Permanently bent single mode optical fiber as novel evanescent wave sensor

A novel optical fiber sensing scheme based on evanescent wave interaction is proposed. It involves locally and permanently bent single mode optical fibers. Permanent bends induce significant power coupling between core and cladding modes. Order and number of excited cladding modes depend on bend features and determine the field profile at the output of the bent region. This in turn constitutes a simple mechanism to tailor the field distribution in single mode optical fibers useful for spatial light modulation. Moreover, since guided cladding modes are strongly influenced by the surrounding refractive index, the power transmitted at the output of the bent region as well as its dependence on the optical wavelength are strongly sensitive to the SRI opening new scenarios in sensing applications.