Mitigation of Self-Phase Modulation in High-Peak-Power Lasercom Systems

Impact of initial pulse characteristics on the mitigation of self-phase modulation by sinusoidally time varying phase

“…In the context of the transmission of telecommunication signals, it has been shown that approximating the signal waveform with just one or two harmonics suffices to achieve a significant amount of SPM compensation (Xu et al 2002;Ulmer et al 2016;Zhu et al 2007). This can also be expected from our results in Fig.…”

“…(10) and, contrary to CTS, it evolves with the accumulated nonlinear phase shift. It is noteworthy that with the range of modulation frequencies being studied, it is possible to drive the phase modulator with the master clock that has been used in (Ulmer et al 2016) to generate RZ50-like signals. The optimum amplitude of the phase modulation is slightly higher than the value ACTS from Eq.…”

“…Indeed, while for a purely nonlinear propagation the disposition of the nonlinear element and the external phase modulator does not impact the overall SPM-mitigation process, this is no longer the case when dispersion becomes important. In practice, while post-compensation has shown to be effective when it is done in the receiver of a telecommunication system (Xu et al 2002), applications dealing with high-power pulses may favor a pre-compensation scheme to avoid damages to the optoelectronic component due to excessive optical power and mitigate the deleterious Brillouin backscattering (Ulmer et al 2016;Su et al 2013). It is noteworthy that with the phase modulation applied as a pre-compensation, the process can be reinterpreted as spectral focusing with the nonlinear phase accumulated by the pulse in propagation compensating an initial and opposite phase modulation (Zohrabian,Mouradian 1995;Oberthaler,Höpfel 1993): the spectrum is broadened by the pre-compensation, and the SPM process then compresses it back to its original shape.…”

“…This method, which emulates the use of a material with a negative nonlinear index of refraction, has proved successful in fiber-optic and free-space optical telecommunication applications using phase-shift keying systems (Xu et al 2002;Ulmer et al 2016), and in the generation of high-peak-power nanosecond pulses (Su et al 2013;Munroe et al 2009). Moreover, the technique can be integrated into existing CPA systems to deal with femtosecond pulses (van Howe et al 2006;Zhu et al 2007).…”

“…Most of the previous works are primarily experimental in nature (van Howe et al 2006;Zhu et al 2007;Xu et al 2002;Ulmer et al 2016;Su et al 2013;Munroe et al 2009) and, for instance, have not discussed the sensitivity of the technique to the initial pulse characteristics in detail. First, we recall the concept of our method and the situation being studied.…”