Abstract: A multi-port optical device for transferring optical signals, or portion of optical signals, from one transmission element to another is disclosed. The inventive optical device comprises a pair of graded index lenses having an interposed Fabry Perot etalon. Moreover, the functionality of the device may be modified by varying the transmission characteristics of the etalon, which may be effected by varying the optical path length of the etalon. In operation, the optical device utilizes the graded index lenses as image transfer lenses between transmission elements wherein wavelength selectivity therebetween is afforded by the filtering mechanism associated with the etalon. The optical device may be used as a wavelength multiplexer or as an optical splitter. Moreover, by utilizing a piezoelectric transducer, the optical device may be converted to operate as an optical switch.

Abstract: Disclosed is a dense channel packing wavelength division multiplexed optical fiber communication system that is parsimonious in its cable length requirements and that does not require the presence of widely tunable lasers at the remote terminals. The system comprises a central station and N remote stations (N frequently greater than about 50) connected to the central station by optical fiber means that comprise a "backbone" and l (1<l<N) fiber "laterals". Associated with each remote station RS.sub.i is a predetermined wavelength .lambda..sub.i, typically in the spectral region 1.25-1.6 .mu.m. The central station comprises means adapted for generating electromagnetic radiation of a multiplicity of distinct wavelengths including all .lambda..sub.i. The radiation from the central station is coupled into the backbone fiber and transmitted to the laterals and the remote stations. Each remote station RS.sub.i comprises means for selecting the radiation of the associated wavelength .lambda..sub.

Abstract: Compressive strain in cabled optical fibers can cause buckling of the fibers and resulting microbending loss. To measure the longitudinal compression in cabled optical fibers, a modulated laser beam is directed through a first fiber and looped back to the origin by a second fiber. Next, the cable is stretched until tensile strain is indicated by a change in phase of the modulated signal. The amount of stretching required indicates the degree of compression on the fibers in the unstretched cable, and hence the amount of excess length of fiber in the cable. To measure excess fiber in relatively long lengths of cable, a portion of the cable can remain reeled, and the strain applied to the unreeled portion. A correction factor can be determined for slippage between the fiber and sheath in the reeled portion.

Abstract: A method is disclosed for determining the index of refraction profile of a stepped or graded index type optical fiber having a core encased within a surrounding cladding. An interferogram is formed with a beam of radiant energy passed transversely through the optical fiber. Fringe line shift is measured at a series of points corresponding to a series of mutually parallel ray chord paths extending through the core at mutually diverse minimum radial distances from the core axis. That portion of the measured fringe line shift attributable to discrete differences in indices of refraction of cylindrical core ring portions of thicknesses defined by successive minimum radial distances in the series of ray paths and that of the cladding is sequentially calculated from the outermost core ring portion inwardly towards the core center.

Abstract: Microbending loss is reduced and abrasion protection is afforded for optical fibers by relatively thick polymer coatings characterized in part by a preferred elastic tensile modulus and cold flow property. The coating process uses rapid cooling of a liquid application to promote rapid gelation or solidification and thus achieve uniform coating diameter without beading. Fibers so coated are formed into ribbon structures having definite center-to-center fiber spacing. Preparation of coated fibers or ribbon structures for splicing is achieved by solvent stripping of the coating.

Abstract: For improved thrust responsiveness and smooth transition of the various zones of an augmentor of an augmented jet engine powered aircraft, the time to prefill the fuel manifolds of the zones are calculated from preselected parameters so as to be on line upon light-off. The throttle lever signal is rate limited so that the preascertained manifold volume of each zone divided by the zone filling fuel flow produces a signal indicative of the time to open the normal fuel fill valve to prefill the manifold at the proper time and in the right sequence using a rate limited throttle lever signal.