Hi Mateusz,

Related with your main question, I suppose the standars are being prepared nowadays (literature claims those reasons), but until date, i dont know if ITU/IEEE standars are available. I attach you some studies on your aim.

IMcDonough, 2007: justification os such efforts.

Bosco, 2011: DWDM performance simulations

Narang, 2012: performance analysis of Super DWDM with OADM and modulation formats

Aloisio, 2012: actual DWDM designs applied.

Hope it helps, 

Cheers

- McDonough, J. (2007). Moving standards to 100 GbE and beyond. Communications Magazine, IEEE, 45(11), 6-9.

- Bosco, G., Curri, V., Carena, A., Poggiolini, P., & Forghieri, F. (2011). On the performance of Nyquist-WDM terabit superchannels based on PM-BPSK, PM-QPSK, PM-8QAM or PM-16QAM subcarriers. Journal of Lightwave Technology, 29(1), 53-61.

- Narang, V. (2012). Performance Analysis of Super DWDM with OADM and Modulation Formats (Doctoral dissertation, THAPAR UNIVERSITY); Narang thesis in http://dspace.thapar.edu:8080/dspace/bitstream/10266/2156/1/

- Aloisio, A., Ameli, F., D'Amico, A., Giordano, R., Giovanetti, G., & Izzo, V. (2012). Performance Analysis of a DWDM Optical Transmission System. Nuclear Science, IEEE Transactions on, 59(2), 251-255.

Just ITU as answed before ... G.872. OTN , IEEE do not ...