Voltage controlled of Electrooptic directional coupler operation

The main contributions of this master can be summarized as follows:1- A simplified algorithm is proposed to find both the propagation constant (β), coupling coefficient (C) and their changes (Δβ and ΔC) with the controlled voltage. So, the analysis of the electrooptically controlled directional coupler becomes simple with more evidence and very good agreement.2- The propagation constant without controlled voltage (βo) for BaTiO3 is the largest as expected because its ng (n2g = nx ny) is the higher. Also βo (SCE) approximately equals with βo (CPW). The value of βo decreases with the operating wavelength (λ).3- The cutoff wavelength (λcut ) decreases with the applied voltage. So the guiding waveguide becomes unguided waveguide with the applied voltage. Although we must be checked the cutoff wavelength with electrooptically controlled.4- The value of the change of propagation constant (Δβ) is calculated by using variational method (VM) and Δβ for BaTiO3 is the largest because its r33 is very high. The sign of Δβ depends upon the polarity of the controlled voltage5- The change of the propagation constants becomes electrooptically controlled. And the transferred power also electrooptically fashion.6- An empirical equations for power transferred are derived. The approximate method is checked with four electooptic materials7- The coupling coefficient with LiNbO3 is the largest. Coupling coefficient with SCE is larger than that with CPW. Also, C increases with λ but, the effect of the controlled voltage is very little..8- The effect of the controlled voltage on the coupling coefficient is very weak so, the output power of the directional coupler is affected by the change of propagation constants (i.e. by the controlled voltage).9- The electro-optic material is treated as an isotropic material. The applied electric field depends upon the controlled voltage. So, Z-cut of electro-optic material becomes the optimum case with parallel and SCE electrodes. While, Y-cut becomes the optimum case with CPW electrodes.10- The required voltages with the coplanar electrodes are calculated from the required voltages with the parallel electrodes by introducing the reduction factors (Γy for SCE and Γx for CPW).11- The optimum positions of the directional coupler waveguides are under the metal electrodes with CPW but between electrodes with SCE.12- As illustrative applications, simplification expressions for β, Δβ, C and ΔC are applied with the power divider / combiner ratios, the bandpass wavelength filter and the three waveguides directional coupler.13- The required voltage for intermediate waveguide to isolation the two lateral waveguides is evaluated.14- The output powers (P1, P2 and P3) are affected by the operating wavelength and the electrooptic materials.15- The three waveguides directional coupler as a divider or as a combiner are done. Ands several design examples are done to check the fitting curvesAlso, we present an invitation to the researchers to handle the electrooptic effect and its application and the design of IOCs because, OICs are very important in optical communication systems.