scholarly journals Deterministic Transfer of Large-Scale β-Phase Arsenic on Fiber End Cap for Near-Infrared Ultrafast Pulse Generation

2021 ◽  
Vol 8 ◽  
Author(s):  
Qiang Yu ◽  
Cheng Chen ◽  
Kun Guo ◽  
Haiqin Deng ◽  
Tianan Yi ◽  
...  
Keyword(s):  
Large Scale ◽  
Near Infrared ◽  
Ring Cavity ◽  
Pulse Generation ◽  
Cavity Resonance ◽  
Laser Generation ◽  
Chemical Vapor Transport ◽  
Central Wavelength ◽  
Transfer Method ◽  
Ultrafast Pulse

Gray arsenic (β-phase) has aroused great attention in photonics and electronics applications, as a novel family member of two-dimensional (2D) elemental crystals of group-VA. Here, β-phase arsenic (β-As) bulk crystals were synthesized via the chemical vapor transport (CVT) method. Meanwhile, large-scale β-As nanoflake was transformed using the polydimethylsiloxane (PDMS)-assisted dry transfer method and was placed on the end cap of optical fiber with high coverage over the core area. Moreover, the β-As was used as a saturable absorber in ytterbium-doped fiber ring cavity resonance, and we demonstrated near-infrared ultrafast pulse fiber laser with the central wavelength, repetition rate, and signal-to-noise ratio (SNR) of 1,037.3 nm, 0.6 MHz, and 67.7 dB, respectively. This research demonstrates a 2D material small area deterministic transfer method and promotes the potential application of group-VA crystals in near-infrared ultrafast laser generation.

scholarly journals Performance of Graphene Nanopowder-Polyvinyl Alcohol in Optical Pulse Generation at 1.5 Micron Region

2021 ◽  
Vol 13 (3) ◽  
pp. 55
Author(s):  
Nabihah Hussain ◽  
Mohd Rashidi Salim ◽  
Asrul Izam Azmi ◽  
Muhammad Yusof Mohd Noor ◽  
Ahmad Sharmi Abdullah ◽  
...  
Keyword(s):  
Thin Film ◽  
Polyvinyl Alcohol ◽  
Fiber Laser ◽  
Saturable Absorber ◽  
Ring Cavity ◽  
Weight Ratio ◽  
Pulse Generation ◽  
Graphene Nanoplatelets ◽  
Laser Generation ◽  
Erbium Doped

This paper explains about the performance of graphene nanopowder (GNP) based saturable absorber (SA) at 1.5-micron region which is prepared by dissolution in polyvinyl alcohol (PVA) polymer. Two different GNP flakes thickness (AO2-8 nm and AO4-60 nm) are tested. By applying a solution casting method, three weight ratio of GNP to PVA (12.04, 8.03 and 3.11 wt.%) have been prepared and fabricated as a composite thin film. To characterize for the SA performance, 4 mm2 area of GNP-PVA thin film is embedded in a 14 meters long ring cavity with 3 meters Erbium doped fiber (EDF) as a gain medium. Our characterization results show that the GNP-PVA thin film act as a Q-switcher which produce stable laser pulses for 12.04 wt.% with maximum repetition rate of 39.22 kHz and shortest pulse width of 11.79 µs. Meanwhile, unstable Q-switched pulses of 8.03 wt.% and 3.11 wt.% have been observed with recorded signal to noise ratio (SNR) of only 21 dB and 17 dB, respectively. The threshold pumping power for Q-switched lasing to emerge is recorded as low as 30 mW. Apparently, it shows that GNP concentration and flakes thickness in fabricated SA composite plays vital role in the performance of generated Q-switch laser, particularly at 1.5 µm region. Full Text: PDF ReferencesT. Hasan, Z. Sun, F. Wang, F. Bonaccorso, P.H. Tan, A.G. Rozhin, A.C. Ferrari, "Nanotube–Polymer Composites for Ultrafast Photonics", Adv. Mater. 21, 3874 (2009). CrossRef Q. Bao, H. Zhang, Y. Wang, Z. Ni, Y. Yan, Z.X. Shen, K.P. Loh, D.Y. Tang, "Atomic-Layer Graphene as a Saturable Absorber for Ultrafast Pulsed Lasers", Adv. Funct. Mater. 19, 3077 (2009). CrossRef Z. Luo, M. Zhou, J. Weng, G. Huang, H. Xu, C. Ye, Z. Cai, Opt. Lett. 35(21), 3709 (2010). CrossRef D. Popa, Z. Sun, T. Hasan, F. Torrisi, F. Wang, A.C. Ferrari, "Graphene Q-switched, tunable fiber laser", Appl. Phys. Lett. 98, 3106 (2011). CrossRef Y.M. Chang, H. Kim, J.H. Lee, Y. Song, "Multilayered graphene efficiently formed by mechanical exfoliation for nonlinear saturable absorbers in fiber mode-locked lasers", Appl. Phys. Lett. 97, 211102 (2010). CrossRef M. Jiang, Z. Ren, Y. Zhang, B. Lu, R. Zhang, J. Guo, Y. Zhou, J. Bai, "Passive Q-Switching with Graphene Saturable Absorber in Nd:YAG Operating at 1064nm", Mater. Sci. Forum 694, 700 (2011). CrossRef N. Hussin, M.H. Ibrahim, F. Ahmad, H. Yahaya, S.W. Harun, "Graphene Nanoplatelets (GnP)-PVA Based Passive Saturable Absorber", Telkomnika 15(2), 814 (2017). CrossRef F.C. Mat, M. Yasin, A.A. Latiff, S.W. Harun, Photonics Letters of Poland 9, 100 (2017). CrossRef E.K. Ng, K.Y. Lau, H.K. Lee, N.M. Yusoff, A.R. Sarmani, M.F. Omar, M.A. Mahdi, "L-band femtosecond fiber laser based on a reduced graphene oxide polymer composite saturable absorber", Opt. Mater. Express 11, 59 (2021). CrossRef N.H.M. Apandi, S.N.F. Zuikafly, N. Kasim, M.A. Mohamed, S.W. Harun, F. Ahmad, "Observation of dark and bright pulses in q-switched erbium doped fiber laser using graphene nano-platelets as saturable absorber", Bull. Electr. Eng. Inform. 8, 1358 (2019). CrossRef N.U.H.H.B. Zalkepali, N.A. Awang, Y.R. Yuzaile, Z. Zakaria, A.A. Latif and F. Ahmad, "Graphene Nanoplatelets as Saturable Absorber for Mode-locked Fiber Laser Generation", J. Adv. Res. Dyn. Control Syst. 12(2), 602 (2020). CrossRef X. Zhu and S. Chen, "Autoencoder-Based Transceiver Design for OWC Systems in Log-Normal Fading Channel", IEEE Photonics J. 11, 7105109 (2019). CrossRef

scholarly journals An optical observational cluster mass function at z ∼ 1 with the ORELSE survey

2021 ◽  
Vol 502 (3) ◽  
pp. 3942-3954
Author(s):  
D Hung ◽  
B C Lemaux ◽  
R R Gal ◽  
A R Tomczak ◽  
L M Lubin ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Large Scale ◽  
Near Infrared ◽  
Function Analysis ◽  
Voronoi Tessellation ◽  
Cosmological Parameters ◽  
Mass Range ◽  
Mass Function ◽  
Cluster Mass ◽  
Theoretical Mass

ABSTRACT We present a new mass function of galaxy clusters and groups using optical/near-infrared (NIR) wavelength spectroscopic and photometric data from the Observations of Redshift Evolution in Large-Scale Environments (ORELSE) survey. At z ∼ 1, cluster mass function studies are rare regardless of wavelength and have never been attempted from an optical/NIR perspective. This work serves as a proof of concept that z ∼ 1 cluster mass functions are achievable without supplemental X-ray or Sunyaev-Zel’dovich data. Measurements of the cluster mass function provide important contraints on cosmological parameters and are complementary to other probes. With ORELSE, a new cluster finding technique based on Voronoi tessellation Monte Carlo (VMC) mapping, and rigorous purity and completeness testing, we have obtained ∼240 galaxy overdensity candidates in the redshift range 0.55 < z < 1.37 at a mass range of 13.6 < log (M/M⊙) < 14.8. This mass range is comparable to existing optical cluster mass function studies for the local universe. Our candidate numbers vary based on the choice of multiple input parameters related to detection and characterization in our cluster finding algorithm, which we incorporated into the mass function analysis through a Monte Carlo scheme. We find cosmological constraints on the matter density, Ωm, and the amplitude of fluctuations, σ8, of $\Omega _{m} = 0.250^{+0.104}_{-0.099}$ and $\sigma _{8} = 1.150^{+0.260}_{-0.163}$. While our Ωm value is close to concordance, our σ8 value is ∼2σ higher because of the inflated observed number densities compared to theoretical mass function models owing to how our survey targeted overdense regions. With Euclid and several other large, unbiased optical surveys on the horizon, VMC mapping will enable optical/NIR cluster cosmology at redshifts much higher than what has been possible before.

scholarly journals Principal component analysis tomography in near-infrared integral field spectroscopy of young stellar objects – I. Revisiting the high-mass protostar W33A

2021 ◽  
Vol 503 (1) ◽  
pp. 270-291
Author(s):  
F Navarete ◽  
A Damineli ◽  
J E Steiner ◽  
R D Blum
Keyword(s):  
Large Scale ◽  
Near Infrared ◽  
Rotation Axis ◽  
Principal Component ◽  
Young Stellar Objects ◽  
High Mass ◽  
Continuum Emission ◽  
Rotating Disc ◽  
Stellar Objects ◽  
K Band

ABSTRACT W33A is a well-known example of a high-mass young stellar object showing evidence of a circumstellar disc. We revisited the K-band NIFS/Gemini North observations of the W33A protostar using principal components analysis tomography and additional post-processing routines. Our results indicate the presence of a compact rotating disc based on the kinematics of the CO absorption features. The position–velocity diagram shows that the disc exhibits a rotation curve with velocities that rapidly decrease for radii larger than 0.1 arcsec (∼250 au) from the central source, suggesting a structure about four times more compact than previously reported. We derived a dynamical mass of 10.0$^{+4.1}_{-2.2}$ $\rm {M}_\odot$ for the ‘disc + protostar’ system, about ∼33 per cent smaller than previously reported, but still compatible with high-mass protostar status. A relatively compact H2 wind was identified at the base of the large-scale outflow of W33A, with a mean visual extinction of ∼63 mag. By taking advantage of supplementary near-infrared maps, we identified at least two other point-like objects driving extended structures in the vicinity of W33A, suggesting that multiple active protostars are located within the cloud. The closest object (Source B) was also identified in the NIFS field of view as a faint point-like object at a projected distance of ∼7000 au from W33A, powering extended K-band continuum emission detected in the same field. Another source (Source C) is driving a bipolar $\rm {H}_2$ jet aligned perpendicular to the rotation axis of W33A.

Gram-scale synthesis of a neodymium chelate as a spectral CT and second near-infrared window imaging agent for visualizing the gastrointestinal tract in vivo

2021 ◽  
Author(s):  
Pengrui Zhuang ◽  
Ke Xiang ◽  
Xiangxi Meng ◽  
Guohe Wang ◽  
Ziyuan Li ◽  
...  
Keyword(s):  
Gastrointestinal Tract ◽  
Fluorescence Imaging ◽  
Large Scale ◽  
Near Infrared ◽  
Imaging Agent ◽  
Spectral Ct ◽  
Green Method ◽  
Infrared Window

A facile and green method was developed to fabricate Nd-DTPA on a large scale without byproducts for CT/spectral CT and NIR II fluorescence imaging of the gastrointestinal tract in vivo.

scholarly journals A Confrontation Decision-Making Method with Deep Reinforcement Learning and Knowledge Transfer for Multi-Agent System

Symmetry ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 631
Author(s):  
Chunyang Hu
Keyword(s):  
Decision Making ◽  
Reinforcement Learning ◽  
Knowledge Transfer ◽  
Large Scale ◽  
Effective Control ◽  
Small Scale ◽  
Learning Agent ◽  
Multi Agent ◽  
Transfer Method ◽  
Parameter Sharing

In this paper, deep reinforcement learning (DRL) and knowledge transfer are used to achieve the effective control of the learning agent for the confrontation in the multi-agent systems. Firstly, a multi-agent Deep Deterministic Policy Gradient (DDPG) algorithm with parameter sharing is proposed to achieve confrontation decision-making of multi-agent. In the process of training, the information of other agents is introduced to the critic network to improve the strategy of confrontation. The parameter sharing mechanism can reduce the loss of experience storage. In the DDPG algorithm, we use four neural networks to generate real-time action and Q-value function respectively and use a momentum mechanism to optimize the training process to accelerate the convergence rate for the neural network. Secondly, this paper introduces an auxiliary controller using a policy-based reinforcement learning (RL) method to achieve the assistant decision-making for the game agent. In addition, an effective reward function is used to help agents balance losses of enemies and our side. Furthermore, this paper also uses the knowledge transfer method to extend the learning model to more complex scenes and improve the generalization of the proposed confrontation model. Two confrontation decision-making experiments are designed to verify the effectiveness of the proposed method. In a small-scale task scenario, the trained agent can successfully learn to fight with the competitors and achieve a good winning rate. For large-scale confrontation scenarios, the knowledge transfer method can gradually improve the decision-making level of the learning agent.

Real time in-line monitoring of large scale Bacillus fermentations with near-infrared spectroscopy

2014 ◽  
Vol 189 ◽  
pp. 120-128 ◽  
Author(s):  
José Alves-Rausch ◽  
Roland Bienert ◽  
Christian Grimm ◽  
Dirk Bergmaier
Keyword(s):  
Infrared Spectroscopy ◽  
Real Time ◽  
Near Infrared Spectroscopy ◽  
Large Scale ◽  
Near Infrared

Optimization of Mamyshev regenerator for ultrafast pulse generation

2021 ◽  
Author(s):  
Mikko Närhi ◽  
Andrei Fedotov ◽  
Kseniia Aksenova ◽  
Regina Gumenyuk
Keyword(s):  
Pulse Generation ◽  
Ultrafast Pulse Generation ◽  
Ultrafast Pulse

scholarly journals Integrated Multi-channel PPG and ECG System for Cardiovascular Risk Assessment

Proceedings ◽  
2019 ◽  
Vol 27 (1) ◽  
pp. 8 ◽  
Author(s):  
David Perpetuini ◽  
Antonio Maria Chiarelli ◽  
Vincenzo Vinciguerra ◽  
Piergiusto Vitulli ◽  
Sergio Rinella ◽  
...  
Keyword(s):  
Cardiovascular Risk ◽  
Arterial Stiffness ◽  
Pressure Wave ◽  
Large Scale ◽  
Near Infrared ◽  
Infrared Light ◽  
Invasive Technique ◽  
Cardiovascular Risk Assessment ◽  
Non Invasive ◽  
Cuff Occlusion

Photoplethysmography (PPG) is a non-invasive technique that employs near infrared light to estimate periodic oscillations in blood volume within arteries caused by the pulse pressure wave. Importantly, combined Electrocardiography (ECG) and PPG can be employed to quantify arterial stiffness. The capabilities of a home-made multi-channel PPG-ECG device (7 PPG probes, 4 ECG derivations) to evaluate arterial ageing were assessed. The high numerosity of channels allowed to estimate arterial stiffness at multiple body locations, without supra-systolic cuff occlusion, providing a fast and accurate examination of cardiovascular status and potentially allowing large scale clinical screening of cardiovascular risk.

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