Abstract: An electromagnetic device, including: a microfiber or other optical waveguide configured to guide an electromagnetic field output by an electromagnetic field source, the microfiber or other optical waveguide having a diameter that is less than or on an order of a wavelength of the electromagnetic field output by the electromagnetic field source; and a first optical material in contact with the microfiber or other optical waveguide, wherein at least a contact region of the microfiber or other optical waveguide and the first optical material is immersed in a liquid or cured dielectric that has an index of refraction less than the index of refraction of the microfiber or other optical waveguide.