A General Framework for the Finite-Difference Time-Domain Simulation of Real Metals

Pernice, Wolfram; Payne, F.P.; Gallagher, Dominic F. G.

doi:10.1109/tap.2007.891853

Cited by 19 publications

(21 citation statements)

References 24 publications

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“…We analyze the transmission properties of the ring resonator device using coupled modetheory [16] (CMT) and finite-difference time-domain simulations [17]. Here a micro-ring resonator with a radius of 10µm is considered, which provides a small footprint nanophotonic circuit element.…”

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confidence: 99%

Photonic non-volatile memories using phase change materials

Pernice¹,

Bhaskaran²

2012

Applied Physics Letters

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153

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We propose an all-photonic, non-volatile memory and processing element based on phase-change thin-films deposited onto nanophotonic waveguides. Using photonic microring resonators partially covered with Ge 2 Sb 2 Te 5 (GST) multi-level memory operation in integrated photonic circuits can be achieved. GST provides a dramatic change in refractive index upon transition from the amorphous to crystalline state, which is exploited to reversibly control both the extinction ratio and resonance wavelength of the microcavity with an additional gating port in analogy to optical transistors. Our analysis shows excellent sensitivity to the degree of crystallization inside the GST, thus providing the basis for non-von Neuman neuromorphic computing.The ability to write, store and retrieve data is at the very heart of information processing. Various techniques are employed to efficiently cope with the vast spread of speed and long term storage needs. In particular Phase Change Memories (PCMs), promise to revolutionize the field of information processing by bridging the gap between the short-term, but very quick operation of on-chip memories and the long-term, but relatively slow storage systems such as solid-state devices and hard-drives [1][2][3]. Not only can phase change materials switch in a matter of picoseconds [4-6], they are also able to retain information for very long periods of time [2,7]. In addition, they scale extremely well to the nanoscale, with present-day demonstrations of 6nm cells employing electrical switching [7,8]. Specifically Ge 2 Sb 2 Te 5 (GST) is the most commonly used alloy for such applications. By reversibly transforming the crystalline structure between amorphous and crystalline states using electrical pulses, the resistive properties of the thin film can be varied by several orders of magnitude [9]. PCMs also demonstrate a large difference in reflectivity upon phase-transition, an effect that has led to their commercial use in optical storage discs, such as DVDs and Blue-Ray discs [10].Herein, we propose a chalcogenide-based integrated photonic memory element, with the ability for sub-nanosecond reading and writing, while still retaining data for several years. We analyze the photonic architecture as illustrated in Fig.1(a), which comprises a microring resonator coupled to nanophotonic waveguides. In contrast to photonic memories and mechanical resonators [11], the photonic circuit allows for static tunability which is maintained when the control light has been switched off. We base our analysis on silicon nitride-on-insulator substrates for broadband optical applications. Silicon nitride can be used to fabricate high-quality nanophotonic components for both telecoms and visible applications [12,13]. The feeding waveguide is optimized for single mode operation at 1550nm input wavelength. Inside the ring resonator a small region of the waveguide is suspended similar to waveguides used for nanomechanical sensing [14] and opto-mechanical operation [15]. A thin film of phase change material (GST) is...

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confidence: 99%

Photonic non-volatile memories using phase change materials

Pernice¹,

Bhaskaran²

2012

Applied Physics Letters

Self Cite

153

View full text Add to dashboard Cite

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“…As described in previous work (Pernice et al 2007a) χ(ω) can be modelled by a combination of multiple Lorentzian poles and an additional Drude pole for the low frequency behavior of the material. Transforming the frequency dependent susceptibility operator into the time domain yields a system of M + 1 differential equations for a material with M Lorentzian poles and one Drude pole.…”

Section: Phenomenological Modelling Of Dispersive Behaviormentioning

confidence: 99%

“…Using a non-linear least-squares fitting algorithm we were able to describe the dispersive character of metals with high accuracy using a multi-pole Drude-Lorentzian model. The discretization of the auxiliary differential equations used in the previous article leads to a slightly harder stability limit than the traditional Yee algorithm (Pernice et al 2007a). In this paper, we suggest an alternative discretization scheme that is stable to the Courant limit.…”

Section: Introductionmentioning

confidence: 97%

“…An additional differential equation is derived and is included in the standard set of updating equations in the time domain. In previous work we have successfully include dispersive metals in the framework of the FDTD method (Pernice et al 2007a). Using a non-linear least-squares fitting algorithm we were able to describe the dispersive character of metals with high accuracy using a multi-pole Drude-Lorentzian model.…”

Section: Introductionmentioning

confidence: 99%

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An efficient multi-domain spectral algorithm for the simulation of dispersive metallic structures in the time domain

2007

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In this article, we present a multi-domain formulation of the spectral time domain algorithm for the simulation of dispersive materials. We propose a leap-frog time-stepping scheme similar to the finite-difference time domain method in order to minimize memory usage. Dispersive material behavior is modelled in the frequency domain and used in our time-domain algorithm by introducing auxiliary differential equations for the macroscopic polarization. Absorbing boundary conditions are presented that can be used with dispersive materials. The numerical investigation of structures with material parameters fitted to experimental data shows excellent agreement with theoretical calculations.

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“…In recent years, some novel dispersive models have been introduced, for example, the complex-conjugate pole-residue (CCPR) model [3], critical point (CP) model [4], modified Lorentz (m-Lo) model [5], and quadratic complex rational function (QCRF) model [6]. Some hybrid dispersion models, such as the DrudeLorentz model [7,8] and Drude-CP model [4,9], were also usually adopted. However, the introduction of these new dispersion models and their hybrid models undoubtedly challenges the versatility of the existing FDTD methods.…”

Section: Introductionmentioning

confidence: 99%

An Extended Newmark-FDTD Method for Complex Dispersive Media

Zhang

2018

International Journal of Antennas and Propagation

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Based on polarizability in the form of a complex quadratic rational function, a novel finite-difference time-domain (FDTD) approach combined with the Newmark algorithm is presented for dealing with a complex dispersive medium. In this paper, the time-stepping equation of the polarization vector is derived by applying simultaneously the Newmark algorithm to the two sides of a second-order time-domain differential equation obtained from the relation between the polarization vector and electric field intensity in the frequency domain by the inverse Fourier transform. Then, its accuracy and stability are discussed from the two aspects of theoretical analysis and numerical computation. It is observed that this method possesses the advantages of high accuracy, high stability, and a wide application scope and can thus be applied to the treatment of many complex dispersion models, including the complex conjugate pole residue model, critical point model, modified Lorentz model, and complex quadratic rational function.

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A General Framework for the Finite-Difference Time-Domain Simulation of Real Metals

Cited by 19 publications

References 24 publications

Photonic non-volatile memories using phase change materials

Photonic non-volatile memories using phase change materials

An efficient multi-domain spectral algorithm for the simulation of dispersive metallic structures in the time domain

An Extended Newmark-FDTD Method for Complex Dispersive Media

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