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"Development of optical fiber communication system is mainly due to the progressive influence of optical source. Laser diode as optical source in optical transmission system is of great attention because laser diode produces coherent monochromatic-light. Furthermore, laser diode has a high quantum efficiency, can be modulated at a very high speed, has small size and compact. The application of such optical source is also wide, ranging from optical signal communication to radar optics. Therefore, laser diode is considered to be a key component in optoelectronic system. In this study, an experimental model of analog optical transmission system with laser diode as optical source at wavelength of 0.79 pm has been designed and constructed. The design and construction include optical and electronic circuits. Design description at the wavelength used in this study is briefly described. The characteristics of the system was evaluated by measuring the frequency responds of photo detector, the transmission bandwidth and the loss of the system. The result shows that the frequency responds of the photo detector limits the transmission bandwidth of the whole system. On the other hand, by the use of the selfoc lens for coupling laser diode to fiber line, a coupling efficiency as high Es 55 % has been achieved. Based on the evaluation on the result obtained for the experimental model the practical applicability of the system is pointed out."

"Dalam tesis ini dilakukan simulasi komputer untuk mempelajari efek pre-chirping pada perambatan dan interaksi soliton di dalam single mode dispersion shifted fiber. Simulasi dilakukan dengan cara menyelesaikan Non-Linear Schrodinger Equation (NLSE), yaitu suatu persamaan yang memodelkan perambatan pulsa optik di dalam non-linier fiber optik Solusi NLSE diperoleh secara numerik dengan Symmetrized Split Step Fouried Method (SSSFM). Penyelesaian SSSFM dilakukan dengan membuat program menggunakan software MatLab 7.0. Program simulasi SSSFM yang dibuat akurasinya diuji dengan membandingkannya dengan solusi eksak dari perambatan soliton di dalam lossless fiber optik.Hasil perbandingan menunjukan SSSFM memberikan hasil yang sangat akurat dalam menyelesaikan NLSE, dimana Normalized Square Deviation (NSD)-nya sangat kecil (dalam circle -8 sampai -9) dibandingkan dengan solusi eksak NLSE. Loss pada fiber dikompensasi dengan dilakukan pengamatan secara periodik dan metode pre-emphasis.Dari hasil-hasil dan evaluasi yang diperoleh maka didapatkan bahwa efek pre-chirping menimbulkan efek merugikan bagi perambatan dan interaksi soliton di dalam single mode dispersion skied fiber. Sehingga untuk menghasilkan sistem komunikasi soliton yang baik maka pulsa input sebaiknya bebas chirp, atau memiliki nilai chirp yang rendah dan bernilai positif.

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In this thesis, computer simulation is made to study pre-chirfing effects on propagation and soliton interaction in single mode dispersion shifted fiber. The Non-Linear Schrodinger Equation (NLSE), the equation that governs propagation of optical pulse envelope in non-linear fiber optics, is solved numerically by Symmetrized Split Step Fouried Method (SSSFM) using, MatLab 7.0.

The validity of SSSFM in determined by comparing with exact solution of NLSE, that show SSSFM gives accurate result with Normalized Square Deviation (NSD) is in order -S to -9. Fiber loss is compensated by amplifies' which is placed periodically along t he fiber link and pre-emphasis method.

From the results and evaluation, it is shown that pre-chirping effects degrade the performance of propagation and soliton interaction in single mode dispersion shifted fiber, so to achieve a good performance of soliton communication system, the input pulse is chirp free, or minimized and have positive value."

"Pengguna komunikasi memerlukan sistem komunikasi yang efektif digunakan kapanpun, dimanapun dan di semua media yang diinginkan. Sistem komunikasi tersebut lebih efektif dilakukan oleh jaringan tanpa kabel dengan memanfaatkan teknologi radio over fiber (ROF). Sistem jaringan ROF yang banyak digunakan adalah jaringan RF yang menggunakan serat optik mode tunggal. Untuk itu diperlukan divais laser semikonduktor yang mempunyai noise dan distorsi rendah pada frekuensi tinggi. Pada penelitian ini dilakukan studi mengenai teknologi informasi, ROF dan laser semikonduktor. Kemudian dirancang secara optimal laser yang sesuai aplikasi ROF yaitu laser Surface Emitting Distributed Feedback (SEDFB). Pemodelan dimulai dari pemilihan material yang sesuai dengan aplikasi yang diinginkan, penentuan indeks bias dan ketebalan dari setiap lapisan penyusunnya, sampai optimalisasi parameter-parameter kerjanya, seperti confinement factor ( ??), far field, dan arus ambang. Dibutuhkan optimalisasi tebal lapisan di daerah aktif dan lapisan separated confinement heterostructure (SCH) pada laser yang menyeluruh agar tidak menurunkan kinerja parameter lain. Dari hasil simulasi didapat struktur ridge SEDFB menghasilkan operasi single mode 1550 nm dengan optical confinement factor 0,186, sudut keluaran cahaya (far field divergence) 450, optical loss 0,003 cm-1, interval grating duty cycle antara 0,5-0,.6 dan loss permukaan 24 cm-1 dan efisiensi struktur yang menghasilkan single lobe sebesar 41,78%.

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Present consumers need reliable and cost effective communication system that can support anytime, anywhere, and anymedia they want. Communication system will be effective with wireless using radio over fiber (ROF) technology. Link ROF system is most common RF transmission uses single mode optic fiber. That purpose, it needs semiconductor laser device which low noise dan low distortion at high frequencies. This Research study information technology, ROF and semiconductor laser. Then, optimum laser design due to ROF application in surface emitting distributed feedback (SEDFB) laser.

Start modeling from material selection due to application it want, determined refractive index and determined thin composition layer, also work parameter optimum is confinement factor ( ??), far field, dan threshold current. This structure need optimum layer thin in active region and separated confinement heterostructure (SCH) layer for other work parameter do not breakdown. The simulation yielded ridge SEDFB structure which optical confinement factor 0,186, far field divergence 450, optical loss 0,003 cm-1, grating duty cycle interval0,5-0,.6, surface loss 24 cm-1 dan output efisiency laser of single lobe 41,78%."

"Kopling antara amplifier permukaan miring dan fiber taper lens-ended diselidiki secara teori. Penelitian teori didasarkan pada model gelombang bidang tiga dimensi yang dihitung melalui pergeseran fasa akibat permukaan iring. Kopling diselidiki berkenaan dengan parameter-parameter berkas dari pandu gelombang amplifier lens-ended, dan juga berkenaan dengan posisi fiber. Terjadinya rugi-rugi kopling karena permukaan miring dan karena variasi dari uji lens yang terbaik, rugi untuk permukaan miring 10° ditemukan lebih kecil dari 0.5 dB dibandingkan amplifier permukaan normal.

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The coupling between angled-facet amplifiers and tapered lens-ended fibers is investigated theoretically. The theoretical investigation is based on a three-dimensional plane wave model which accounts for the phase differences introduced by the angled facets. The coupling is investigated with respect to the beam parameters of the amplifier wave guids and the tapered lens-ended fiber, and also with respect to the fiber position. For optimized lens radii the excess loss for 0l0° facet angle is found to be less than 0.5 dB compared to a normal facet amplifier."

"ABSTRACTThe frequency dobled Rd: YAG laser (532 nm/10ns, 15mj/pulse) uses a pulsed, frequency dobled; which provides a monochromatic, energy source with extremely high peak power and to has capability to develop of latent fingerprint on various surface. In the porous surfaces, this laser to has superiority, the compared with the development another methods, like powder and chemical method in latent fingerprint development. The high peak power of the laser causes Palmar sweat: contain a variety compounds, among them amino acids, oils, enzymes, vitamins and other chemicals with in the print to fluoresce. Some latent fingerprints will fluoresce in their natural state during exposure to this laser energy. The natural state fluorescing prints make can be documented and recording by high-resolution TV cameras and monitor for maximum sensitivity. The next step, the compare latent fingerprints products with visible impression by comparable instruments, see patterns of the friction ridges and be found same amount of their galton detail. "

"ABSTRACTLaser induced thin film production (LITFP) technique was employed for making plumbum (Pb) thin film by nitrogen laser deposition in miniature scale. The energy of nitrogen laser operated at 12.5 kv, 90 torr was 3.5 mj with 5 ns pulse duration, thus producing peak power at around 0.7 MW. Pb plasma of 1 cm diameter was generated in each laser bombardment, producing thin film above the glass substrate. The thin film characteristics were measured by means of their thickness and surface morphology using scanning electron microscope (SEM). It was proved that there was a linear relationship between the number of laser shots and film thickness."

"With the growth of optical communications using Low toss optical. fibers. the need for an optical switching system that exchanges optical. signals without any optoelectric and electro optic converter may arise. In this study, an experimental model of sliding prism switch using planar micro lens array has been constructed. The performance of the constructed switching device was studied by measuring insertion Loss. coupling efficiency and cross talk. The experiment shows that the measured results of insertion losses that is 6 and 7 dB are greater than the theoretically calculation that is 1.3 dB. The modulated signal has been measured as we t t ; the shape of the signal does not change after passing through the switch and on the other hand the amplitude of the output signal. is tower than the input signal due to the transmission Loss. I t is concluded that the experimental model of sliding prism demonstrate the potential application of planar micro lens in optical switch device."

"ABSTRACT

Probing of the atmospheric parameters have been done by many scientists since a century ago up to present with various techniques. A simple system of laser radar without using any collimated beam but a reflected mirror as transmitter and a small cassegranian type (10.5 an in diameter) telescope as receiving was constructed to investigate the relative Mie backscattering coefficient by utilizing a nitrogen laser as a light source in the range of measurement bellow 1 Km. The backscattered light received by the receiving telescope is converted into electric current by photomultiplier and is shown and known as "A scope" display on an oscilloscope. SNR of the signal from photomultiplier was increased by using a boxcar integrator and its output could be recorded with XY recorder."