Design approaches to carry out broadband absorption in laterally assembled hexagonal silicon nanowire (NW) solar cells are investigated. Two different methods are proposed to improve the current density of silicon NW solar cells. It is observed that the key to the broadband absorption is disorder and irregularity. The first approach to reach the broadband absorption is using multiple NWs with different geometries. Nevertheless, the maximum enhancement is obtained by introducing irregular NWs. They can support more cavity modes, while scattering by NWs leads to broadening of the absorption spectra. An array of optimized irregular NWs also has preferable features compared to other broadband structures. Using irregular NW arrays, it is possible to improve the absorption enhancement of solar cells without introducing more absorbing material.
In this paper, we investigated the coherent noise in communication systems and use a method for reducing the noise mixed with the signal. We use a general model of N-signal and N-noise frequency mixing. The numerical results are shown in this paper. A proper choice of the parameters can reduce the noise at the output of the data recovery system.
In this paper, we present influence of optical mixing of microwave signals on conversion of the noise power spectral density (NPSD), using a directly modulated semiconductor laser and an interferometer to convert frequency modulation into intensity modulation. The results show the influence of the modulation index and modulation frequency in an optical link by considering optical mixing.
In this paper, a novel measurement of FM-noise is shown. We present both experimental and simulation results by considering the external RF phase modulation, with good agreement. The results show for the first time, the influence of the phase modulation index, modulation frequency, in the conversion of FM-noise to intensity noise in an optical link by considering all effects on RF modulated light emitted by a 1550 nm DFB laser.
In this paper, we propose and demonstrate a new and original model for theoretical calculation of the noise power spectral density (NPSD) in phase-modulated optical links. The phase modulation is operated in the RF frequency range by an external phase modulator. The NPSD is derived for the first time in interferometric systems, by considering all effects such as the <i>1/f</i> FM noise of the laser, and white noise applied to light from a 1550 nm DFB laser, with phase modulation. The results show for the first time the influence of the phase modulation index, modulation frequency, and interferometric delay in the phase-to-intensity noise conversion. Theoretical calculations and experimental results of conversion of FM-noise to intensity noise in an optical link are shown with good agreement.