D-Microfibers

A simple mechanical setup was used to polish a standard single mode optical fiber in order to make it asymmetric. The polished fiber was tapered down maintaining the D-shape transversal profile. Its broken symmetry along with the extended evanescent field, due to the dimensions of the microfiber, implies a potentially high birefringent waveguide as well as a high-sensitivity external refractive index device. An experimental maximum sensitivity of S ≈ (3.0±0.2)×10
⁴
nm/RIU was achieved, other experimental and numerical results supporting our initial assumptions are also presented.