Applications of Optical Solitons It is well known for the past 50-60 years that intense laser beams can form into soliton/solitary waves. Those exist either spatially in CW beams or temporally in ultra-short pulses, and their existence and stability have been analyzed in a variety of situations. 
My question is about their applications - do they have any? I know that in the 90's temporal solitons were considered as candidates for fiber-optics communication systems, but that for many reasons this line of research have never passed to commercial system. 
Is there an example of spatial or temporal solitons that have been applied in commercial systems?
Thanks
 A: 
My question is about their applications - do they have any?

Yes, optical solitons have loads of potential applications.  One of the best things about solitons is that one can construct them to propagate without dispersion – a frequency and/or wavenumber dependence in the phase velocity of a signal.  First, I will present a little background/perspective for why dispersion in transmission is important then I will provide some examples.
Dispersion
Dispersion is a big problem in transmission lines because the signals are generated with a finite bandwidth, i.e., there are multiple frequencies used to carry the signal.  If each signal frequency propagates at a different rate in an optical fiber, then the arrival time of a single pulse/wavepacket of information will depend upon the frequency/wavelength of the initial signal.
In high datarate lines, they often measure the amount of dispersion in units of picoseconds squared per kilometer or ps2/km, called a dispersion parameter.  Let's define $\beta$ as the dispersion parameter.  Then we can estimate the amount of dispersion, $\Delta$, using $\beta$ and the transmission distance, $L$, given by:
$$
\Delta \simeq \sqrt{ \frac{1}{2} \ \beta^{2} \ L } \tag{1}
$$
where $\Delta$ will have units of time.
To put this in perspective, assume we have a 1 Gbit/s bit rate (e.g., a 1 ns pulse separation with an equivalent symbol rate) and our signal pulses are 100 ps in duration, i.e., their peaks are separated by 10 pulse widths.  Suppose we use a wire with $\beta$ ~ 15 ps2/km and wanted to transmit information over 10,000 km (i.e., rough distance from US to Japan).  Then we find $\Delta$ ~ 1060 ps.  Meaning, the receiving group will see pulses over 10 times longer in duration than the ones that were initially transmitted.  Thus, the received pulses overlap making separation of two pulses more and more difficult.  This can result in signal degradation or complete loss, depending on the amount of spreading and other factors.  The use of data encoding and other error detection schemes are employed to test/verify the quality of the received signal.
Examples

Is there an example of spatial or temporal solitons that have been applied in commercial systems?

Yes, fiber optic solitons have been employed in commercial use since 2002 [e.g., see Mitschke et al., 2012 and references therein], specifically for long-distance, high speed transmission lines.

I know that in the 90's temporal solitons were considered as candidates for fiber-optics communication systems, but that for many reasons this line of research have never passed to commercial system.

A quick Google search of the phrase applications of optical solitons gave me over 200,000 results, a few of which on the first page discussed the commercial applications and some even talk about the history of their commercial use.
If you search the phrase commercial applications of optical solitons, you can find a PDF copy of the Mitschke et al. [2012] paper on the 2nd page of results.  If you look through their bibliography, there are numerous references that clearly discuss the application of this phenomena in commercial use.
So I am not sure why you argue they have not been used in commercial systems.
References


*

*Hasegawa, A. "An historical review of application of optical solitons for high speed communications," Chaos 10(3), pp. 475–485, 2000.

*Mitschke, F., et al., "Recent Insights about Solitons in Optical Fibers," Nonlinear Phenomena Complex Systems 15(4), pp. 369–377, 2012.

