Optimized White Reflectance in Photonic Network Structures

Three-dimensional disordered networks are receiving increasing attention as versatile architectures for highly scattering materials. However, due to their complex morphology, little is still known about the interplay between their structural and optical properties. Here, we describe a simple algorithm that allows to generate photonic network structures inspired by that of the Cyphochilus beetle, famous for the bright white reflectance of its thin cuticular scales. The model allows to vary the degree of structural anisotropy and filling fraction of the network independently, revealing the key contribution of these two parameters to the overall scattering efficiency. Rigorous numerical simulations show that the obtained structures can exceed the broadband reflectance of the beetle while using less material, providing new insights for the design of advanced scattering materials.Comment: 10 pages, 3 figures. peer reviewed version, published in final form at https://doi.org/10.1002/adom.20190004

Programming of inhomogeneous resonant guided wave networks

Photonic functions are programmed by designing the interference of local waves in inhomogeneous resonant guided wave networks composed of power-splitting elements arranged at the nodes of a nonuniform waveguide network. Using a compact, yet comprehensive, scattering matrix representation of the network, the desired photonic function is designed by fitting structural parameters according to an optimization procedure. This design scheme is demonstrated for plasmonic dichroic and trichroic routers in the infrared frequency range

Modeling of bend discontinuity in plasmonic and spoof plasmonic waveguides

The paper proposes a method to characterize the bend discontinuity for plasmonic and spoof plasmonic waveguides in terms of scattering parameters. By means of this method, the waveguide is modelled by a two-port network and its scattering parameters are extracted. The parameters for the L-shaped sharp curved bends at different frequencies and under different bending angles are determined

Scattering Parameters of VHF Semiconductor Devices

Since Campbell and Foster first used scattering parameters in studying the properties of ideal transformer networks, much work has been done with scattering parameters in the analysis of microwave circuits and general lumped parameter networks. An excellent summary for micro wave circuits appears in Montgomery Dicke, and Purcell. Application of scattering parameters to network synthesis was attempted by Oono and Yasuura. Youla also extended scattering parameter theory by complex normalization. He and Penfield5 later applied scattering parameters in analyzing negative resistance amplifiers in ·conjunction with the development of the tunnel diode. The rapid development of high-frequency technologies in the past decade requires improved high-frequency measurement techniques because of the difficulty in measuring commonly-accepted immittance parameters at frequencies above 100 MHz. This difficulty stemmed from the fact that in measuring the h-, y-, or z-parameters the circuit is either in a short or open condition. The scattering parameter measurement technique is one way of overcoming this problem since the measurement circuit employs finite terminations and therefore provides more stable wide-band measurements. Along with the introduction of the scattering parameter measurement technique in high-frequency transistor measurements, attempts were made to characterize the transistors with directly measurable scattering parameters. Lange, Weinert, Anderson, Froehner, and Bodway are among those engineers who introduced the use of scattering parameters in transistor circuit design. An excellent analysis of transistor circuit design with generalized 2-port scattering parameters is given by Bodway. At the present time, the scattering parameter technique is one of the standard methods used for high-frequency transistor characterization and design

DC and radio-frequency transmission characteristics of double-walled carbon nanotubes-based ink

In this paper, double-walled carbon nanotubes (DWNTs) network layers were patterned using inkjet transfer printing. The remarkable conductive characteristics of carbon nanotubes (CNTs) are considered as promising candidates for transmission line as well as microelectronic interconnects of an arbitrary pattern. In this work, the DWNTs were prepared by the catalytic chemical vapor deposition process, oxidized and dispersed in ethylene glycol solution. The DWNTs networks were deposited between electrodes contact and then characterized at DC through current-voltage measurements, low frequency, and high frequency by scattering parameters measurements from 40 MHz up to 40 GHz through a vector network analyzer. By varying the number of inkjet overwrites, the results confirm that the DC resistance of DWNTs networks can be varied according to their number and that furthermore the networks preserve ohmic characteristics up to 100 MHz. The microwave transmission parameters were obtained from the measured S-parameter data. An algorithm is developed to calculate the propagation constant "γ", attenuation constant "α" in order to show the frequency dependence of the equivalent resistance of DWNTs networks, which decreases with increasing frequency