@ARTICLE {7701,
author={L.   Cancela and J. J. O.  Pires},
doi={},
journal={Journal of Optical Communications},
title={On the Behaviour of Eigenfunctions and Eigenvectors in the Performance Analysis of Optical Direct Detection DPSK Receivers with Optical Amplification},
year={2013},
month={September},
volume={34},
number={3},
pages={145-154},
ISSN={0173-4911}
}