microring resonator filter
  
  Author(s):Jin, Li(1); Di Lauro, Luigi(2,3); Pasquazi, Alessia(2); Peccianti, Marco(2); Moss, David J.(4); Morandotti, Roberto(3,5); Little, Brent E.(6); Chu, Sai Tak(1)
  Source: APL Photonics  Volume: 5  Issue: 5  DOI: 10.1063/5.0002941  Published: May 1, 2020  
  Abstract:We theoretically analyze and experimentally demonstrate optical bi-stability and multi-stability in an integrated nonlinear high-order microring resonator filter based on high-index contrast doped silica glass. We use a nonlinear model accounting for both the Kerr and thermal effects to analyze the instability behavior of the coupled-resonator based filter. The model also accurately predicts the multi-stable behavior of the filter when the input frequency is slightly detuned. To understand the role of the intracavity power distribution, we investigate the detuning of the individual rings of the filter from the optical response with a pump-probe experiment. Such a measurement is performed scanning the filter with a low-power probe beam tuned a few free spectral ranges away from the resonance where the pump is coupled. A comprehensive understanding of the relationship between the nonlinear behavior and the intracavity power distribution for the high-order microring resonator filter will help the design and implementation of future all-optical switching systems using this type of filter. © 2020 Author(s).
  Accession Number: 20204409406770
• Record 130 of
  
  Title:Photonic microwave and radio frequency channelizers based on optical Kerr micro-combs
  
  Author(s):Tan, Mengxi(1); Xu, Xingyuan(2); Wu, Jiayang(1); Nguyen, Thach G.(3); Chu, Sai T.(4); Little, Brent E.(5); Morandotti, Roberto(6,7); Mitchell, Arnan(3); Moss, David J.(1)
  Source: TechRxiv  Volume:   Issue:   DOI: 10.36227/techrxiv.13077671  Published: October 11, 2020  
  Abstract:We review recent work on broadband RF channelizers based on integrated optical frequency Kerr micro-combs combined with passive micro-ring resonator filters, with microcombs having channel spacings of 200GHz and 49GHz. This approach to realizing RF channelizers offers reduced complexity, size, and potential cost for a wide range of applications to microwave signal detection. © 2020, CC BY.
  Accession Number: 20220138368
• Record 131 of
  
  Title:Improving timing performance of double-ended readout in TOF-PET detectors
  
  Author(s):Guo, L.(1,2,3,4); Tian, J.(2,4); Chen, P.(2,4); Derenzo, S.E.(1); Choong, W.-S.(1)
  Source: Journal of Instrumentation  Volume: 15  Issue: 1  DOI: 10.1088/1748-0221/15/01/P01003  Published: January 2, 2020  
  Abstract:Scintillation crystals of 20 mm length or longer are needed for clinical time-of-flight positron emission tomography (TOF-PET) to ensure effective detection efficiency for gamma photons. However, the use of long crystals would deteriorate the key performance of TOF-PET detectors, time and spatial resolution, because of the variations in the travel times of the photons in crystals and the effects of parallax errors. In this work, we studied double-ended readout TOF-PET detectors based on coupling a long scintillation crystal to SiPMs at both ends for correcting the depth-dependent effects to improve the coincidence time resolution (CTR). In particular, we focused our attention to analyze timing performance using different correction methods, including trigger times of the individual photodetectors at both ends of the crystal, the simple average of the trigger times, and the weighted average based on the inverse variances of the depth-dependent corrected trigger times. For a 3 mm × 3 mm × 25 mm unpolished lutetium fine silicate (LFS) crystal with double-ended readout and practical head-on irradiation, a CTR of 246 ps FWHM can be achieved using depth-dependent timing-correction and weighted average time method compared to 280 ps FWHM using the conventional simple average time method and 393 ps FWHM using the conventional single-ended readout. The results show that the depth-dependent timing-correction and weighted average time method in double-ended readout can effectively correct for the trigger time variations in TOF-PET detector utilizing long unpolished crystals, resulting in an improvement in the CTR of as much as 37% compared to single-ended readout. © 2020 IOP Publishing Ltd and Sissa Medialab.
  Accession Number: 20201208314004
• Record 132 of
  
  Title:Photonic RF Arbitrary Waveform Generator Based on a Soliton Crystal Micro-Comb Source
  
  Author(s):Tan, Mengxi(1); Xu, Xingyuan(1,2); Boes, Andreas(3); Corcoran, Bill(4); Wu, Jiayang(1); Nguyen, Thach G.(3); Chu, Sai T.(5); Little, Brent E.(6); Morandotti, Roberto(7,8); Mitchell, Arnan(3); Moss, David J.(1)
  Source: Journal of Lightwave Technology  Volume: 38  Issue: 22  DOI: 10.1109/JLT.2020.3009655  Published: November 15, 2020  
  Abstract:We report a photonic-based radio frequency (RF) arbitrary waveform generator (AWG) using a soliton crystal micro-comb source with a free spectral range (FSR) of 48.9 GHz. The comb source provides over 80 wavelengths, or channels, that we use to successfully achieve arbitrary waveform shapes including square waveforms with a tunable duty ratio ranging from 10% to 90%, sawtooth waveforms with a tunable slope ratio of 0.2 to 1, and a symmetric concave quadratic chirp waveform with an instantaneous frequency of sub GHz. We achieve good agreement between theory and experiment, validating the effectiveness of this approach towards realizing high-performance, broad bandwidth, nearly user-defined RF waveform generation. © 1983-2012 IEEE.
  Accession Number: 20204409441494