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"Sejauh ini, pendeteksian objek di dalam air dilakukan dengan teknologi sonar yang memanfaatkan gelombang suara. Namun keterbatasan kecepatan rambat suara di dalam air menjadi penghambat perkembangan sistem deteksi di bawah air. Disisi lain cahaya dapat merambat lebih cepat di dalam air, selain itu laser memiliki sifat monokromatis dan koheren sehingga laser dapat mendeteksi objek dengan jarak yang cukup jauh dan dengan akurasi tinggi. Pada Skripsi ini dilakukan eksperimen untuk mengamati karakterisasi propagasi cahaya laser dengan λ = 532 nm sebagai dasar untuk mendeteksi objek di dalam air. Eksperimen dilakukan di berbagai tingkat salinitas air, untuk mewakili berbagai jenis air di alam. Selanjutnya dilakukan eksperimen dengan membuat jaring-jaring laser serta rangkaian pendeteksi sebagai sistem pendeteksi objek asing di dalam air dengan  memanfaatkan sensor fotodioda dan ESP32. Dari hasil eksperimen didapat nilai untuk absorptivitas berkas laser semikonduktor λ = 532 nm pada air garam dengan tingkat salinitas 35 ppt adalah sebesar 0,00415 L.

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So far, underwater object detection has been carried out using sonar technology that utilizes sound waves. However, the limited speed of sound propagation in the water is an obstacle for the development of underwater detection systems. On the other side, light can travel faster in water. In addition, the laser has monochromatic and coherent properties so that the laser can detect objects at a considerable distance and with high accuracy. In this thesis, an experiment was carried out to observe the characterization of laser light propagation with λ = 532 nm as the basis for detecting objects underwater. Experiments were carried out at various levels of water salinity, to represent the different types of water in nature. Furthermore, experiments were carried out by making laser nets and detection circuits as a system for detecting foreign objects underwater by utilizing photodiode sensors and ESP32. Based on the experimental results, it was found that the absorptivity of the semiconductor laser beam λ = 532 nm in salt water with a salinity level of 35 ppt was 0.00415 L."

"ABSTRACTFor the purpose of optically cooling, trapping, detecting and accelerating Cesium atoms in a "fountain clock", semiconductor lasers with external resonator have been designed, built and tested in their spectral characteristic and their long-term frequency drift. Multiple Quantum Well lasers with AR coating on one end face and a high reflection coating on the other end face have been used which produce 50 mW at 852 nm ( single end output ). With an external grating resonator the line width was reduced to 150 KHz. Doppler emitted and saturated absorption spectra of the two Cs fine structure transitions were recorded. The saturated absorption lines (Lamb dips) were utilized as optical discriminators in order to stabilize the laser frequencies off line center as is required for optical cooling. Beat frequency measurements between two external resonator laser diodes permitted to measure the 150 KHz line width, and to observe the quality of the long-term frequency stabilization. "

"This book reviews the application of semiconductor nanocrystals also known as colloidal quantum dots (QDs) to LED lighting for indoors and outdoors as well as LED backlighting in displays, summarizing the color science of QDs for lighting and displays and presenting recent developments in QD-integrated LEDs and display research. By employing QDs in color-conversion LEDs, it is possible to simultaneously accomplish successful color rendition of the illuminated objects and a good spectral overlap between the emission spectrum of the light source and the sensitivity of the human eye at a warm white color temperature-something that is fundamentally challenging to achieve with conventional sources, such as incandescent and fluorescent lamps, and phosphor-based LEDs."

"Salah satu usaha untuk meningkatkan kapasitas transmisi dan/atau memperpanjang jarak transmisi pada komunikasi serat optik, yaitu dengan dikembangkannya diode laser yang dapat diatur panjang gelombangnya (tunable laser diode). Diode laser ini dapat dibuat dengan 2 cara, yaitu memfabrikasi langsung laser mode tunggal (single mode laser) atau laser mode jamak (multimode laser) yang digandeng dengan external tuning. Pada Tesis ini dilakukan uji coba dan analisa suatu sistem penalaan (tuning), sehingga cahaya laser menghasilkan panjang gelombang dengan lebar spektral yang sempit. Sistem ini menggunakan laser semikondulctor GaAs sebagai diode laser mode jamak yang mempunyai rentang panjang gelombang 640,7 nm and 722,08 nm dan daya maksimum 4 mW. Disamping itu sebagai external tuning digunakan kisi yang mempunyai jarak antara celala (d) = 327,762 µm ± 55,84 p.m , sedangkan antara diode laser dengan kisi, digunakan lensa sebagai kolimator. Dari hasil uji coba dan analisa menunjukkan bahwa panjang gelombang yang akan ditransmisikan dapat dipilih dengan merubah sudut kisi terhadap sumbu optic. Perubahan sudut kisi dapat dilakukan antara 0° sampai 60°, sedangkan panjang gelombangnya antara 675,86 nm dan 682,43 nm dengan lebar spektral antara 29.65 nm dan 113.10 nm.

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One way to increase transmission capacity and/or to extend transmission distance in optical fiber communication is by providing tunable laser diode. There are two ways in making each laser diode, namely, fabricating directly single mode laser or using multimode laser coupled with external tuning. In this thesis a tuning system will be measured and analysed, so that laser light produces the wavelength with narrow spectral width. This system uses GaAs laser semiconductor as multimode laser diode that has wavelength range 640.7 nm and 722.08 rim and maximum power of 4 mW. Besides grating with period of grating 327,762 p.m ± 55,84 p.m is used as external tuning, while between laser diode and grating, a lens is used as collimator. The measurement and analysis shows that the wavelength that will be transmitted can be selected by changing grating angle to optical axis. The variation of grating angle is between 0° and 60°, whereas the wavelength is between 675.53 nm and 682.43 nm with spectral width between 29.65 nm and 113.10 nm."

"Penelitian pada tesis ini di bidang divais fotonik diutamakan pada pabrikasi dan karakterisasi dari bahan dasar GaInAsP/InP untuk penguat optik dengan panjang gelombang 1,55 µm, yang tidak lain adalah sama dengan bahan dasar untuk laser semikonduktor.Pada rancang bangun penguat optik dibuat struktur lapisan yang menghasilkan moda tunggal yang terdiri dan 4 buah lapisan GaInAsP, masing-masing 2 lapisan pandu gelombang dengan panjang gelombang 1,17 pm, lapisan aktif dengan 1,55 pm, dan lapisan anti cair ulang (ACU) dengan 1,3 gm. Untuk penumbuhan dipilih lapisan pandu gelombang dengan ketebalan 0,25 gm, lapisan aktif 0,19 pm dan lapisan ACU 0,19 gm. Di tumbuhankan dengan menggunakan LPE (Liquid Phase Epitaxy) yaitu penumbuhan yang dilakukan pada saat kristal dalam keadaan fasa cair dengan teknik penumbuhan Two-Phase Solution. Bahan InP, GaAs, InAs sebagai bahan sumber ditumbuhkan diatas substrat InP, membentuk struktur lapisan DH (Double Heterostructure) instrinsik tujuh lapisan dan melalui proses lanjutan dapat dibuat menjadi penguat optik atau diode laser sernikonduktor GaInAsP/InP 1,55 µm.Struktur dasar GaInAsP/InP untuk penguat optik dibuat dengan proses penumbuhan, yang dimulai dengan menyentuhkan larutan kristal Indium pada sampel substrat, kemudian dilakukan penumbuhan lapian dengan menyentuhkan larutan kristal secara berurutan diatas sampel substrat. Proses penumbuhan dilakukan tiga tahapan, yaitu : tahapan pendahuluan, tahapan pembentukan pandu gelombang dan tahapan pembentukan struktur DH (Double Heterostucture). Ketebalan lapisan dapat diatur dengan memvariasi suhu peleburan dan waktu penumbuhan. Karakterisasi ketebalan lapisan dilakukan dengan menggunakan SEM, dan Pengukuran panjang gelombang dilakukan dengan photoluminescence, dengan cara menembakkan laser pada pennukaan sampel. Emisi pandu gelombang diterima, direkam menggunakan optical spectrum analyzer (OSA).

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This research is focused on photonic devices particularly on fabrication and characteristic of 1.55 gm GaInAsP/InP semiconductor laser materials for an optical amplifier.

The Optical amplifier was designed for a single-mode laser. This layers contains of four layers where two of them ar ,used as 1,17 p.m wave guide and the other are applied as a 1,55 µm active layer and a 1,3 gm anti melt back (AMB) layer. The layers were growth by designing 0.25 gm wave guiding layer thickness, 0,19 gm active layer thickness, and 0.19 gm AMB layer thickness. The layers was grow by LPE (Liquid Phase Epitaxy) with The Two Phase Solution growing technique. Source material InP, GaAs, InAs was grown on InP substrate, form seven layers of intrinsic DH and then via further process, these layers structure ca be made as an optical amplifier or a semiconductor laser diode of 1.55 gm GaInAsPfInP .

The basic structure was made by touching an indium crystal on a sample substrate. Then , some layers were growth by touching other crystal solution consecutively on the sample substrate. The growth process was three step of growth i.e: in the first place of growth, growth of wave guide and growth of DH. The thickness of any layers was arranged by varying the melting temperature and the growth time. The thickness characterization of the layer was carried out by SEM and the wave length measurement was executed by shooting a laser on the sample surface. The emission of the wave guides was received and recorded by an optical spectrum analyzer."