Microwave CAD circuit modeling of traveling-wave electroabsorption modulator

Lewén, R.; Irmscher, S.; Eriksson, Urban

doi:10.1109/tmtt.2003.809669

Cited by 36 publications

(10 citation statements)

References 18 publications

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Section: Resultssupporting

confidence: 64%

“…Y and Z have been extracted from the complex propagation constant and the characteristic impedance Z c computed according to the power-current definition [4]. Our numerical results are in good agreement with the experimental results in [5].To assess the effect of optical power on the electrode propagation characteristics, simulations at different optical power levels have been performed. The electro-optical model for the active layer has been extracted from the experimental results reported in [6], at the operating wavelength of 1.544 µm; uniform optical illumination has been assumed, with an optical confinement factor of 0.2 in the active layer.…”

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confidence: 62%

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Accurate simulation of travelling-wave electroabsorption modulators through a novel coupled electromagnetic and carrier-transport model

Bertazzi

Cappelluti

Bonani

et al. 2005

2005 IEEE LEOS Annual Meeting Conference Proceedings

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IntroductionExternal travelling-wave electroabsorption modulators (TW-EAMs) are suitable components for the development of high-speed fiber optic links, with potential for a wide range of functionalities, either broadband or narrowband. Despite the limited RF waveguide length, that is always electrically short (at least for microwave frequencies), the travelling-wave design significantly overcomes the bandwidth limitation inherent to the lumped approach, providing high efficiency as well as high speed. The typical TW-EAM structure exploits a p-i-n heterojunction embedded in a non-planar microwave waveguide. Being fabricated on heavily doped substrates, the transmission line exhibits high microwave losses, strongly asynchronous coupling to the optical signal, and impedance mismatch with respect to 50 Ω. Moreover, the p-i-n junction and the significant optical absorption and photocarrier generation in the intrinsic layer make the RF behavior dependent on the applied DC bias and incident lightwave, affecting the device behavior in terms of achievable extinction ratio and bandwidth. Thus, the accurate design and optimization of TW-EAMs requires large signal modeling tools, taking into account the dispersive, nonlinear behavior of the microwave and optical waveguide as well [2,1].While a purely electromagnetic (EM) approach, modeling the semiconductor as a constant conductivity medium, gives accurate results in the analysis of metal-semiconductor transmission line (e.g. it captures the slow-wave effect), this is not appropriate at all in describing the influence of DC bias or optical power typical of distributed optoelectronic devices. A rough estimate of the capacitance of reverse biased p-i-n structures can be achieved by approximating the depleted region as a dielectric; however, an accurate evaluation of this parameter as a function of bias, especially in presence of a significant concentration of photogenerated carriers, not only requires to compute the free charge profile in the depletion region, but also to account for small-signal diffusion currents, in turn requiring a direct treatment of semiconductor transport within the EM model. In this paper a novel coupled full-wave EM and carrier transport model is applied to the analysis of the RF propagation of TW-EAMs, with relevance on the effect of optical power on the microwave loss. Modeling approachIn the literature, a few examples of coupled full-wave EM and transport models have been presented so far. A very general frequency-domain coupled formulation, including nonlinearity, has been recently proposed in [3]. However, the computational complexity limits the treatment to a 1D cross-section, thus neglecting geometrical and fringing effects that may significantly affect the microwave propagation characteristics in realistic structures.In the present paper, we propose a simplified but computationally efficient finite-element approach that reduces the field-transport problem to a DC analysis followed by a guided-wave linearized problem, in which the full-wave EM...

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Section: Resultssupporting

confidence: 64%

mentioning

confidence: 62%

Accurate simulation of travelling-wave electroabsorption modulators through a novel coupled electromagnetic and carrier-transport model

Bertazzi

Cappelluti

Bonani

et al. 2005

2005 IEEE LEOS Annual Meeting Conference Proceedings

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“…Several variants of this model have been used: the parallel resistance R p is sometimes assumed to be infinite [8], and an additional capacitance, C dx , has been placed in parallel between R s and ground to distinguish between the intrinsic diode and fringe capacitances [9]. Traveling wave models [10] are more accurate, but not necessary in this case because the device length is far smaller than 1/16 of the microwave wavelength. The relative predictive powers of competing models can be evaluated using a cross-validation procedure, as will be discussed in Section 4.3, though as a general principle, fitting more parameters results in larger confidence intervals and fits that more closely follow the data.…”

Section: Measurement and Modelingmentioning

confidence: 99%

Markov chain Monte Carlo methods for statistical analysis of RF photonic devices

Piels¹,

Zibar²

2016

Opt. Express

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Abstract:The microwave reflection coefficient is commonly used to characterize the impedance of high-speed optoelectronic devices. Error and uncertainty in equivalent circuit parameters measured using this data are systematically evaluated. The commonly used nonlinear least-squares method for estimating uncertainty is shown to give unsatisfactory and incorrect results due to the nonlinear relationship between the circuit parameters and the measured data. Markov chain Monte Carlo methods are shown to provide superior results, both for individual devices and for assessing within-die variation.

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“…This could be represented by additional connections between unit cells, but accurate results were obtained without doing this. The traveling-wave impedance can be found from analytical [14] or finiteelement solvers. For many devices, including the ones considered here, traveling wave effects are not very important, but replacing it with a short can result in numerical instability.…”

Section: The Linear Modelmentioning

confidence: 99%

Nonlinear modeling of waveguide photodetectors

2013

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Abstract:A new method of simulating photodiode nonlinearities is proposed. This model includes the effects of non-uniform absorption in three dimensions, self-heating, and is compatible with circuit components defined in the frequency domain, such as transmission lines. The saturated output power and third order output intercept points of two different waveguide photodiodes are simulated, with excellent agreement between measurement and theory. The technique is then used to provide guidance for the future design of linear waveguide-based photodetectors.

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Microwave CAD circuit modeling of traveling-wave electroabsorption modulator

Cited by 36 publications

References 18 publications

Accurate simulation of travelling-wave electroabsorption modulators through a novel coupled electromagnetic and carrier-transport model

Accurate simulation of travelling-wave electroabsorption modulators through a novel coupled electromagnetic and carrier-transport model

Markov chain Monte Carlo methods for statistical analysis of RF photonic devices

Nonlinear modeling of waveguide photodetectors

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