The nanocrystalline structure of Lithium niobate (LiNbO3) was prepared and deposited onto substrate made of quartz by utilize pulse laser deposition technique. The effect of substrate temperature on the structural, optical and morphological properties of lithium niobate photonic film grown was studied. The chemical mixture was prepared by mixing the raw material (Li2CO3, Nb2O5) with Ethanol liquid without any further purification, at time of stirrer 3hrs but without heating, then annealing process the formed material at 1000C° for 4hrs. We characterized and analyzed the LiNbO3 nanostructure thin films by utilize Ultra-Violet Visible (UV-vis). The UV-vis measurements show that, when the substrate temperature increases, the values of transmission, absorption and energy band gap will decreased, but the values of reflection and refractive index will increased. That means the LiNbO3 thin film prepared at substrate temperatures 300C° give the best result for manufacture the optical waveguide.
Picosecond pulse measurements at 1.5 p m have a key role in OTDM system characterization. In particular, several techniques are currently being used with their respective measurement limitations. Indirect characterization techniques such as autocorrelators, cross correlators have the property of symetrizing the pulse and are required to know its description for correct deconvolution. Streak cameras are mainly limited by timing jitter at high-repetition-rate signals. Other techniques"' have been demonstrated but still now the deviation between the measured and the original pulse may be significant when the pulse is asymetric. Here, we present an optical time spectrum analyzer dedicated for characterization of high-repetition-rate (>5 GHz) short optical pulses at 1.5 Fm with low or high optical power. The basic idea is based on a "time lens,"3 which processes the incoming signal so that the optical spectrum and the wavelength scale are directly proportional to the input pulse and the time scale respectively. In addition we have designed and realized an analyzer4 allowing measurement of high-repetition-rate signal (>5 GHz) with low input optical power of 1 mW. Figure 1 shows the bloc diagram of the analyzer we have built. The incoming optical time slots containing the optical pulses are gated to reduce the duty cycle of optical slot pulses, which are then dispersed before being processed by the phase m o d~l a t o r .~ The signal issued from the output of the modulator can then be analyzed by an optical spectrum measurement. If the dispersive media is adjusted adequately with the Input Pulse Lk t I @ I Command Geneiator st function 2nd function Time lens Optical path ThA3 Fig. 1. Optical time spectrum analyzer for short-pulse measurement. Time(ps) 0 T U 3laser with a sensitivity of 135 ps/nm corresponding to 50 ps/div on this figure. Fig. 2. Time spectrum analyzer measuring a pulse from a gain-switched phase-modulation index then the spectrum measured and wavelength scale are proportional to the optical pulse and the time scale respectively as shown in relations (1) and (2).where A stands for the maximum phase-modulation index and 0 , for the frequency modulating the phase modulator, Ao operating wavelength, and c the speed velocity of light. We measured an optical pulse issued from a gain-switched laser with a repetition rate of 5 GHz on the optical time spectrum analyzer. An optical power of only 1 mW is required to perform the measurement. The resolution of the analyzer depends mostly on the design of the phase modulator. In this measurement, we futed it close to 10 ps. We have compared the deconvolved output detected from a fast photodiode and oscilloscope with direct optical time spectrum analyzer results. The deconvolved results gives a pulse measurement of -24 ps FWHM whereas with the optical time spectrum analyzer we measured 19 ps (Fig. 2 ) . From this graph displaying the optical spectrum, the wavelength scale has been translated in time scale using relation (2) and fixed to 50 ps per div.Concerning the de...
We propose and analyse a silicon based hybrid modulator on the nano thin film of the lithium niobate or commonly known as silicon-on-insulator technology. The Mach–Zehnder stripe optical waveguide of electro-optical modulator operats at GHz frequencies with large bandwidth and low losses between electrical and optical frequencies.The design and simulation of Mach-Zehnder modulator is based on a hybrid integration platform of silicon and lithium niobate that satisfies a single mode condition. The Silicon stripe waveguide is of 0.6 μm thickness in a silicon on insulator (SOI) of width 15 um and 0.05 um thickness x-cut LiNbO3 thin film, all sets use the pulse laser deposition (PLD) method. The Optical electric field distributions and effective mode area in the optical-waveguides were studied and discussed in this designated waveguide.The relationship between the width of waveguides regions with effective mode index and effective mode area was investigated. At 0.6 um width of waveguide and 0.2 um thickness, the effective mode index 1.9802 was recorded while the effective mode area 0.144 um2 was monitored. This shows the decrement in both: the width and thickness of the waveguide with the effective mode index and effective mode area.
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