Single mode propagation is an important requirement for optical waveguide devices for use with single-mode fiber, it
can reduce the coupling loss. In this paper, a technique is used for calculating the field distribution of the polymeric
Y-junction rib waveguide. The technique is based on the combination of the effective index method(EIM) and the
variational method(VM). It is mixed between the advantages of each method and avoided their disadvantages, where EIM
can make the calculations procedures simple but it has some difficult to find the field distribution, other wise, VM can be
used with very good accuracy to find the field distribution. An algorithm is implemented to study the effect of the
structure parameters on the field distribution of the polymeric Y-junction rib waveguide. In our simulation, the core layer
is PU-FTC (firstname.lastname@example.orgμm),the cladding layers were NOA73 (email@example.comμm) and Epoxylite9653 (firstname.lastname@example.orgμm).
The obtained single mode rid waveguide structure parameters are: the core thickness is 1.5μm, the rib height is 0.2μm,
the rib width is 5μm.