High resolution spectral metrology leveraging topologically enhanced optical activity in fibers

Optical rotation, a form of optical activity, is a phenomenon employed in various metrological applications and industries including chemical, food, and pharmaceutical. In naturally-occurring, as well as structured media, the integrated effect is, however, typically small. Here, we demonstrate that, by exploiting the inherent and stable spin-orbit interaction of orbital angular momentum fiber modes, giant, scalable optical activity can be obtained, and that we can use this effect to realize a new type of wavemeter by exploiting its optical rotary dispersion. The device we construct provides for an instantaneous wavelength-measurement technique with high resolving power R = 3.4 x 10(6) (i.e., resolution < 0.3pm at 1-m wavelengths) and can also detect spectral bandwidths of known lineshapes with high sensitivity. Optical rotation in a medium, which is typically small, can be enhanced by harnessing spin-orbit interaction in fiber modes. Here the authors use this effect to develop a fiber-based wavelength-measurement technique with high resolution.