Browsing by Author "Huang, D"

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Open Access
Analysis of the power dependent tuning of a varactor-loaded metamaterial at microwave frequencies
(Applied Physics Letters, 2010-03-26) Huang, D; Poutrina, E; Smith, DR
We present an analysis of the nonlinear, power-dependent resonance frequency shift for two metamaterial mediums consisting of arrays of varactor-loaded split ring resonators (VLSRRs). We confirm that, over a limited range of power, a VLSRR medium can be described by its second and third order nonlinear susceptibilities, making it a useful analog medium for the quantitative investigation of other nonlinear phenomena that might be achieved using inherently nonlinear materials integrated into metamaterials. Experimental measurements of the resonance frequency shift with power from fabricated VLSRR samples are found to be in excellent agreement with the analytical model. © 2010 American Institute of Physics.
Open Access
Experimental determination of the quadratic nonlinear magnetic susceptibility of a varactor-loaded split ring resonator metamaterial
(Applied Physics Letters, 2010-07-05) Larouche, S; Rose, A; Poutrina, E; Huang, D; Smith, DR
This letter presents a quantitative measurement of the second harmonic generated by a slab of varactor loaded split ring resonator metamaterial and the retrieval of the effective quadratic nonlinear magnetic susceptibility χ(2)musing an approach based on transfer matrices. The retrieved value of χ(2)m is in excellent agreement with that predicted by an analytical effective medium theory model. © 2010 American Institute of Physics.
Open Access
Magnetic superlens-enhanced inductive coupling for wireless power transfer
(Journal of Applied Physics, 2012-03-15) Huang, D; Urzhumov, Y; Smith, DR; Hoo Teo, K; Zhang, J
We investigate numerically the use of a negative-permeability perfect lens for enhancing wireless power transfer between two current carrying coils. The negative permeability slab serves to focus the flux generated in the source coil to the receiver coil, thereby increasing the mutual inductive coupling between the coils. The numerical model is compared with an analytical theory that treats the coils as point dipoles separated by an infinite planar layer of magnetic material Urzhumov, Phys. Rev. B 19, 8312 (2011). In the limit of vanishingly small radius of the coils, and large width of the metamaterial slab, the numerical simulations are in excellent agreement with the analytical model. Both the idealized analytical and realistic numerical models predict similar trends with respect to metamaterial loss and anisotropy. Applying the numerical models, we further analyze the impact of finite coil size and finite width of the slab. We find that, even for these less idealized geometries, the presence of the magnetic slab greatly enhances the coupling between the two coils, including cases where significant loss is present in the slab. We therefore conclude that the integration of a metamaterial slab into a wireless power transfer system holds promise for increasing the overall system performance. © 2012 American Institute of Physics.
Open Access
Nonlinear oscillator metamaterial model: numerical and experimental verification.
(Opt Express, 2011-04-25) Poutrina, E; Huang, D; Urzhumov, Y; Smith, DR
We verify numerically and experimentally the accuracy of an analytical model used to derive the effective nonlinear susceptibilities of a varactor-loaded split ring resonator (VLSRR) magnetic medium. For the numerical validation, a nonlinear oscillator model for the effective magnetization of the metamaterial is applied in conjunction with Maxwell equations and the two sets of equations solved numerically in the time-domain. The computed second harmonic generation (SHG) from a slab of a nonlinear material is then compared with the analytical model. The computed SHG is in excellent agreement with that predicted by the analytical model, both in terms of magnitude and spectral characteristics. Moreover, experimental measurements of the power transmitted through a fabricated VLSRR metamaterial at several power levels are also in agreement with the model, illustrating that the effective medium techniques associated with metamaterials can accurately be transitioned to nonlinear systems.