Modelagem de efeitos da dispersão cromática na transmissão de rádio sobre fibra utilizando fotônica de microondas

Abstract

This work presents a proposal for closed analytical models for the analysis of radioover- fiber (RoF) communication systems using microwave photonics. The influences of the optical fiber chromatic dispersion effects and the electro-optical modulators and photodetector nonlinearities on the received signal power were investigated. This contribution on the subject makes it possible to analyze the transmission of radiofrequency (RF) and microwave signals over long distances. By setting some parameters, it is possible to evaluate different applications such as generation and conversion of high frequency signals and photonic filters in the RF and microwave bands. Analytical solutions applicable to modern communication systems that employ 5G and 6G resources and that use analogue optical links were developed. For this, the Graf addition theorem was used for the Bessel functions of first kind and the Fourier transform, showing the spectra for the different parts of the system in the frequency domain. The results between the proposed large signal models and the approximate models were compared, highlighting the most significant differences. The models contemplate parameters of interest in the projects of these systems, including signals with large amplitudes. Among the most relevant values highlighted are the modulation RF signals frequencies, the modulation indices, the losses, the nonlinearities and the transmission coefficients of the electro-optical modulators. Also, the wavelength and power of the laser, the photodetector responsivity and nonlinearity, the attenuation, the length and the chromatic dispersion of the optical fiber, are evaluated. To evaluate the proposed analytical models, the radio over fiber links with phase and intensity modulations, both with direct detection, were investigated. The analog optical modulation formats such as phase, double sideband intensity, single sideband and suppressed carrier, were adopted. External electro-optical modulators such as phase and Mach-Zehnder intensity with dual-drive and with single drive, were used. In addition, applications are presented in microwave frequency generation and in OOK digital information transmission, both using the proposed models. With a single model, it is possible to determine the link responses with different analog optical modulations that use phase or amplitude modulators and with direct detection.