In this work, simple solar cells using cuprous oxide were fabricated and characterized. The solar cells in this experiment
used cuprous oxide plate as detecting electrode and copper wires which were woven into a net-shape with a gap size of 2
x 2 cm as a counter electrode. Twenty samples of solar cells were fabricated with oxide layer which were thermally
grown in temperature up to 550 <sup>o</sup>C. Samples with variations in oxidation time (15 minutes, 30 minutes, 40 minutes, and
45 minutes) and distance between electrodes (2 cm, 3 cm, and 4 cm) with an electrolyte solution of <i>NaCl</i> with molarity
of 2.188 mol/l were produced. The samples were characterized by measuring their <i>V-I</i> curve. For this purpose, a simple,
own-made solar simulator were fabricated and characterized. Using curve fitting technique, parameters such as FF (Fill
Factor), efficiency, open circuit voltage, short circuit current, internal resistance, and performance degradation as a
function of time of the cells were extracted. The result shows optimum efficiency of 4.573. 10-<sup>4</sup>%, while optimum
oxidation time is 40 minutes and optimum distance between electrodes is 3 cm.
A characterization method of planar waveguides, namely m- line measurement has been utilized to reconstruct refractive index profile in planar waveguide. This method gives some values of incident angle that can be coupled in to waveguide, which after some mathematical calculations can provide its mode indices. To reconstruct the refractive index profile from mode indices as a function of normalized film thickness we use Inverse Wentzel-Kramers-Brillouin method. Furthermore, we select the value of n<SUB>0</SUB> that give the smoothest refractive index profile by finding the minimum sum of the squares of second differences of the profile. For this purpose, we implement reiterative, trial and error method on some values above the measured fundamental effective index value as a guess of the surface index. The result has been smoothed using curve fitting algorithm to exponential and Gaussian profile. The result confirm that index profile of planar waveguide can be reconstructed mathematically and the profile can be obtained more accurate by the proposed curve fitting technique than the basic IWKB method.
A method of index measurement, the so-called rn-line technique has been applied to measure the refractive index of planar waveguides fabricated by ion exchange method in BK7 substrate. By placing a prism coupler on the surface of the planar waveguide, the coupling angle of modes guided in the waveguide was measured. The prism has apex angle of 44.9° and is made of ZnSe with refractive index 2.59073 . The values of the coupling angles were then processed mathematically to obtain the effective indices of the guided modes. The number of modes guided in the waveguide depends on the duration of ion exchange process, and the effective refractive indices have been determined for the respective modes. The result for zero order mode, ranging from 1.5183 to 1.6887 for TM modes and from 1.5182 to 1.6891 for TE modes. On the other hand,for the duration of ion exchange process of 48 hours, five modes were guided in the waveguide and the effective refractive indices were 1.6887; 1.6167; 1.5818; 1.5649 and 1.5465 for zeroth, the first, the second, the third and the fourth modes, respectively. The use of the rn-line technique has been proved to be simple and effective with high accuracy in the characterization purpose of waveguides.
Refractive index profile of surface channel waveguides can be determined by analyzing the near-field intensity pattern. A mathematical model, the inverse Helmholtz equation, is derived in order to use these data to reconstruct the refractive index profile under consideration. In this work, the measured near-field intensities are preprocessed by means of gamma correction, background noise subtraction, Fast Fourier Transform, and low pass finite impulse response (FIR) digital filter. Several types of FIR windows are chosen. The results are used to reconstruct the refractive index profile of the waveguide. The results show that the application of low pass FIR digital filter by using Hamming window reduces noises better than other windows. The application of this method in determination of refractive index profile of annealed proton exchange LiNbO<SUB>3</SUB> channel waveguides is demonstrated.
Conference Committee Involvement (1)
Third International Seminar on Photonics, Optics, and Its Applications (ISPhOA 2018)