We present the theoretical study of an all-solid highly birefringent fiber with an anisotropic core fully compatible with SMF-28 fiber and without use of external stress zones or air holes. We propose a fiber with a core composed of interleaved subwavelength layers of silica and germanium-oxide-doped silica. The optimized nanostructured fiber has a phase birefringence of 1.42×10−4, and an effective mode area and numerical aperture similar to SMF-28 fiber. We predict coupling losses of 0.1 dB for bidirectional coupling with the SMF-28 fibers.