6. Conclusion
We presented a general method to evaluate the fundamental capacity of fiber-optic communication systems. We considered
a 2000-km transmission line and found a fiber capacity of 5 bits/s/Hz. The method presented can be applied to different
transmission lines to assess the ultimate capacity achievable using advanced electronic and optical technologies.
Acknowledgements We acknowledge fruitful discussions with Jim Gordon, Bob Tkach, Andy Chraplyvy and Adel Saleh.
This work was supported by DARPA under contract HR0011-06-C-0098.