25-Gb/s optical NRZ transmission over 40 km of single-mode fiber at 1550 nm without dispersion compensation

•We propose a method for transmitting 25-Gb/s optical NRZ signals over a 40-km standard single-mode fiber at 1550 nm.•We confirm that the extinction ratio and fiber launching power can be used to control the self-phase modulation effect.•The combined effect of the GVD and SPM makes it possible to transmit 25-Gb/s optical signals over a 40-km SSMF at 1550 nm.

We present a method for transmitting 25-Gb/s optical nonreturn-to-zero signals at a wavelength of 1550 nm over a 40-km single-mode fiber without any dispersion compensation methods. We propose optimized self-phase modulation by varying parameters of the fiber launching power and the extinction ratio of optical non-return to zero signals to overcome severe signal distortions by the chromatic dispersion effect. Using the optimization of the self-phase modulation effect, we were able to transmit 25-Gb/s optical nonreturn-to-zero signals over a 40-km single-mode fiber, which can be applicable to passive optical networks with a single wavelength channel and a high split ratio. We demonstrated that the self-phase modulation effect can be controlled by the extinction ratio and the fiber launching power.