Publications

@article{nokey,

title = {Conformal Frequency Selective Surfaces for Arbitrary Curvature},

author = {Cesar L. Valle and Gilbert T. Carranza and Raymond C. Rumpf},

url = {https://ieeexplore.ieee.org/abstract/document/9933174/keywords#keywords},

doi = {10.1109/TAP.2022.3216960},

issn = {1558-2221},

year  = {2022},

date = {2022-10-31},

urldate = {2022-10-31},

journal = {IEEE Transactions on Antennas and Propagation},

volume = {71},

issue = {1},

pages = {612-620},

abstract = {An algorithm is introduced for generating frequency selective surfaces (FSS) capable of conforming to any curvature while maintaining proper size, shape and spacing of the elements. Compared to traditional projection and mapping methods, the presented algorithm maintains the electromagnetic properties of the FSS array despite the curvature. The algorithm can be used to conform to radomes, parts of autonomous vehicles, or any surface. The algorithm is agnostic to both element design and surface curvature. This allows the user to design a FSS for any curved surface while maintaining its response comparable to a flat array. The algorithm outputs two standard tessellation language (STL) files, one describing the curved surface and the other the elements of the FSS placed onto the curved surface. This makes the algorithm suitable for 3D printing using systems with more than three axes or for flexible electronics. Several examples of arbitrary surfaces are shown. Lastly, the algorithm was applied to a Jerusalem-cross FSS on a non-symmetrical parabolic dome. The dimensions of the parabolic dome were chosen to test the response of the array on a rather extreme surface against a projected array on the same surface. Simulations were carried out using Ansys HFSS from the infinite array to finite arrays to confirm operation. Three test surfaces were manufactured with measured results found to be in good agreement with simulation.},

keywords = {arbitrary conformal array, conformal frequency selective surface, finite element analysis, frequency selective surface (FSS), gratings, periodic structures, strain, surface fitting},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Dynamical Control of Multilayer Spacetime Structures using Extended Fourier Modal Method},

author = {Khorrami, Yaser and Fathi, Davood and Khavasi, Amin and Rumpf, Raymond},

url = {https://ieeexplore.ieee.org/document/9585376},

doi = {10.1109/JPHOT.2021.3122371},

isbn = {1943-0655},

year  = {2021},

date = {2021-10-26},

urldate = {2021-10-26},

journal = {IEEE Photonics Journal},

abstract = {We introduce two-dimensional space plus time (2D+1) structure and numerically investigate it using a developed multilayer simulation framework, for the first time. The new structure is consisting of crossed grating with time-varying permittivity which is inspired from 1D+1. In this regard, we extend Fourier Modal Method (FMM) in a general approach for spacetime multilayer states. Our proposed framework is fast, robust, and powerful compared to various finite difference methods. We use the scattering matrix technique to develop the proposed spacetime simulation method for multilayer structures using a non-uniform stack of layers. The method is perfectly suitable to investigate the spatiotemporal effects of surfaces/metasurfaces which covers both the transverse electric and magnetic (TE & TM) polarizations. The results show more freedom to control the optical outcomes of the multilayer considering two spatial periodicities in addition to the modulation frequency to reach nonreciprocity as one of the main consequences of the proposed structure. Moreover, we investigate the condition and limitation of breaking the Lorentz rule for spacetime structures. 2D+1 structure is more controllable than the 1D+1 due to its greater ability to adjust spatial manipulation in addition to temporal variations to reach nonreciprocity applications, digital coding, beam steering, etc.},

keywords = {diffractive optics, frequency modulation, gratings, nonhomogeneous media, optical diffraction, optical polarization, optical transmitters, permittivity},

pubstate = {published},

tppubtype = {article}

}

@article{RN27,

title = {Guided mode resonance filter as a spectrally selective feedback element in a double-cladding optical fiber laser},

author = {Alok A Mehta and Raymond C Rumpf and Zachary A Roth and Eric G Johnson},

url = {https://ieeexplore.ieee.org/document/4390072},

doi = {10.1109/LPT.2007.908776},

issn = {1041-1135},

year  = {2007},

date = {2007-11-27},

journal = {IEEE Photonics Technology Letters},

volume = {19},

number = {24},

pages = {2030-2032},

abstract = {In this work, a spectrally selective optical element is introduced based on a 2-D guided mode resonance filter (GMRF) as an external feedback element. The GMRF was designed to provide a highly efficient narrow linewidth reflection within the gain bandwidth of the fiber laser, while transmitting the pump beam. These features enabled the fiber laser to operate in an external cavity configuration to provide a wavelength-stabilized and narrow linewidth output within the optical -band.},

keywords = {gratings, lasers, optical fiber, optical resonance},

pubstate = {published},

tppubtype = {article}

}