2019
2019
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Record 625 of
Title:Topographic Evolution of Von Kármán Crater Revealed by the Lunar Rover Yutu-2
Author(s):Di, Kaichang(1,2); Zhu, Meng-Hua(2); Yue, Zongyu(1); Lin, Yangting(3); Wan, Wenhui(1); Liu, Zhaoqin(1); Gou, Sheng(1,2); Liu, Bin(1); Peng, Man(1); Wang, Yexin(1); Niu, Shengli(1); Zhang, Jinhai(3); Li, Jian(4); Xie, Jianfeng(4); Xi, Luhua(4); Yang, Jianfeng(5); Xue, Bin(5)Source: Geophysical Research Letters Volume: 46 Issue: 22 DOI: 10.1029/2019GL085252 Published: November 28, 2019Abstract:Chang'e-4 (CE-4) achieved the first farside landing in Von Kármán crater. In the landing site, linear features have been identified previously from SLDEM and considered to be ejecta from the neighboring Finsen crater. The 5 cm grid spacing digital elevation model of the landing site, generated from the rover's panoramic images, provides more details of the rugged terrain. We further interpret the superimposition of NE-SW ejecta from Finsen crater on the underlying SE-NW dome-like surface relief from Alder crater. The landing site is ~70 m higher than the mare basalts within Von Kármán crater. Numerical simulations predict ~30 and ~35 m ejecta deposited at the landing site from Finsen and Alder craters, respectively. The good agreement between the digital elevation model data and ejecta predicted thickness reveals the topographic evolution of Von Kármán crater, indicating that the rover-measured material is excavated from Finsen crater with possible contributions from Alder crater. ?2019. American Geophysical Union. All Rights Reserved.Accession Number: 20194807747035 -
Record 626 of
Title:CMOS-compatible high-index doped silica waveguide with an embedded silicon-nanocrystal strip for all-optical analog-to-digital conversion
Author(s):Li, Yuhua(1); Zhu, Kun(2); Kang, Zhe(2); Lok Ho, Wai(1); Davidson, Roy(3); Lu, Chao(2); Little, Brent E.(4); Chu, Sai Tak(1)Source: Photonics Research Volume: 7 Issue: 10 DOI: 10.1364/PRJ.7.001200 Published: 2019Abstract:Passive all-optical signal processors that overcome the electronic bottleneck can potentially be the enabling components for the next-generation high-speed and lower power consumption systems. Here, we propose and experimentally demonstrate a CMOS-compatible waveguide and its application to the all-optical analog-to-digital converter (ADC) under the nonlinear spectral splitting and filtering scheme. As the key component of the proposed ADC, a 50 cm long high-index doped silica glass spiral waveguide is composed of a thin silicon-nanocrystal (Si-nc) layer embedded in the core center for enhanced nonlinearity. The device simultaneously possesses low loss (0.16 dB/cm at 1550 nm), large nonlinearity (305 W?1∕km at 1550 nm), and negligible nonlinear absorption. A 2-bit ADC basic unit is achieved when pumped by the proposed waveguide structure at the telecom band and without any additional amplification. Simulation results that are consistent with the experimental ones are also demonstrated, which further confirm the feasibility of the proposed scheme for larger quantization resolution. This demonstrated approach enables a fully monolithic solution for all-optical ADC in the future, which can digitize broadband optical signals directly at low power consumption. This has great potential on the applications of high-speed optical communications, networks, and signal processing systems. ? 2019 Chinese Laser PressAccession Number: 20194207529141 -
Record 627 of
Title:Planar and ridge waveguides in Yb3+-doped silicate glasses fabricated by proton implantation and precise diamond blade dicing
Author(s):Zhang, Jie(1); Guo, Wen-Tao(1); Tang, Chen-Yang(1); Yan, Sen(1); Li, Wei-Nan(2); Liu, Chun-Xiao(1)Source: Optics Communications Volume: 453 Issue: DOI: 10.1016/j.optcom.2019.124344 Published: 15 December 2019Abstract:We firstly report on the planar waveguide via the single-energy proton implantation in the Yb3+-doped silicate glass. The implanted energy and fluence are 400 keV and 8.0×1016 ions/cm2, respectively. The thermal treatment at 200 °C for 1h was used to optimize waveguiding characteristics. The guided-mode spectra in the planar waveguide before and after annealing were characterized by the m-line method at 632.8 and 1539 nm. The distributions of refractive index for the as-implanted and annealed planar waveguides were reconstructed by the reflectivity calculation method. The optical characterizations were conducted at 632.8 nm using the end-fire coupling method before and after the thermal treatment. Then, the ridge waveguide was formed by the precise diamond blade dicing on the annealed planar Yb3+-doped silicate glass waveguide. The microscope image and near-field intensity profile of the ridge waveguide were investigated by the metallographic microscope and the end-face coupling system, respectively. ? 2019 Elsevier B.V.Accession Number: 20193307311177