• The KIPS Transactions:PartA
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• v.12A no.2 s.92
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• pp.103-108
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• 2005

The purpose of numerical analysis is to design an effective algorithm to realize some mathematical model on computer. In general the approximate value, which is obtained from computer operation, is not the same as the real value that is given by mathematical theory. Therefore the mr estimate measuring how approximate value is near to the real value, is the most significant task to evaluate the efficiency of algorithm. The limit of an error is used for mr estimation at the most case, but the exact mr evaluation could not be expected to get for there is no way to know the real value of the given problem. Wegmann's method has been researched, which is one of the solution to derive the numerical conformal mapping. We proposed an improved method for convergency by applying a low frequency filter to the Wegmann's method. In this paper we investigate error analysis based on some mathematical theory and propose an effective method which makes us able to estimate an error if the real value is not acquired. This kind of proposed method is also proved by numerical experiment.

• Korean Journal of Optics and Photonics
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• v.14 no.5
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• pp.545-554
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• 2003

Design of the optical modulator composed of a three-waveguide coupler and CPW traveling-wave electrodes was carried out. Switching phenomena of three-waveguide couplers were analyzed by using the coupled mode theory, and the coupling-lengths of the devices were calculated by means of the FDM. CPW traveling-wave electrodes were analysed by the CMM and SOR simulation technique in order to find the conditions of phase-velocity and impedance matching. Traveling-wave modulators were fabricated on z-cut LiNbO$_3$ substrate. Ti was in-diffused in LiNbO$_3$ to make waveguides and Au electrodes were built on the waveguides by the electrolyte technique. The fabricated modulator chip was end-polished, pig-tailed and packaged in a brass mount with K-connector. The insertion loss and the switching voltage of the optical modulator were about 4㏈ and 19V, respectively. Network analyzer was used to obtain the S parameter and the corresponding RF response. From the measurement, parameters of the traveling-wave electrodes were extracted to be Z$_{c}$= 45 Ω, N$_{eff}$=2.20, and $\alpha$$_{0}$=0.055/cm√GHZ. The measured optical response R($\omega$) was compared with the theoretically estimated one, showing both responses agree well. The measurement results revealed that 3㏈ bandwidth turned out to be about 13 GHz.