Theoretical Analysis of Terahertz Dielectric–Loaded Graphene Waveguide

The waveguiding of terahertz surface plasmons by a GaAs strip-loaded graphene waveguide is investigated based on the effective-index method and the finite element method. Modal properties of the effective mode index, modal loss, and cut-off characteristics of higher order modes are investigated. By modulating the Fermi level, the modal properties of the fundamental mode could be adjusted. The accuracy of the effective-index method is verified by a comparison between the analytical results and numerical simulations. Besides the modal properties, the crosstalk between the adjacent waveguides, which determines the device integration density, is studied. The findings show that the effective-index method is highly valid for analyzing dielectric-loaded graphene plasmon waveguides in the terahertz region and may have potential applications in subwavelength tunable integrated photonic devices.

On characteristic behavior and flattened chromatic dispersion properties of bent photonic crystal fibers

In this paper by using modified scalar effective index method, first effective refractive index of straight and bent photonic crystal fibers are determined and then propagation parameters, such as chromatic dispersions for different structural designs of PCF, are obtained. By changing the values of affecting parameters in the bent PCF, such as different bent radius, distance between air holes $\Lambda $ and air-filling factor $d/\Lambda ,$ the chromatic dispersion is determined in terms of propagating wavelengths. The obtained results of bent PCF are compared with the results of straight PCF. The results of the present paper might be useful in designing optical devices and sensing systems.

Kefir Susu Nabati dengan Penambahan Kulit Pisang Tanduk (Musa Paradisiacal Var. Corniculata)

– Non dairy milk contains high protein and carbohydrate, low fat, and free lactose. Even more, banana peel has a potential as prebiotic because it contains 33% fructooligosaccharides (FOS). Banana peel was usually being thrown away although it still had good content. That would be a potential resource to make a non dairy kefir from it. This research aimed to know the effect on changes of fermentation parameters, the results of organoleptic tests, and the best treatment in making non dairy kefir with addition of Tanduk banana peel. The results showed that the parameters of total sugar, lactic acid, pH, TAT, viscosity, ethanol, number of yeast and LAB tests were significantly different in each sample even though not all samples were significantly different on reducing sugar. The results of organoleptic tests showed that non dairy kefir without the addition of Tanduk banana peel was the most preferred kefir with quite sweet and sour taste, not alcoholic, less sour and quite unpleasant aroma, a yellowish white color, quite thick consistency, and not bitter aftertaste. The best treatment based on the effective-index method was non dairy kefir with the addition of 5% Tanduk banana peel. Keywords: kefir, tanduk banana, non dairy milk Abstrak – Susu nabati memiliki kandungan protein dan karbohidrat yang tinggi, rendah lemak, serta tidak mengandung laktosa. Kulit pisang berpotensi sebagai prebiotik karena mengandung 33% fructooligosaccharides (FOS). Kandungan gizi kulit pisang dan susu nabati yang baik serta keinginan memanfaatkan kulit pisang Tanduk yang biasanya dibuang menjadi alasan untuk membuat kefir susu nabati dengan penambahan kulit pisang Tanduk. Tujuan penelitian ini adalah mengetahui pengaruh terhadap perubahan parameter fermentasi, hasil uji organoleptik, dan perlakuan terbaik dalam pembuatan kefir susu nabati dengan penambahan kulit pisang Tanduk. Penelitian ini mengunakan metode rancangan acak lengkap dengan variasi kadar kulit pisang Tanduk yang ditambahkan 0%, 5%, dan 10%. Hasil penelitian menunjukkan bahwa parameter gula total, asam laktat, pH, TAT, viskositas, etanol, jumlah khamir dan BAL, terdapat perbedaan signifikan pada setiap sampel, sedangkan pada parameter gula reduksi tidak semua sampel mengalami perbedaan signifikan. Hasil uji organoleptik kefir susu nabati tanpa penambahan kulit pisang Tanduk merupakan kefir yang paling disukai dengan karakteristik rasa yang cukup manis, cukup asam, tidak beralkohol, aroma kurang asam dan cukup langu, berwarna putih kekuningan, menghasilkan aftertaste yang tidak pahit, serta memiliki konsistensi cukup kental. Perlakuan terbaik berdasarkan metode indeks efektivitas adalah kefir susu nabati dengan penambahan kulit pisang Tanduk 5%. Kata kunci: kefir, pisang tanduk, susu nabati

Analysis of Filter and Waveguide Effect Based on the MIM Nanodisk with a Metallic Block

A novel and meaningful plasmonic filter based on the metal-insulator-metal (MIM) waveguides directly connected to a nanocavity with a metallic block is proposed and demonstrated numerically. By the effective index method and the resonant theory of disk-shaped nanocavity, we reveal that the resonant wavelengths can be simply tuned by adjusting the height of the block, which is in accordance with the results calculated by finite-difference time-domain (FDTD) simulations. We also rotate the metallic block to achieve two resonant modes. One mode shows a blue shift, and the other mode shows a red shift. It is shown that the proposed structure performs as a bend waveguide not a filter when the width of the block increases to hundreds of nanometers. The proposed structure will have significant potential applications in nanointegrated circuits for optical filtering and processing.