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Abstrak :
ABSTRACT Recently, the Indonesian researchers have anticipated the research on photonic devices especially on semiconductor laser. According to the anticipation above, the scope of this research is on photonic devices particularly on design and performance fabrication of 1.55 um GaInAsPfInP semiconductor laser using intrinsic single-mode layers. The semiconductor laser was designed using intrinsic single-mode layers that consist of 4 (four) layers i.e., 2 (two) waveguiding layers with 1,15 p.m, AMB (Anti Melt Back) layer with 1.3 pm, and active layer with 1.55 pm. The layers were growth by designing 0.17 pm waveguiding layer thickness, 0.1 pm active layer- and AMB layer thickness, respectively. The performance optimizing were on optical confinement factor of the single-mode layers and threshold current. The design and simulation results that threshold current of 702,5 mA and the optical confinement factor of 0.801 can be achieved. In addition, the optimum performance was obtained with thicker AMB layer, thicker active layer, and thinner wave-guiding layers.

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ABSTRAK Para peneliti di Indonesia hingga saat ini telah mengantisipasi penelitian di bidang devais fotonik terutama diode laser semikonduktor. Penelitian pada tesis ini di bidang devais fotonik diutamakan pada rancang bangun dan simulasi unjuk kerja dari diode laser semikonduktor pada panjang gelombang 1,55 um dengan bahan GalnAs-PIInP menggunakan lapisan mode tunggal intrinsik. Pada rancang bangun dirancang suatu diode laser semikonduktor dengan lapisan mode tunggal yang terdiri dari empat buah lapisan GaInAsP masing-masing 2 buah lapisan pandu gelombang dengan panjang gelombang 1,15 µm, lapisan aktif dengan 1,55 gm, dan lapisan anti cair ulang (ACU) dengan 1.3 µm. Untuk penumbuhan dipilih lapisan pandu gelombang setebal 0,17 gm, lapisan aktif setebal 0,1 gm dan lapisan ACU setebal 0,1 gm. Dalam perancangan, parameter faktor perangkap cahaya dari lapisan mode tunggal dan besamya arus ambang memegang peranan penting untuk mengoptimalkan unjuk kerja. Hasil rancang bangun dan simulasi memperlihatkan bahwa unjuk kerja perhitungan dengan arus ambang sebesar 702,5 mA dan faktor perangkap cahaya lapisan mode tunggal sebesar 0,801 dapat dicapai. Selain itu optimalisasi unjuk kerja dapat diperoleh dengan cara mempertebal lapisan ACU, membuat lapisan aktif tidak tipis dan lapisan pandu gelombang tidak tebal.

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An N2 laser system that consists of transversely excited atmospheric (TEA) oscillator and transversely excited (TE) amplifier has been designed and constructed. The laser system employs single common spark gap for both oscillator and amplifier. The optimum operating voltage is 15 kV at 2 Hz repetition rate. The measured energy of the output oscillator-amplifier system has maximum value of 55 pJ and beam divergence of 2 mrad horizontally and 1 mrad vertically.

Synchronization between the oscillator and amplifier was achieved by varying the gas pressure in amplifier tube, inductance between oscillator and spark gap as well as the optical path between the oscillator and amplifier. The result of its characterization showed that this system is capable to producing BOO % amplification in a single pass.

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ABSTRACT
The molecular weight of Polymer material can be determined using optical system by measuring the intensity of scattered light at low angle light scattering and its the incident beam, based on Rayleigh scattering have developed by Debye has known as Static Light Scattering.

To carry out this measurement, an optical system was constructed using a HeNe laser light with a certain intensity, and the light passed through a polymer solution and its scattered light were then detected using a photo multiplier.

To obtain the experimental results, the set-up was tested using a polymer standard, which has been already known its average molecular weight. In this experiment were used the polymer standard with average molecular weight 35000, 110000 and 200000. Furthermore, this optical experiment set-up constant, were used for determining the average molecular weight of the polymer samples.

In this experiment a linear curve relation between the optical Rayleigh polymer and the polymer concentrations was constructed, and by extrapolating this linear curve up to zero concentration the molecular weight of polymer can be determined.

From the laboratory test we got that the experimental set up could be used for the measurement of polymer, which has the molecular weight larger than 35000 to 200000, with tolerance 4 percent.

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A compact, simple and low-cost transversely excited atmospheric (TEA) pressure ultraviolet nitrogen laser {337 nm) has been designed and constructed employing the conventional Blumlein circuit. The measured energy of the output pulse of 337 nm is around 80 -J at 25 kV of charging voltage and l atm operating gas pressure. The beam divergence is found to be 7.7 mrad horizontally and 1.5 mrad vertically. The energy output decreases slightly with increasing gas pressure and gas flow rate, while the beam divergence is relatively stable with respect to the same operating parameters.

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For 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.

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An experiment demonstrating the principle of mode recognition has been performed. In the experiment, a He-Ne laser with phase synchronized TEMo1 mode is used. This laser has two stable (bistable) states corresponding to be emission of a right- and left- hand helical waves. Injection of light of one state can switch the laser emission to this state. A hologram is used to convert an image to the state of the laser and in turn irradiation of the image into the hologram produces radiation corresponding to the state. Injection of this radiation into a second laser causes the laser switch to the respective state and remain in that state. A second hologram convert the laser states into two images and using the second hologram, the two images can be recognized, distinguished and stored.

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Observation of fluorescence decay signal of condensed-state molecular samples in the time domain has proved very useful for its identification and analysis. In order to overcome the noise problem in the generally weak fluorescence signals a double-gated boxcar integrator has been designed and incorporated into a spectrometer. The design concept and the working principle of this spectrometer is presented along with detailed description of its subsystems. Performance of this spectrometer has been tested with well-known sample (rhodamine 6G) and the results are duely analyzed. Application of this spectrometer to the measurement of fluorescence spectrum and mean life time of an E. Cali bacteria sample is also described in this work.

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The principles of frequency stabilization is to keep constant the optical path length in laser cavity by controlling the laser- tube length. In this system used temperature servo control to control the laser tube length.

As reference to an error derived by a sensitive frequency discriminator. Basically the operation of this sensitive frequency discrimantor utilized the longitudinal Zeeman Laser, which splits atomic gain profile.

When a longitudinal magnetic field is applied to an internal mirror of single mode He-Ne Laser, the active medium acquires a negative circular dichroism. There fore the intensity of the left cicular polarization (LCP) output of the, laser will be different from the intensity of the right circular polarization (RCP) output and only when the two are simmetrically disposed about the center line will their intensities be equal. This intensity difference as feedback can be detected by passing the output beam throught Wallaston prism and the two orthogonally polarized beams are received by two identical photodiodes. The difference between the output of photodiode as amplified and the resulting signal is passed throught a system controller (PID) before it is fed back as heating or cooling current of peltier elements. This current controls the resonator length thermally and lock the laser frequencies of the two polarized beam symmetrically on either side of the profile.