Abstract: A method for preparing optical fibers for an evanescent field coupler by forming a groove along a top surface of a substrate block, wherein the groove is formed shallower than the diameter of a stripped fiber. An optical fiber is positioned in the groove, wherein a center portion of the optical fiber is stripped of its coating. The optical fiber is glued in the groove, then polished to remove a portion of its cladding to form a coupling region, while not polishing the top surface of the substrate block. An optical signal is applied to an end of the optical fiber while loss of the optical signal is measured at the coupling region. Polishing and monitoring are repeated until a desired loss value is reached. The coupler can be added to an operating optical communication system.

Abstract: An evanescent field coupler comprising a coupler holder, a first optical fiber mounted in a first substrate block, and a second optical fiber mounted in a second substrate block. The first substrate block is compliantly mounted to the holder. Means are included for positioning the substrate blocks with respect to the other for switching and adjustment of the coupling ratio. The compliant mount elastically deforms during switching and/or alignment to facilitate accurate, repeatable switching, while maintaining the desired coupling ratio between the optical fibers.

Abstract: Signal energy in an installed optical fiber is extracted without using a physical connector, by an improved process in which the fiber is bent to within a prescribed range of angles, then controllably heated, and thereafter controllably cooled. The resulting structure exhibits relatively low permanent stress. A fiber end conventionally placed at the bend point receives unusually useful amounts of optical signal which can be routed to optical branch circuits in, for example, a building or a LAN.

Abstract: This invention provides an apparatus and a method of filtering a MM Wavelength Division Multiplexed (WDM) signal operating in the 1548 to 1560 nm region. The wavelengths of the MM are spaced 1-12 nm apart and centered about 1558 nm. The adjustable filters for tuning MM optical signals encompass a carousel and a mechanical system for positioning one of the filters in the path of the MM WDM signal and tracking the signal. An algorithm controls the mechanical system for tracking and positioning one of the filters in the path of the MM WDM signal. The filter in position filters one of a plurality of wavelengths and tunes the filter to compensate for temperature changes.

Abstract: Particles comprising a core surrounded by at least one shell wherein at least one of the core or one of the shells is a metal and at least one of the core or one of the shells is a dielectric material which exhibits a third order nonlinear response. The "shell" of a metal particle may be the adjacent region of a medium in which said particle is suspended, said medium having a third order nonlinear response. In a preferred embodiment, the particles are suspended in a dielectric medium that may be linear or may exhibit a third order nonlinear response. Enhancement of the effective .chi..sup.(3) of the particles and suspensions result from the concentration of the electric field in and around the particles at the plasmon resonance frequency of the metal.