Abstract: An optical reflection band filter structure for selectively blocking radiation within a preselected range of wavelengths is described which comprises a plurality of multipole elements of preselected configuration deposited with prescribed spacing in a periodic array on a substrate of dielectric material, each multipole configuration comprising a central element of metal and having shape corresponding to the overall shape of the multipole and a plurality of spaced metal segments, each space between adjacent segments being filled with a segment of material characterized by a transition from superconducting phase to insulating phase upon being heated to a characteristic transition temperature, each transition segment disposed outwardly from the center of the multipole element having lesser thickness than, or different composition from, the next inwardly disposed transition segment, the innermost transition segments having thickness substantially equal to that of the metal segments and central element.

Abstract: An optical modulation method and apparatus uses superconductive oxide material for the optical modulation element. The current, magnetic field, temperature or pressure applied to the superconductive oxide material is varied so as to induce a superconduction-normalconduction transition, and the resulting variation in optical characteristics such as the reflectivity, transmissivity or refractive index of the superconductive oxide material modulate the input light. The method and apparatus are fast in operation and simple in structure. The method and apparatus also detect the variation in the current, magnetic field, temperature or pressure as a change in the reflectivity, transmissivity or refractive index of the superconductive oxide material on the basis of a superconduction-normalconduction transition.

Abstract: A thin film dc SQUID and its driving electronic circuitry configured with very high symmetry. The SQUID loop is formed with four holes at the respective ends of crossed slits. Each of these holes forms a single turn secondary for symmetrically arranged pairs of modulation coils and signal coils. The geometrical placement of the modulation coil transformers with respect to the signal coil transformers results in a device which nominally has no mutual inductance between the two groups of coils when the SQUID is biased for normal operation. The external driving circuit is configured to preserve the highly balanced nature of the chip and forces equal magnitudes of current to flow in all four of the bias leads.