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"In line with the increasing need for higher performance for optical and photonic telecommunications equipment at the lowest possible cost, the need for supporting equipment is also increasing. One of these components is an optical power splitter. This component is needed in network systems to distribute light to other components, especially multi-channel optical power separators to support larger network systems. One of the materials developed as a photonic device material from group III-nitride is gallium nitride (GaN). Besides having a large direct bandgap (3.4eV), GaN also has good resistance to temperature changes. Thus, GaN-based power splitters are an interesting research topic to obtain more improvements, innovations and inventions for future demands. In this research, an optical power splitter design is proposed based on the 1 × 8 multimode interference (MMI) structure. The design has been carried out theoretically using 3D FD-OptiBPM on GaN material. Structural modeling using 300 nm AlN and 200 nm AlGaN as a buffer layer on a sapphire substrate material. Numerical experiments were carried out at the optical telecommunications wavelength at = 1.55 m with the effective refractive index of the coating used =2.279±0.001 and =2.316±0.001. The results showed that the optimum width and thickness of the rectangular input channel and taper-shaped output channel was 4 m, and only supported single mode propagation. From the experimental simulation results, it is shown that the MMI-based optical power separator with a total length of 2010 m and a width of 85 m is the best result. It is also shown that the output power is split almost uniformly into eight output channels with a relative output power of 0.96 on the output channel, 0.28 dB of excess loss and 0.28 dB of power imbalance. 13 dB. "

"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"

"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.

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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."

"Inthis paper, we propose a 1x2 and 1x4 optical power splitter from 1500 to 1600 nm based on multimode interference (MMI) structure with tapered input and output waveguides. The results obtained from modal propagation analysis (MPA) and beam propagation method (BPM) show better performance of the tapered structures than that of without taper in term of the power imbalance and insertion loss by 44.94% and 32.50% for 1x2 and 21.18 and 73.03% for 1x4 respectively. These suggest that the proposed structures may be a better candidate foe efficient wideband optical signal processing and communication."

"Filter optik add/drop merupakan komponen yang penting dalam sistem wavelength division multiplexing (WDM). Microring resonator merupakan struktur fotonika yang umum digunakan untuk aplikasi filter add/drop. Popularitas microring resonator sebagai filter add/drop didasari karakteristiknya yang mampu menghasilkan Q-factor tinggi dalam dimensi yang kecil serta selektivitas panjang gelombang yang tinggi. Di sisi lain galium nitrida (GaN) adalah semikonduktor yang memiliki karakteristik yang menjanjikan untuk aplikasi divais optolektronika berkecepatan tinggi dan pada kondisi lingkungan ekstrim.Pada tesis ini dilakukan desain filter optik add/drop berbasis struktur microring resonator menggunakan material GaN. Filter ini dirancang untuk beroperasi pada rentang panjang gelombang C-band (1530 - 1565 nm), khususnya pada panjang gelombang 1550 nm. Struktur filter ini terdiri dari pandu gelombang berbentuk racetrack yang terkopel ke dua pandu gelombang bus. Proses optimasi desain dilakukan dengan metode finite difference time domain (FDTD) menggunakan perangkat lunak Lumerical MODE. Parameter yang dioptimalisasikan meliputi dimensi pandu gelombang, celah udara, panjang coupler, dan panjang rongga resonansi.Hasil optimalisasi menunjukkan bahwa dimensi pandu gelombang yang optimal untuk aplikasi filter microring resonator adalah . Selanjutnya, hasil simulasi filter menunjukkan bahwa parameter microring resonator yang optimal adalah: lebar celah udara 100 nm; panjang coupler ; dan panjang rongga resonansi . Struktur ini memiliki FSR sebesar 25,3 nm; FWHM sebesar 0,2 nm (25 GHz); on-off ratio sebesar 35 dB; serta transmisi resonansi pada through port dan drop port berturut-turut sebesar -16 dB dan -1,4 dB dengan panjang gelombang resonansi 1550 nm.Di samping itu untuk menghasilkan flatness (kedataran) pada pass-band dilakukan juga simulasi dan analisa struktur double microring resonator dengan parameter optimal yang didapatkan dari simulasi sebelumnya. Jarak antara microring divariasikan untuk mencari nilai optimal. Hasil simulasi menunjukkan bahwa dengan jarak antara microring sebesar 275 nm, didapatkan spektrum transmisi drop port yang lebih datar dibandingkan struktur single microring pada rentang panjang gelombang 1550,4 -1550,8 nm dengan nilai transmisi resonansi sebesar -4 dB

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An optical add/drop filter is a crucial component for wavelength division multiplexing (WDM) systems. A Microring resonator is a photonics structure that is widely used as an add/drop filter. The popularity of microring resonators as an add/drop filter is due to their ability to achieve a high Q-factor with small footprints and wavelength selectivity. On the other hand, gallium nitride (GaN) have favorable characteristics for application in extreme conditions and high-speed optoelectronic devices.

In this thesis, the design of an optical add/drop filter based on a microring resonator with GaN material was conducted. This filter is designed to operate within the C-band (1530 – 1565 nm) wavelength range, especially at 1550 nm. The filter structure consists of a racetrack-shaped waveguide coupled into two bus waveguides. The optimization process was conducted by the finite difference time domain (FDTD) method using Lumerical MODE software. The parameters that were optimized include waveguide dimensions, air gap, coupler length, and cavity length.

The optimization results showed that the optimum waveguide dimensions are . Next, the simulation results showed that the optimum microring resonator parameters are: an air gap of 100 nm; coupler length of ; and cavity length of . This structure has an FSR of 25.3 nm; FWHM of 0.2 nm (25 GHz); an on-off ratio of 35 dB; and a through port and a drop port resonance transmission of -16 dB and -1.4 dB with a resonant wavelength of 1550 nm.

Aside from that, in order to achieve flatness on pass-band, simulation and analysis of double microring resonator structure were also conducted using the previously obtained optimum parameter. The distance between the two microrings was varied to find the optimum value. Simulation results showed that with a distance of 275 nm, a flatter drop port transmission spectrum than the single microring configuration within a 1550,4 nm – 1550,8 nm with a resonance transmission value of -4 dB was obtained"

"ABSTRAKKemajuan 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

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."

"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 ..."

"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"