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"This book demonstrates the implementation of an automated measuring system for very efficient measurement of chromatic dispersion, which uses a modulation phase shift method over long haul of optical single mode fiber. The authors show how a new scheme for measuring chromatic dispersion is adopted in conjunction with a tunable laser (TLS), providing the optical power at required wavelength and digital oscilloscope (DOSC) for measuring the phase difference between microwave signals from transmitter and microwave signals at the receiver. This is a novel approach for real-time chromatic dispersion in optical systems such as optical fibers. The setup used is very simple, accurate and cost effective, compared to other methods such as direct measurement, differential mode delay, polarization mode dispersion measurement and phase delay method. "

"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 ..."

"ABSTRAKDivais 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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ABSTRACTDirectional 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."

"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"

"Parallel-coupled wave-guide with symmetrical structure has interesting coupling characteristics and can be used as multiplexer/demultiplexer when certain working requirements are met. The coupling properties in the coupled wave-guide are analyzed theoretically on the basis of two mode interference effect of the propagating waves, wavelength dependence of wave-guide directional coupler is investigated in the coupling region. A rough approximation of the dependence is determined based on simplified transfer matrix multiplications followed by more detailed computer calculation using Beam Propagation method CBPMI.

By varying the dimensions of wave-guide such as width, thickness, gap, interaction length, refractive index difference and wavelength we could get different coupling properties, then the results of analysis are used to select the appropriate dimensions of multiplexer/demultiplexer that works on the range of wavelength (1.3 pm - 1.6 pm). This burned channel-type directional coupler is designed on Silicon substrate to be fabricated by sputtering technology."