23 February 2018 Novel analytical approach for strongly coupled waveguide arrays
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Coupled Mode theory and Variational methods are the most extensively used analytical methods for the study of coupled optical waveguides. In this paper we have discussed a variation of the Ritz Galerkin Variational method (RGVM) wherein the trial field is a superposition of an orthogonal basis set which in turn is generated from superposition of the individual waveguide modal fields using Gram Schmidt Orthogonalization Procedure (GSOP). The conventional coupled mode theory (CCMT), a modified coupled mode theory (MCMT) incorporating interaction terms that are neglected in CCMT, and an RGVM using orthogonal basis set (RG-GSOP) are compared for waveguide arrays of different materials. The exact effective indices values for these planar waveguide arrays are also studied. The different materials have their index-contrasts ranging between the GaAs/ AlGaAs system to Si/SiO2 system. It has been shown that the error in the effective indices values obtained from MCMT and CCMT is higher than RGVM-GSOP especially in the case of higher index-contrast. Therefore, for accurate calculations of the modal characteristics of planar waveguide arrays, even at higher index-contrasts, RGVM-GSOP is the best choice. Moreover, we obtain obviously orthogonal supermode fields and Hermitian matrix from RGVM-GSOP.
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Niharika Kohli, Niharika Kohli, Sangeeta Srivastava, Sangeeta Srivastava, Enakshi K. Sharma, Enakshi K. Sharma, } "Novel analytical approach for strongly coupled waveguide arrays", Proc. SPIE 10526, Physics and Simulation of Optoelectronic Devices XXVI, 105262K (23 February 2018); doi: 10.1117/12.2291426; https://doi.org/10.1117/12.2291426

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