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2021-04-03 PIER Vol. 170, 129-152, 2021. doi:10.2528/PIER21020702

L-Band Radar Scattering and Soil Moisture Retrieval of Wheat, Canola and Pasture Fields for Smap Active Algorithms

Huanting Huang, Tien-Hao Liao, Seung Bum Kim, Xiaolan Xu, Leung Tsang, Thomas J. Jackson, and Simon Yueh

Wheat, canola, and pasture are three of the major vegetation types studied during the Soil Moisture Active Passive Validation Experiment 2012 (SMAPVEX12) conducted to support NASA's Soil Moisture Active Passive (SMAP) mission. The utilized model structure is integrated in the SMAP baseline active retrieval algorithm. Forward lookup tables (data-cubes) for VV and HH backscatters at L-band are developed for wheat and canola fields. The data-cubes have three axes: vegetation water content (VWC), root mean square (RMS) height of rough soil surface and soil permittivity. The volume scattering and doublebounce scattering of the fields are calculated using the distorted Born approximation and the coherent reflectivity in the double-bounce scattering. The surface scattering is determined by the numerical solutions of Maxwell equations (NMM3D). The results of the data-cubes are validated with airborne radar measurements collected during SMAPVEX12 for ten wheat fields, five canola fields, and three pasture fields. The results show good agreement between the data-cube simulation and the airborne data. The root mean squared errors (RMSE) were 0.82 dB, 0.78 dB, and 1.62 dB for HH, and 0.97 dB, 1.30 dB, and 1.82 dB for VV of wheat, canola, and pasture fields, respectively. The data-cubes are next used to perform the time-series retrieval of the soil moisture. The RMSEs of the soil moisture retrieval are 0.043 cm3/cm3, 0.082 cm3/cm3, and 0.082 cm3/cm3 for wheat, canola, and pasture fields, respectively. The results of this paper expand the scope of the SMAP baseline radar algorithm for wheat, canola, and pastures formed and provide a quantitative validation of its performance. It will also have applications for the upcoming NISAR (NASA-ISRO SAR Mission).

2021-02-05 PIER Vol. 170, 97-128, 2021. doi:10.2528/PIER20121201

A Fine Scale Partially Coherent Patch Model Including Topographical Effects for GNSS-R Ddm Simulations

Haokui Xu, Jiyue Zhu, Leung Tsang, and Seung Bum Kim

In this paper, we propose a fine scale partially coherent patch model (FPCP) for GNSS-R land applications for soil moisture retrieval. The land surface is divided into coherent planar patches on which microwave roughness is superimposed. The scattered waves of the coherent patch are decomposed into the coherent specular reflection and diffuse incoherent scattering. A fine scale of 2 meter patch size is chosen for the coherent patch to be applicable to complex terrain with large varieties of topographical elevations and with small to large topographical slopes. The summation of scattered fields over patches is carried out using physical optics. The phase term of the scattered wave of each patch is kept so that correlation scattering effects among patches are accounted for. Results are illustrated for power ratio for areas near the specular point and areas far away from the specular point. Comparisons are made with the radiative transfer geometric optics model. DDM simulations are performed with good agreement with CYGNSS data.

2021-02-02 PIER Vol. 170, 79-95, 2021. doi:10.2528/PIER20082001

High Efficiency Multi-Functional All-Optical Logic Gates Based on MIM Plasmonic Waveguide Structure with the Kerr-Type Nonlinear Nano-Ring Resonators

Yaw-Dong Wu

In this paper, high efficiency multi-functional all-optical logic gates based on a metal-insulator-metal (MIM) plasmonic waveguide structure with Kerr-type nonlinear nano-ring resonators are proposed. The proposed structure consists of three straight input ports, eight nano-ring resonators filled with the Kerr-type nonlinear medium, and one straight output port. By fixing the input signal power and properly changing the control power, it can be used to design high efficiency multi-functional all-optical logic gates. The numerical results show that the proposed Kerr-type nonlinear plasmonic waveguide structures could really function as all-optical XOR/NXOR, AND/NAND, and OR/NOR logic gates in the optical communication spectral region. The transmission efficiency of the high logic state is higher than 95%, and that of the low logic state is about 0% at the wavelength 1310nm. The performance of the proposed logic gates was analyzed and simulated by the finite element method (FEM).

2021-01-21 PIER Vol. 170, 63-78, 2021. doi:10.2528/PIER20122201

Computational Investigation of Nanoscale Semiconductor Devices and Optoelectronic Devices from the Electromagnetics and Quantum Perspectives by the Finite Difference Time Domain Method (Invited Review)

Huali Duan, Wenxiao Fang, Wen-Yan Yin, Erping Li, and Wenchao Chen

In the simulation of high frequency nanoscale semiconductor devices in which electromagnetic (EM) fields and carrier transport are coupled, and optoelectronic devices in which strong interactions between EM fields and charged particles exist, both the Maxwell's equations and the time-dependent Schrödinger equation (TDSE) need to be solved to capture the interactions between EM and quantum mechanics (QM). One of the numerical simulation methods for solving these equations is the finite difference time domain (FDTD) method. In this review paper, the development of FDTD method applied in EM and QM simulation is discussed. Several widely used FDTD techniques, i.e., explicit, implicit, explicit staggered-time, and Chebyshev methods, for solving the TDSE are introduced and compared. The hybrid approaches based on FDTD method, which are used to solve the Poisson-TDSE and Maxwell-TDSE coupled equations for EM-QM simulation, are also discussed. Furthermore, the applications of these simulation methods for nanoscale semiconductor devices and optoelectronic devices are introduced. Finally, a conclusion is given.

2021-01-15 PIER Vol. 170, 17-62, 2021. doi:10.2528/PIER20122108

Advanced Progress on Χ(3) Nonlinearity in Chip-Scale Photonic Platforms (Invited Review)

Zhe Kang, Chao Mei, Luqi Zhang, Zhichao Zhang, Julian Evans, Yunjun Cheng, Kun Zhu, Xianting Zhang, Dongmei Huang, Yuhua Li, Jijun He, Qiang Wu, Binbin Yan, Kuiru Wang, Xian Zhou, Keping Long, Feng Li, Qian Li, Shaokang Wang, Jinhui Yuan, Ping-Kong Alexander Wai, and Sailing He

χ(3) nonlinearity enables ultrafast femtosecond scale light-to-light coupling and manipulation of intensity, phase, and frequency. χ(3) nonlinear functionality in micro- and nano-scale photonic waveguides can potentially replace bulky fiber platforms for many applications. In this review, we summarize and comment on the progress on χ(3) nonlinearity in chip-scale photonic platforms, including several focused hot topics such as broadband and coherent sources in the new bands, nonlinear pulse shaping, and all-optical signal processing. An outlook of challenges and prospects on this hot research field is given at the end.

2021-01-14 PIER Vol. 170, 1-15, 2021. doi:10.2528/PIER20112306

Designing Nanoinclusions for Quantum Sensing Based on Electromagnetic Scattering Formalism (Invited Paper)

Constantinos Valagiannopoulos

Quantum interactions between a single particle and nanoinclusions of spherical or cylindrical shape are optimized to produce scattering lineshapes of high selectivity with respect to impinging energies, excitation directions and cavity sizes. The optimization uses a rigorous solution derived via electromagnetic scattering formalism while the adopted scheme rejects boundary extrema corresponding to resonances that occur outside of the permissible parametric domains. The reported effects may inspire experimental efforts towards designing quantum sensing systems employed in applications spanning from quantum switching and filtering to single-photon detection and quantum memory.