Slab-type optical device

Claim 1

An integrated optical device comprising: a substrate with a substantially uniform index of refraction; first monomode waveguide means, formed in said substrate, for propagating optical energy in a direction axial thereto, said first waveguide means having a dimension w 1 transverse to its axial direction; second monomode waveguide means, formed in said substrate, for propagating optical energy in a direction axial thereto, said second waveguide means having a dimension w 2 transverse to its axial direction, said first and second waveguide means intersecting one another at an angle θ1 small enough to make the variations in the distance between corresponding points of said first and second waveguide means over an incremental length in the respective axial directions of said first and second waveguide means negligible relative to said incremental length; third monomode waveguide means, formed in said substrate for propagating even mode optical energy in a direction axial thereto, said third waveguide means having a dimension w 3 transverse to its axial direction; fourth monomode waveguide means, formed in said substrate, for propagating odd mode optical energy in a direction axial thereto, said fourth waveguide means having a dimension w 4 transverse to its axial direction, said third and fourth waveguide means intersecting one another at an angle θ2; and means for coupling the intersection of said first and second waveguide means to the intersection of said third and fourth waveguide means, wherein: said dimensions w 1 and w 2 are equal, said dimension w 4 is different from said dimension w 3 , said first and fourth waveguide means are approximately axial to one another, said second and third waveguide means are approximately axial to one another, and the intersection of said first and second waveguide means is adjacent to the intersection of said third and fourth waveguide means.