Anisotropy of thermoelastic stresses in two-channel single-mode waveguides

The method of finite elements is used in a calculation of the field of thermoelastic stresses in two-channel single-mode fiber waveguides with identical cores located symmetrically in a shared quartz glass cladding. An analysis is made of the dependences of the stresses on the distances between the cores and of the influence of ellipticity of the cores on the magnitude and nature of the stresses with the aim of finding a structure capable of conserving the linear state of polarization in these waveguides. It is shown that the thermoelastic stresses in waveguides of this type are fundamentally inhomogeneous, but this inhomogeneity is least when the distances between the cores and from the surface of the waveguide are the same. In a structure of this type the tangential stresses are close to zero, which is a necessary condition for linear polarization of the HE₁₁ eigenmodes.