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The characteristics of the typical nonlinear states in an optically injected laser system with single- and dual-beam injection are analyzed and compared numerically. Both single- and dual-beam optical injection systems can generate periodic oscillations and chaos states but with different characteristics. By observing the evolution process of periodic oscillations, it is found that dual-beam injection induced periodic oscillations have multiple time series patterns including continuous periodic signals with single peak (CPS) and continuous periodic signals with subharmonic (CPSSH), while for single-beam injection with either of the dual-beam injection parameters generated periodic oscillations, the extremum numbers of the time series equal to the frequency period numbers of the optical spectrum. In addition, the great advantages of bandwidth enhancement effect for chaos oscillations are obtained by using dual-beam injection. Furthermore, extensive numerical simulations reveal that dual-beam injection system undergoes period-doubling routes to chaos, which is identical to that in single-beam injection system. Finally, the characteristics of newly clustered NDFWM dynamics in dual-beam injection system are analyzed.

We propose a downlink broadcast transmission scheme of radio-over-fiber (RoF) system based on period-one (P1) dynamic of dual-beam optically injected semiconductor laser with tunable microwave subcarrier frequency. The transmission performance of 2.5 Gb/s data in a 60 GHz RoF system is demonstrated through numerical simulations. It is found that the proposed transmission scheme can easily generate a single-sideband (SSB) optical modulation by adjusting the injection strength level of two master lasers (ML), which is favorable to reduce the fading effect due to chromatic dispersion. Furthermore, influences of the pulse amplitudes and duty cycles of the downlink data on the transmission properties are investigated. It is observed that the oscillation of the relative power at the base station induced by fiber dispersion does not vary apparently with the modulation parameters. Once the SSB spectrum is generated by dual-beam optical injection, the downlink transmission performance of the proposed RoF system keeps good stability and reliability.

In this work, optical wavelet de-noising with several different types of wavelets such as db4, coif4 and dmey wavelet was applied at the end of the 40 Gbit/s multi-span intensity-modulated fiber communication systems. The results of numerical simulations carried out in different fiber links demonstrated that the optical wavelet de-noising method could remove the random amplitude fluctuation induced by the interaction of EDFA’s ASE noise and optical fiber’s dispersion and nonlinearity. The SNR and BER curves of the optical bit sequence without and with optical wavelet de-noising in dispersion compensation fiber link were plotted to show the effectiveness of the wavelet de-noising in the fiber-optic communication systems and wavelet de-noising with demy wavelet can achieve better result than with other type wavelet.