ABSTRAK
Divais directional coupler dan optical switch merupakan komponen yangdibutuhkan dalam pemrosesan sinyal optik. Kemajuan teknologi wavelength divisionmultiplexing (WDM) dan pertumbuhan lalu lintas internet yang cepat memicu banyakpenelitian tentang teknologi switching optik. Galium Nitrida (GaN) merupakan materialsemikonduktor nitrida kelompok III yang menjadi kandidat menjanjikan untuk divaisyang beroperasi pada panjang gelombang komunikasi optik.Pada penelitian ini dilakukan desain directional coupler dan optical switchmenggunakan material GaN untuk panjang gelombang telekomunikasi, yaitu 1,55 um.Desain directional coupler terdiri dari pandu gelombang S-bend dan linear sedangkandesain optical switch berbasis Mach-Zehnder Interferometer yang terdiri dari duadirectional coupler yang dihubungkan dengan dua lengan persegi panjang. Optimasidesain dilakukan dengan metode finite difference beam propagation method (FD-BPM)menggunakan perangkat lunak OptiBPM. Optimasi dilakukan dengan memvariasikanparameter pandu gelombang meliputi lebar, ketebalan, width gap dan coupling gap.Dari hasil simulasi ditunjukkan bahwa lebar dan tebal terbaik untuk memperolehpropagasi single mode masing-masing adalah 4 um. Selanjutnya, berdasarkan hasiloptimasi ukuran pandu gelombang dilakukan desain directional coupler dan opticalswitch. Ditunjukan bahwa directional coupler dengan panjang 980 um dan lebar 15 umdengan width gap 7 um dan coupling gap 6 μm menghasilkan daya keluaran sebesar91,71% dengan splitting ratio sebesar 48,83% : 48,03%, excess loss dan power imbalanceberturut-turut sebesar 0,37 dB dan 0,07 dB.Tahap selanjutnya, berdasarkan lebar dan tebal pandu gelombang, dilakukanoptimasi desain optical switch. Dari hasil eksperimen numerik ditunjukkan bahwa desainoptical switch terbaik, memiliki panjang 6380 μm dan lebar 15 um, dengan panjangelektroda sebesar 4500 μm. Optical switch mampu beroperasi sebagai switch pada
 =34 V dengan insertion loss dan extinction ratio berturut-turut sebesar 1,23 dB dan 8,46 dB

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ABSTRACT
Directional coupler and optical switches are the components needed in opticalsignal processing. The progress of wavelength division multiplexing (WDM) technologyand the rapid growth of internet traffic have triggered much research regarding opticalswitching technology. Gallium Nitride (GaN) is a III-nitride semiconductor becomes apromising candidate for devices which operate in wavelength optical communications.In this research, the design of GaN-based directional coupler and optical switchdesign was conducted for telecommunication wavelength at 1.55 um. The design ofdirectional coupler consists of S-bend and linear waveguide, whereas, design of opticalswitch based on Mach-Zehnder Interferometer consists of two directional couplersconnected by two rectangular arms. Design optimization was conducted by finitedifference beam propagation method (FD-BPM) using OptiBPM software. Optimizationwas conducted by a varying waveguide parameter such as waveguide width, waveguidethickness, width gap and coupling gap.From the simulation results, the best of width and thickness were 4 um and 4 um,respectively, for support single-mode propagation. Next, based on the optimization resultof the waveguide dimension, it was conducted a design of the directional coupler andoptical switch. It was noticed that the directional coupler was 980 m long, and 15 umwide with width gap and coupling gap were 7 um and 6 μm, respectively. It generatedthe output power of 91.71% with the splitting ratio of 48.83 %: 48.03% while the excessloss of 0.37 dB and the power imbalances of 0.07 dB.The next step, optimization of the optical switch design was conducted based onthe width and thickness of the waveguide. From the simulation result, the best design ofthe optical switch was 6380 μm long and 15 um wide, with the electrode length was 4500μm. The optical switch could operate as an optical switch at = 34V with an insertionloss of 1.23 dB and an extinction ratio of 8.46 dB.