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Abstrak :
ABSTRAK
Divais directional coupler dan optical switch merupakan komponen yang dibutuhkan dalam pemrosesan sinyal optik. Kemajuan teknologi wavelength division multiplexing (WDM) dan pertumbuhan lalu lintas internet yang cepat memicu banyak penelitian tentang teknologi switching optik. Galium Nitrida (GaN) merupakan material semikonduktor nitrida kelompok III yang menjadi kandidat menjanjikan untuk divais yang beroperasi pada panjang gelombang komunikasi optik. Pada penelitian ini dilakukan desain directional coupler dan optical switch menggunakan material GaN untuk panjang gelombang telekomunikasi, yaitu 1,55 um. Desain directional coupler terdiri dari pandu gelombang S-bend dan linear sedangkan desain optical switch berbasis Mach-Zehnder Interferometer yang terdiri dari dua directional coupler yang dihubungkan dengan dua lengan persegi panjang. Optimasi desain dilakukan dengan metode finite difference beam propagation method (FD-BPM) menggunakan perangkat lunak OptiBPM. Optimasi dilakukan dengan memvariasikan parameter pandu gelombang meliputi lebar, ketebalan, width gap dan coupling gap. Dari hasil simulasi ditunjukkan bahwa lebar dan tebal terbaik untuk memperoleh propagasi single mode masing-masing adalah 4 um. Selanjutnya, berdasarkan hasil optimasi ukuran pandu gelombang dilakukan desain directional coupler dan optical switch. Ditunjukan bahwa directional coupler dengan panjang 980 um dan lebar 15 um dengan width gap 7 um dan coupling gap 6 μm menghasilkan daya keluaran sebesar 91,71% dengan splitting ratio sebesar 48,83% : 48,03%, excess loss dan power imbalance berturut-turut sebesar 0,37 dB dan 0,07 dB. Tahap selanjutnya, berdasarkan lebar dan tebal pandu gelombang, dilakukan optimasi desain optical switch. Dari hasil eksperimen numerik ditunjukkan bahwa desain optical switch terbaik, memiliki panjang 6380 μm dan lebar 15 um, dengan panjang elektroda 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 optical signal processing. The progress of wavelength division multiplexing (WDM) technology and the rapid growth of internet traffic have triggered much research regarding optical switching technology. Gallium Nitride (GaN) is a III-nitride semiconductor becomes a promising candidate for devices which operate in wavelength optical communications. In this research, the design of GaN-based directional coupler and optical switch design was conducted for telecommunication wavelength at 1.55 um. The design of directional coupler consists of S-bend and linear waveguide, whereas, design of optical switch based on Mach-Zehnder Interferometer consists of two directional couplers connected by two rectangular arms. Design optimization was conducted by finite difference beam propagation method (FD-BPM) using OptiBPM software. Optimization was conducted by a varying waveguide parameter such as waveguide width, waveguide thickness, 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 result of the waveguide dimension, it was conducted a design of the directional coupler and optical switch. It was noticed that the directional coupler was 980 m long, and 15 um wide with width gap and coupling gap were 7 um and 6 μm, respectively. It generated the output power of 91.71% with the splitting ratio of 48.83 %: 48.03% while the excess loss of 0.37 dB and the power imbalances of 0.07 dB. The next step, optimization of the optical switch design was conducted based on the width and thickness of the waveguide. From the simulation result, the best design of the optical switch was 6380 μm long and 15 um wide, with the electrode length was 4500 μm. The optical switch could operate as an optical switch at = 34V with an insertion loss of 1.23 dB and an extinction ratio of 8.46 dB.

Abstrak :
Pembagi daya optik berperan penting dalam pemrosesan daya optik. Di sisi lain, galium nitrida (GaN) adalah semikonduktor yang menjanjikan untuk divais elektronik dan fotonik yang beroperasi pada panjang gelombang untuk komunikasi optik. Pada penelitian ini dilakukan desain baru pembagi daya optik 1 × 4 menggunakan material GaN. Desain dikhususkan untuk panjang gelombang telekomunikasi optik 1,55 μm. Desain yang dilakukan terdiri dari kombinasi dari tiga pencabang Y dan pandu gelombang persegi. Struktur pencabang Y di sisi masukan digunakan untuk membagi daya optik menjadi dua, sedangkan dua struktur lainnya untuk menghasilkan keluaran yang terbagi menjadi empat. Pandu gelombang persegi terkopel berfungsi untuk memperlebar jarak antara keluaran pencabang Y pertama. Optimasi desain dilakukan menggunakan beam propagation method (BPM). Optimasi dilakukan dengan memvariasikan lebar dan tebal pandu gelombang, sudut pemisah, panjang pandu gelombang persegi terkopel, dan jarak antara pandu gelombang persegi terkopel (coupling gap). Hasil eksperimen numerik menunjukkan bahwa ukuran pandu gelombang persegi optimal untuk mendukung propagasi moda tunggal adalah: lebar 4 μm dan tebal 4 μm. Ditunjukkan pula bahwa sudut pemisah optimal pencabang Y adalah sebesar 1,9 ̊. Untuk bagian pandu gelombang persegi terkopel, panjang optimal untuk ketiga pandu gelombang persegi berturut-turut adalah 400 μm, 530 μm, dan 1870 μm, dengan coupling gap 1 μm. Berdasarkan hasil optimasi, desain yang dilakukan menghasilkan excess loss sebesar 0,096 dB dan imbalance sebesar 0,06 dB. Ditunjukkan pula bahwa pada rentang C-band (1,53 μm hingga 1,565 μm), nilai terendah excess loss dan imbalance berturut- turut sebesar 0,09 dB dan 0,02 dB, serta nilai tertinggi berturut-turut sebesar 0,11 dB dan 0,07 dB. ......Gallium nitride (GaN) semiconductor is a promising candidate for electronic and photonic devices operating at a wavelength for optical communications. Optical power divider as one of the passive components in optical communications is widely used. In this research, a novel 1 × 4 optical power divider using GaN semiconductor on sapphire was designed. The design was focused on optical telecommunication applications at the wavelength of 1.55 μm. The proposed design consists of a combination of three sets of Y-branch structures and rectangular waveguides coupling. The Y-branch structure at the input side was used to split the optical power into two beams while the other two Y-branch structures at the output side split it into four output beams. Rectangular waveguides coupling was designed to widen the splitting angle of the Y-branch structure at the input side. The design optimization was conducted by using the beam propagation method (BPM). The waveguide width and thickness, splitting angle of the Y-branch structure, the length of the rectangular waveguide for coupling, and coupling gap was optimized. The results of the numerical experiments showed that the waveguide was optimum to support single-mode propagation for width and thickness of 4 μm and 4 μm, respectively. It is also shown that the splitting angle for the Y-branches structure was optimum at 1.9 ̊. For the coupling section, the optimal length of the three rectangular waveguides were 400 μm, 530 μm, and 1870 μm, respectively, with a coupling gap of 1 μm. Based on the optimization results, the proposed design divided the optical power into four output beams with an excess loss of 0.096 dB and an imbalance of 0.06 dB. The performance of the design was also investigated through the C-band range (1.53 until 1.565 μm) which gave the proposed design the lowest excess loss and imbalance of 0.09 dB and 0.02 dB, respectively with the highest excess loss and imbalance of 0.11 dB and 0.07 dB.

Abstrak :
ABSTRACT
A good justification for gallium nitride on silicon is a potential for optoelectronic integrated circuits, and its low cost has stimulated the growth of GaN on large size wafers. The application interest for GaN/Si is power electronics. This current work focuses on characterization optical, electro-optical, and microstructural and simulation design of GaN/Si channel waveguide. For the characterization of GaN microstructure, we use SEM, TEM, AFM, and XRD to observe layer thickness, material structure, material roughness, and crystalline quality of materials. Using the guided wave prism coupling technique, we have fully established the index dispersion and, thickness of GaN at room temperature, as well as its surface roughness based on AFM characterization. Futhermore, the thermal dependence of GaN at ordinary and extraordinary refractive indices are determined to be at 1.227 10-5/ K and 1.77 10-5/ K, respectively. The thermal dependence of GaN shows better value than GaAs at the wavelength range of 0.4 - 1.5 m. It has a slightly low-temperature dependence. Results demonstrate that excellent waveguide properties of GaN on silicon with an optical propagation loss of GaN/Si at 633 nm is 2.58 dB/cm, which is higher than the propagation loss of GaN/sapphire at around 1.34 dB/cm. The roughness of GaN/Sapphire and GaN/Si samples have been identified at the range 1.6 - 5.2 nm and 9.6 - 13 nm, respectively. The birefringence of GaN/Si is negative within the range of -0.16 x10-2 to -6.06x10-2. This negative value means that the polarization of the wave is parallel to the optical axis. Electrooptic constants r13 = 1.01 pm/V and r33 = 1.67 pm/V are higher than those obtained for III-V GaAs semiconductors. We compared the results on Si with those on sapphire. Based on a numerical simulation using OptiBPM, the design result has single mode output with 1 m thickness layer of SiO2 at the planar waveguide design, while the channel waveguide design has 1 m thickness layer of GaN. The simulated result that the maximum power output approximately 50- 58 at the plannar and rib waveguide design.

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ABSTRAK
A good justification for gallium nitride on silicon is a potential for optoelectronic integrated circuits, and its low cost has stimulated the growth of GaN on large size wafers. The application interest for GaN Si is power electronics. This current work focuses on characterization optical, electro optical, and microstructural and simulation design of GaN Si channel waveguide. For the characterization of GaN microstructure, we use SEM, TEM, AFM, and XRD to observe layer thickness, material structure, material roughness, and crystalline quality of materials. Using the guided wave prism coupling technique, we have fully established the index dispersion and, thickness of GaN at room temperature, as well as its surface roughness based on AFM characterization. Futhermore, the thermal dependence of GaN at ordinary and extraordinary refractive indices are determined to be at 1.227 10 5 K and 1.77 10 5 K, respectively. The thermal dependence of GaN shows better value than GaAs at the wavelength range of 0.4 1.5 m. It has a slightly low temperature dependence. Results demonstrate that excellent waveguide properties of GaN on silicon with an optical propagation loss of GaN Si at 633 nm is 2.58 dB cm, which is higher than the propagation loss of GaN sapphire at around 1.34 dB cm. The roughness of GaN Sapphire and GaN Si samples have been identified at the range 1.6 5.2 nm and 9.6 13 nm, respectively. The birefringence of GaN Si is negative within the range of 0.16 x10 2 to 6.06x10 2. This negative value means that the polarization of the wave is parallel to the optical axis. Electrooptic constants r13 1.01 pm V and r33 1.67 pm V are higher than those obtained for III V GaAs semiconductors. We compared the results on Si with those on sapphire. Based on a numerical simulation using OptiBPM, the design result has single mode output with 1 m thickness layer of SiO2 at the planar waveguide design, while the channel waveguide design has 1 m thickness layer of GaN. The simulated result that the maximum power output approximately 50 58 at the plannar and rib waveguide design.

Abstrak :
Recently, gallium nitride (GaN) material has attracted the attention of researchers as a candidate for third generation semiconductor material for optical telecommunication applications. In this research, a 2x2 multimode interference optical power splitter (MMI) based on a waveguide and ridge structure is proposed using gallium nitride material on a silicon (GaN/Si) substrate for optical telecommunication applications. The design optimization carried out resulted in two optical power splitter designs based on rib (design A) and ridge (design D) waveguide. Based on the simulation using the eigenmode expansion method (EME) algorithm, design A has an optimal dimension of 15 m 212 m with an insertion loss of 0.085 dB, power balancing of 0.007 dB, C-band (1530 nm – 1565 nm) broadband bandwidth of 0.140 dB, and fabrication tolerances for width and length are ± 0.3 m and ± 0.5 m, respectively. Meanwhile, design D has optimal dimensions of 15 m 214 m with insertion loss of 0.036 dB, power balancing of 0.017 dB, C-band broadband bandwidth of 0.088 dB, and fabrication tolerances for width and length respectively. of ± 0.3 m and ± 0.5 m

Abstrak :
We propose a simple design of 1×3 optical power splitter which uses gallium nitride (GaN) on sapphire. The design consists of widely used large cross section input rib waveguide, a rectangular multimode interference (MMI) structure, and three-branch rib waveguides. The MMI structure is selected since their attractive performances, such as compactness, low excess loss, wide bandwidth and ease to fabricate. The power splitter is designed for the third telecommunication window, i.e., l = 1.55 µm. Optimization of the geometrical structure parameters for the design is conducted theoretically utilizing 3D FD-BPM method. It is found that the power splitter exhibits excess loss of 0.46 dB and imbalanced of 0.001 dB at l = 1.55 µm for

Abstrak :
Skripsi ini membahas tentang disain 3 dB Y-junction Power Splitter berbasis GaN/Al2O3 (Sapphire) untuk konfigurasi rib dan ridge waveguide. Disain dilakukan menggunakan perangkat lunak OptiBPM 12 free trial. Dari hasil simulasi dengan kriteria single mode ditunjukan bahwa Y-junction Power Splitter terbaik, yaitu low loss dan distribusi medan optik yang uniform, diperoleh saat sudut antara dua cabang 0,1o, pada posisi pandu gelombang 0,8 μm di atas sapphire (untuk rib waveguide) dan 0,55 μm di atas sapphire (untuk ridge waveguide), untuk lebar dan ketebalan pandu gelombang berturut-turut 3,1 μm dan >0,8 μm, ketebalan buffer layer 0,55 μm, serta indeks bias dan ketebalan material cladding sebesar 2,12 dan 8,8 μm. ...... In this final project, I'm designing GaN/Al2O3 (Sapphire) based 3 dB Y-junction Power Splitter. There are two configurations used in the simulation, which are rib waveguide and ridge waveguide. Based on the data acquired for single mode criteria, the optimal design, which is low loss and uniform optical distribution, is achieved by adjusting the angle of Y-junction to 0.1o with the position of waveguide is 0.8 μm above the sapphire (rib waveguide) and 0.55 μm above the sapphire (ridge waveguide) for the width and thickness of waveguide consecutively are 3.1 μm and more than 0.8 μm, the thickness of buffer layer used is 0.55 μm while the refractive index and the thickness of cladding used are 2.12 and 8.8 μm.

Abstrak :
ABSTRAK Kemajuan teknologi telah mendorong pengembangan material dasar semikonduktor. Beberapa dekade terakhir material Galium Nitrida telah menarik para peneliti untuk dikembangkan karena memiliki beberapa kelebihan, antara lain stabil terhadap suhu yang tinggi, memiliki tingkat penumbuhan epitaksi yang tinggi, konsumsi daya yang rendah dan memiliki celah pita langsung yang tinggi. Hingga saat ini, penelitian terkait pemanfaatan material GaN sebagai divais fotonik aktif telah banyak dilakukan, seperti LED, dioda laser dan detektor. Namun riset material GaN pada divais fotonik pasif, yakni divais berbasis pandu gelombang hingga kini masih sangat minim ditekuni oleh para peneliti. Termotivasi oleh hal tersebut, pada skripsi ini dilakukan desain 1 x 2 optical power divider baik dengan memanfaatkan pandu gelombang linier paralel maupun kombinasi pandu gelombang linier paralel dengan struktur S-bend. Terdapat dua konfigurasi pandu gelombang linier paralel yang didesain, yaitu dua pandu gelombang (directional coupler) dan tiga pandu gelombang (three-guide coupler); keduanya memanfaatkan fenomena coupled mode. Optimasi desain dilakukan dengan metode Finite Difference Beam Propagation Method (FD-BPM). Parameter yang dioptimasi adalah lebar dan tebal pandu gelombang, coupling gap, coupling length dan lebar struktur S-bend. Desain ini dioptimasi untuk beroperasi pada panjang gelombang telekomunikasi, yaitu 1,55 μm. Dari hasil optimasi ditunjukkan bahwa lebar dan tebal terbaik untuk memperoleh propagasi single mode masing-masing adalah sebesar 5 μm. Selanjutnya berdasarkan hasil optimasi lebar dan tebal pandu gelombang, ditentukan desain 1 x 2 optical power divider dengan konfigurasi dua dan tiga pandu gelombang linier paralel. Untuk konfigurasi dengan dua pandu gelombang linier paralel didapatkan hasil terbaik dengan coupling gap 7 μm dan coupling length 700 μm; sedangkan dengan konfigurasi tiga pandu gelombang linier paralel didapatkan hasil terbaik dengan coupling gap 7 μm dan coupling length 1000 μm. Dari hasil optimasi 1 x 2 optical power divider berbasis pandu gelombang linier, dilakukan optimasi desain berbasis kombinasi pandu gelombang linier paralel dan struktur S-bend. Dari hasil optimasi dan perbandingan diperoleh bahwa desain 1 x 2 optical power divider berbasis kombinasi pandu gelombang linier dan S-bend yang terbaik adalah dengan konfigurasi tiga pandu gelombang linier paralel dengan coupling gap 7 μm, coupling length 1000 μm; ukuran lebar dan tebal S-bend berturut-turut sebesar 5 μm dan lebar 6 μm. 1 x 2 optical power divider hasil desain ini mampu beroperasi menghasilkan daya keluaran relatif sebesar 93,192 % dengan coupling ratio mendekati ideal 50:50, excess loss 0,3062 dB dan power imbalance mendekati 0 dB.

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ABSTRACT Technological advancements have encouraged the development of semiconductor materials. In the past few decades, Gallium Nitride material has attracted many researchers due to its advantages, such as high-temperature stability, high epitaxial growth rates, low power consumption, and high direct bandgap. Until now, studies related to the use of GaN material as active photonic devices have been carried out, such as LEDs, laser diodes and detectors. However, research on GaN material on passive photonic devices, namely waveguide-based devices, has been very little. This condition motivated us to design 1 x 2 optical power divider using both parallel linear waveguides and parallel linear waveguide combinations with the S-bend structure. Two parallel linear waveguide configurations were designed, namely two waveguides (directional coupler) and three waveguides (three-guide coupler); both of them make use of the coupled mode phenomena. Design optimization was conducted using the Finite Difference Beam Propagation Method (FD-BPM) method. The waveguide parameters optimized were width and thickness, coupling gap, coupling length and width of the S-bend structure. This design was optimized to operate at telecommunications wavelengths, 1.55 μm. The results showed that the best width and thickness for each single-mode propagation were 5 μm. Furthermore, based on the results of the optimization of the width and thickness of the waveguide, the design of 1 x 2 optical power divider was optimized with two and three parallel linear waveguide configurations. For a configuration with two linear waveguides, the best results were achieved with coupling gap 7 μm and coupling length 700 μm; whereas with the configuration of three parallel linear waveguides, the best results obtained with a coupling gap 7 μm and coupling length 1000 μm. Next based on the optimization 1 x 2 optical power divider using linear waveguides, design optimization was conducted for a combination of parallel linear waveguides and S-bend structures. The results showed that the best design of 1 x 2 optical power divider was achieved by using three parallel linear waveguides and S-bend structures with coupling gap 7 μm, coupling length 1000 μm; the width and thickness of S-bend were 5 μm and 6 µm wide respectively. The proposed design gave the relative output power of 93.192% with an almost ideal coupling ratio 50:50; excess loss of 0.3062 dB and power imbalance close to 0 dB.

Abstrak :
This thesis describes the device physics of GaN-based laser diodes, together with recent efforts to achieve longer emission wavelengths and short-pulse emission. Experimental and theoretical approaches are employed to address the individual device properties and optimize the laser diodes toward the requirements of specific applications.