High Birefringence Triangular Optical Nanowire in Suspended-Core Fiber for Temperature Sensing

Triangular optical nanowires that present a high birefringence and a very strong confinement are fabricated. The nanowires are created by tapering suspended-core fiber down to core diameters below 1 μm. This process leads to nanowires with very high protection from the external medium, easy handling, and a fast connection to standard single-mode fiber, enabling remote sensing. The triangular nanowires present a high birefringence with an order of magnitude of 10-3. The advantage of the triangular nanowires is that the spectra present a sinusoidal interference pattern generated by the two main modes (fast and slow axis). These triangular nanowires can be used as sensing elements in different interferometric configurations. Finally, a Sagnac interferometer containing the triangular nanowires is characterized as a temperature sensor. Temperature sensitivity is enhanced to -56.2 pm/K in the 810 nm nanowire when compared with conventional suspended-core fiber, where the temperature sensitivity is residual.