A numerical study of the throughput and crosstalk in intersecting semi
conductor rib waveguides was carried out using the beam propagation me
thod, The fraction of the optical power that couples out of one input
waveguide and into the crossed waveguide falls to below two percent fo
r crossing angles greater than four degrees, A simple modification to
the waveguide shape at the X-crossing region was found to reduce the c
rosstalk for crossing angles between four and ten degrees, The crossta
lk to throughput ratio is reduced by up to a factor of nine while the
throughput is reduced by, at most, a few percent, In device structures
that combine X-crossings with curved waveguide sections this permits
greater design flexibility and improved overall loss and crosstalk per
formance.