Scalar Product in the Space of Waveguide Modes of an Open Planar Waveguide A.L. Sevastianov, L.A. Sevastianov, A.A. Tiutiunnik and N.E. Nikolaev EPJ Web of Conferences, 108 (2016) 02041 Published online: 09 February 2016 DOI: 10.1051/epjconf/201610802041