Abstract: Electromagnetic resonators according to the invention comprise a first body, exemplarily a split thin ring, that is disposed between two planar field confining plates. The thickness (t) of the first body is less (typically less than 1/2 or 1/10) of the outer radius (R) of the body, and the distance between the first body and the confining plates is less than R. In preferred embodiments the first body comprises superconducting material. Resonators according to the invention can be readily assembled into relatively compact filters that are easily tunable, can have large quality factor, and offer the possibility of single mode operation. Such filters can advantageously be used in, e.g., wireless communications systems.

Abstract: It has been discovered that glass of composition xM.sub.2 O.(1-x)SiO.sub.2 can have lower intrinsic loss than pure SiO.sub.2, for 0<x.ltorsim.0.03 and M=Na, K, and/or Rb. Furthermore, it has been discovered that co-doping with F can increase the range of reduced intrinsic loss to x.about.0.07, for M=K and/or Rb. Disclosed is optical fiber that comprises the novel low intrinsic loss glass,, typically in the core.

Abstract: An optical fiber system which includes a source of electromagnetic radiation, e.g., a laser, in optical communication with a multicomponent halide glass optical fiber is disclosed. This system is distinguished from previous such systems in that, within the context of the inventive system, the multicomponent halide glass fiber exhibits lower intrinsic loss than when used in previous such systems. This is achieved by choosing the source in relation to the composition of the fiber so that the wavelength of at least a portion of the electromagnetic radiation emitted by the source is substantially equal to the minimum intrinsic loss wavelength for the fiber, as determined using a new, more accurate procedure.

Abstract: Raman-active optical fiber having very large Raman cross section is disclosed. The fiber comprises glass that has two major components, a glass-forming first component (GeO.sub.2, SiO.sub.2, AsO.sub.1.5, or combinations thereof) and a heavy metal oxide second component (PbO, BiO.sub.1.5, SbO.sub.1.5, TlO.sub.0.5, or combinations thereof), with the first and second major components making up at least 70 mol %, preferably at least 90 mol %, of the glass. The maximum relative Raman cross section .sigma..sub.r of the inventive glass is at least 15, preferably greater than 20, where .sigma..sub.r =.sigma..sub.RA /.theta..sub.SiO.sbsb.2, and where .sigma..sub.RA and .sigma..sub.SiO.sbsb.2 are the maximum 0.degree. K. Raman cross sections of the inventive glass and of pure vitreous SiO.sub.2, respectively.

Abstract: Amorphous niobates and tantalates of the alkali metals lithium, potassium, and sodium which may be off-stoichiometric with regard to the related octahedrally coordinated crystalline compositions manifest high values of dielectric constant and ionic conductivity. Electrode bearing devices may be utilized, inter alia, as capacitors, electrolytic cells, and bolometers.