• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.185-188
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• 1998

A three-waveguide coupler consisted of a central guide and two side guides is theoretically explored by using modal transmission-line theory. The numerical results reveal that the coupling length Lc is different from that calculated by coupled-mode theory and the difference increases gradually as the guiding modes increase.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.917-920
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• 1999

Modal transmission-line theory is described for guided electron waves in quantum-well structures. To demonstrate the validity and usefulness of this approach, we evaluate the propagation characteristics and the coupling properties of electron guiding couplers consisting of double quantum-wells (DQWs).

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.4
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• pp.27-33
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• 2003

Circular Distributed-feedback (DFB) guiding structures can be incorporated in most of the semiconductor laser devices because of the frequency-selective property applicable as an optical filter in optical communications. In this paper, we present a novel and simple modal transmission-line theory (MTLT) using Floquet-Babinet's principle to analyze the optical filtering characteristics of Bragg gratings with cylindrical profile. The numerical results reveal that this method offers a simple and convenient algorithm to analyze the filtering characteristics of circular DFB configurations as well as is extended conveniently to evaluate the guiding problems of circular multi-layered periodic structures.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.2
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• pp.147-152
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• 2014

A longitudinal modal transmission-line theory(L-MTLT) to analyze the static and dynamic behavior of two-section distributed feedback (DFB) lasers is used. The characteristic impedance and equivalent propagation constant of DFB structure with active layer are derived from L-MTLT. A two-section DFB laser is analogous to a transmission-line network, in which each section is described by transmission-line block corresponding to the equivalent factors. The longitudinal resonant condition of DFB laser based on equivalent transmission-line network is used to reformulate the rate equations so that static and dynamic behavior of two-section DFB lasers with active layer is demonstrated and analyzed accurately.

• Proceedings of the IEEK Conference
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• 2000.07b
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• pp.945-948
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• 2000

The coupling properties of supermodes guided by grating-assisted directional couplers (GADCs) can be phrased in rigorous modal theory. Such a modal solution for TE modes expressed by simple electrical transmission-line networks is utilized to analyze the power distribution of GADCS with three guiding channels. In particular, the modal transmission-line theory can serve as a template for computational algorithms that systematically evaluate the coupling efficiency that are not readily obtained by other methods.

• International Journal of Internet, Broadcasting and Communication
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• v.4 no.2
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• pp.22-27
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• 2012

The design characteristics of circular vertical-cavity surface-emitting lasers are studied by using a newly developed equivalent network. Optical parameters, such as the stop-band or the reflectivity of periodic mirrors and the resonance wavelength, are explored for the design of these structures. To evaluate the differential quantum efficiency and the threshold current density, a transverse resonance condition of modal transmission-line theory is also utilized. This approach dramatically reduces the computational time as well as gives an explicit insight to explore the optical characteristics of circular vertical-cavity surface-emitting lasers (VCSELs).

• Journal of the Optical Society of Korea
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• v.8 no.4
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• pp.149-155
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• 2004

Newly developed modal transmission-line theory(MTLT) is used to analyze rigorously the optical power distribution in grating-assisted directional couplers(GADCs) with three guiding channels. By defining a novel coupling efficiency ${\eta}$ amenable to the rigorous analytical solutions of modal transmission-line theory, we explicitly evaluate the power coupling and distribution of TM modes. The results reveal that the incident power is sensitively partitioned through three output channels in terms of such grating parameters as the grating period, the duty cycle, and the operating wavelength.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.359-362
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• 1998

The electromagnetic properties of leaky-waves guided by metal-strip grating configurations can be phrased in rigorous modal theory. Such a modal solution expressed by simple electrical transmissionline networks is utilized to analyze the leakage and filtering characteristics of metal-strip gratings. In particular, the modal transmission-line theory can serve as a template for computational algorithms that systematically evaluate the radiation effects that are not readily obtained by other methods.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.3
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• pp.173-178
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• 2019

To analyze the diffraction properties of optical signals by periodic blazed 2D diffraction gratings, Toeplitz dielectric tensor is first defined and formulated by 2D spatial Fourier expansions associated with asymmetric blazed grating profile. The characteristic modes in each layer is then based on eigenvalue problem, and the complete solution is found rigorously in terms of modal transmission-line theory (MTLT) to address the pertinent boundary-value problems. Toeplitz matrix of symmetric and sawtooth profiles is derived from that of asymmetric blazed grating profile, and the diffraction properties for each profile are numerically simulated. The numerical results reveal that the asymmetric and symmetric profiles behave as anti-reflection GMR filter while the sawtooth profile works better as anti-transmission one rather than anti-reflection filter.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.1
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• pp.247-252
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• 2019

The diffraction properties of optical signals by multi-layered periodic structures is formulated in two-dimensional space by using Fourier expansions associated with basic grating profile. The fields in each layer are then expressed in terms of characteristic modes, and the complete solution is found rigorously by using a modal transmission-line theory(MTLT) to address the pertinent boundary-value problems. Such an approach can treat periodic arbitrary gratings containing arbitrarily shaped dielectric components, which may generally have optical properties along directions that are parallel or perpendicular to the multi-layers. This paper illustrates the present approach by comparing our numerical results with data reported in the past for simple periodic circular 2D structures. In addition, this proposed theory can apply easily for more complex configurations, which include multiple periodic regions with several possible canonic shapes and high dielectric constants.