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"Perkembangan teknologi informasi yang menggabungkan transmisi data, gambar, dan suara sudah sangat pesat. Teknologi ini membutuhkan bandwidth transmisi yang sangat besar. Solusi untuk memenuhi kebutuhan tersebut dapat dilakukan dengan menggunakan sistem telekomunikasi fiber optik. Salah satu metoda transmisi yang dibutuhkan untuk meningkatkan bandwidth adalah menggunakan sistem wavelength division multiplexing (WDM). Untuk tujuan tersebut berbagai disain komponen sudah dianalisa dengan berbagai metoda. Mach-Zehnder interferometer (MZI) merupakan kandidat yang paling mungkin untuk. merealisasikan maksud tersebut. Tulisan ini membahas tentang MZI yang dapat digunakan sebagai salah satu komponen pasif dalam sistem WDM. Metoda yang dipakai untuk analisa komponen tersebut adalah menggunakan coupled mode theory (CMT) untuk direksional kopler yang merupakan komponen dasar pembentuk MZI, dan analisa MZI menggunakan matrik propagasi. Parameter yang di gunakan dalam analisa ini adalah silika karena material ini digunakan untuk membuat fiber optik, sehingga kopling antara MZI dan fiber optik dapat diminimalkan. Untuk merealisasikan MZI pada rentang gelombang 1.5 gm -1.55 µm, beberapa buah MZI diparalelkan dan panjang gelombang yang dimaksud diluncurkan pada masukan (input) MZI. Dari basil analisa diperoleh kesimpulan bahwa MZI dapat digunakan sebagai komponen dasar WDM. Namun pemilihan pararnater yang tepat hares dilakukan untuk memperoleh rentang panjang gelombang pada system WDM yang diinginkan."

"ABSTRACTThe combination of the coupled mode and normal mode theories has been used to formulaic the theoretical performance represented by the coupling length and crosstalk parameters of the X-cut APE-LN SDC fabricated using the benzoic acid as the proton source, where in this case the matrix effective refractive index (MERI) method is applied for solving the symmetric and antisymmetric propagation constants of the normal modes propagating in this device. The corresponding near field method has been used to experimentally determine its crosstalk. The actual performance of this device is characterized by comparing the theoretically calculated with the experimentally determined crosstalk parameters. A software computer program has been developed in order to numerically characterize the entire characteristic and performance of the SDC under study. For the SDC under study, the best crosstalk obtained at the operating wavelength lamda =1.3 micrometer is ~0.21 dB for the interaction length L = 6 mm and the gap separation g = 5 mm. Its coupling length is ~ 1.33 mm. The propagation constant of the corresponding individual single-mode X-cut APE-LN channel waveguide making up this SDC is beta = 10.37901 micrometer, and thereby its effective refractive index is N cπ= 2.14743330. It has been shown that the fabricated SDC is very lossy. It has been deduced that its bad performance predominantly caused by the side diffusion effect, corresponding to the fabrication problem, where in this case the substrate sample has been not coated first with the buffer layer when the deposition of substrate sample with the aluminum mask was to be performed in the fabrication stages. Moreover, in this case only the simple annealing has been performed. The successive annealing process in order to reduce the coupling loss has been not applied yet. Under the assumption that the fabrication tolerances are such that the practical devices with coupling loss below 0.25 dB are feasible, the fabricated SDC under study is a 3 dB coupler. "

"Mathematical control theory for a single partial differential equation (PDE) has dominated the research literature for quite a while, new, complex, and challenging issues have recently arisen in the context of coupled, or interconnected, PDE systems. This has led to a rapidly growing interest, and many unanswered questions, within the PDE community. By concentrating on systems of hyperbolic and parabolic coupled PDEs that are nonlinear, Mathematical Control Theory of Coupled PDEs seeks to provide a mathematical theory for the solution of three main problems: well-posedness and regularity of the controlled dynamics; stabilization and stability; and optimal control for both finite and infinite horizon problems along with existence/uniqueness issues of the associated Riccati equations.Mathematical Control Theory of Coupled PDEs is based on a series of lectures that are outgrowths of recent research in the area of control theory for systems governed by coupled PDEs. The book develops new mathematical tools amenable to a rigorous analysis of related control problems and the construction of viable control algorithms. Emphasis is placed on the key role played by two interweaving features of the respective dynamical components: (1) propagation of singularities and exceptional "sharp" regularity of the traces of the solutions of the structure's hyperbolic component, and (2) analyticity of the solutions to the parabolic component of the structure, its propagation, and related analytic semigroup (singular) estimates.In addition to providing a mathematical foundation on this topic, this book is useful to engineers and professionals involved in materials science and aerospace engineering in solving fundamental theoretical control problems such as stabilization and optimal control in the context of control systems described by dynamical coupled PDEs. Modern technological applications such as smart materials, interactive systems, and intelligent controls drive further interest in this topic. Included is a wealth of examples based on the structural acoustic model. This comprises a wave equation coupled on the interface with either a plate or a shell equation. This canonical model nonetheless displays a variety of phenomena of interest."