The generation of satellite communications with flexible and efficient transmission of radio signals requires a large number of low interfering beams and a maximum exploitation of the available frequency spectrum.
In this paper we propose and demonstrate by simulation an all-optical modulation format conversion from non-return-tozero on-off keying (NRZ-OOK) at 10 Gb/s to dual-polarization quadrature-phase-shift keying(DP-QPSK) at 20 Gb/s for each channel, by cross phase modulation (XPM) in a polarization-maintaining highly nonlinear fiber (PM-HNLF). The obtained results show a constellation diagram with an error vector magnitude (EVM), 17.26% and 18.79%, for each channel. The input powers of the two NRZ-OOK channels were 16.9dBm and 13.9dBm for a 3km fiber length. We also studied the impact of the nonlinear fiber length in the conversion of the signal and analyzed the system performance based on error vector magnitude (EVM) for different fiber lengths.
Advanced modulation formats are an emerging area since they allow reducing the symbol rate while encoding more bits per symbol. This allows higher spectral efficiencies. In addition, we can achieve higher data rates using lower-speed equipment like in all-optical format conversion systems, an important step for the development of systems with high transmission rates. In this paper we study the impact of some impairments found in all-optical advanced format conversions based on cross phase modulation (XPM) on a highly nonlinear fiber (HNLF), such as amplified spontaneous emission (ASE), nonlinear fiber length and group velocity dispersion (GVD), and analyze its performance based on error vector magnitude (EVM) for different bitrate transmissions. This simulation study is applied on earlier proposed phase modulated format conversion where n nonreturn-to-zero on-off keying (NRZ-OOK) channels at 10 Gb/s are converted into a return-to-zero m phase shift keying (RZ-mPSK) at 20Gb/s. We extend the work with simulations and show the results for n NRZ-OOK channels at 20Gb/s, 40 Gb/s and 50Gb/s to RZ-PSK at 40Gb/s, 80 Gb/s and 100Gb/s, respectively.