Abstract: A ferrite layer formation process that may be performed at a lower temperature than conventional ferrite formation processes. The formation process may produce highly anisotropic structures. A ferrite layer is deposited on a substrate while the substrate is exposed to a magnetic field. An intermediate layer may be positioned between the substrate and the ferrite to promote bonding of the ferrite to the substrate. The process may be performed at temperatures less than 300° C. Ferrite film anisotropy may be achieved by embodiments of the invention in the range of about 1000 dyn-cm/cm3 to about 2×106 dyn-cm/cm3.

Abstract: A ferrite layer formation process that may be performed at a lower temperature than conventional ferrite formation processes. The formation process may produce highly anisotropic structures. A ferrite layer is deposited on a substrate while the substrate is exposed to a magnetic field. An intermediate layer may be positioned between the substrate and the ferrite to promote bonding of the ferrite to the substrate. The process may be performed at temperatures less than 300° C. Ferrite film anisotropy may be achieved by embodiments of the invention in the range of about 1000 dyn-cm/cm3 to about 2×106 dyn-cm/cm3.

Abstract: A silica sol-gel fabrication process is provided which allows improved control of the shrinkage that takes place during the drying of a gel body. In particular, the invention makes it possible to attain extremely low shrinkage through the completion of the drying stage, e.g., below 1% linear shrinkage, in relatively large sol-gel bodies of (dry weight) 1 kg or more, typically 10 kg or more, or even 40 kg or more, compared to the much higher shrinkages typically encountered. Specifically, use of a particular polymeric additive makes it possible for a gel body to experience linear shrinkage at least 55% less than an identical process without the polymeric additive.

Abstract: A silica sol-gel fabrication process is provided which allows improved control of the shrinkage that takes place during the drying of a gel body. In particular, the invention makes it possible to attain extremely low shrinkage through the completion of the drying stage, e.g., below 1% linear shrinkage, in relatively large sol-gel bodies of (dry weight) 1 kg or more, typically 10 kg or more, or even 40 kg or more, compared to the much higher shrinkages typically encountered. Specifically, use of a particular polymeric additive makes it possible for a gel body to experience linear shrinkage at least 55% less than an identical process without the polymeric additive.

Abstract: Ceramic monoliths are described which exhibit tunable coefficients of thermal expansion from about −5 to −11×10−6° C.−1 near ambient temperatures. These two-phase ceramics, which are fabricated, for example, by reactive sintering of WO3 and ZrO2, consists of a matrix of ZrW2O8 with inclusions of ZrO2 having diameters less than 10 &mgr;m. Additives may increase the density of the monoliths to greater than 98% of the calculated density. Green body densities, pre-sintered particle size distribution, sintering atmosphere, microstructure, and mechanical properties are discussed. These ceramics may be used as substrates for thermally compensating fiber Bragg gratings.

Abstract: Ceramic monoliths are described which exhibit tunable coefficients of thermal expansion from about −5 to −11×10−6° C.−1 near ambient temperatures. These two-phase ceramics, which are fabricated, for example, by reactive sintering of WO3 and ZrO2, consists of a matrix of ZrW2O8 with inclusions of ZrO2 having diameters less than 10 &mgr;m. Additives may increase the density of the monoliths to greater than 98% of the calculated density. Green body densities, pre-sintered particle size distribution, sintering atmosphere, microstructure, and mechanical properties are discussed. These ceramics may be used as substrates for thermally compensating fiber Bragg gratings.

Abstract: Ceramic monoliths are described which exhibit tunable coefficients of thermal expansion from about −5 to −11×10−6° C.−1 near ambient temperatures. These two-phase ceramics, which are fabricated, for example, by reactive sintering of WO3 and ZrO2, consists of a matrix of ZrW2O8 with inclusions of ZrO2 having diameters less than 10 &mgr;m. Additives may increase the density of the monoliths to greater than 98% of the calculated density. Green body densities, pre-sintered particle size distribution, sintering atmosphere, microstructure, and mechanical properties are discussed. These ceramics may be used as substrates for thermally compensating fiber Bragg gratings.

Abstract: The invention provides an improved process for fabricating devices containing metallized magnetic ceramic material, such as inductors, transformers, and magnetic substrates. In particular, the unique vias utilized in the process of the invention allow fabrication of devices from multiple unfired ferrite layers with only a single via-coating step, thereby avoiding the need numerous punching steps. Moreover, there is no need for expanding the dimensions of the vias and thus no need for internal metallization. The invention therefore provides for green tape-type fabrication of devices such as inductors, transformers, and magnetic substrates in a manner faster, less complex, and more reliable than current methods. The invention also relates to use of an improved conductive material in such a process, the conductive material containing silver/palladium particles, ferrite particles, a cellulose-based or other organic binder, and a solvent.

Abstract: The invention is a sol-gel extrusion process which allows fabrication of both thick and thin wall tubes. For example, the process is capable of preparing silica overcladding tubes in a manner easier than sol-gel casting processes, and also capable of preparing relatively thin substrate tubes, which are difficult to cast. According to the invention, a silica dispersion containing a stabilizing agent is provided, a gelling agent is added to the dispersion to induce gellation, and the resultant gel is extruded into a silica body, in the substantial absence of polymeric material from the gel. Substantially avoiding the inclusion of such polymeric material in overcladding and substrate tubes offers significant commercial advantages by reducing the time and energy required to remove organic materials from the tube bodies, by reducing environmental impact, and by reducing the amount of impurities introduced in the tubes.

Abstract: The invention provides an improved process for fabricating devices containing metallized magnetic ceramic material, such as inductors, transformers, and magnetic substrates. In particular, the unique vias utilized in the process of the invention allow fabrication of devices from multiple unfired ferrite layers with only a single via-coating step, thereby avoiding the need numerous punching steps. Moreover, there is no need for expanding the dimensions of the vias and thus no need for internal metallization. The invention therefore provides for green tape-type fabrication of devices such as inductors, transformers, and magnetic substrates in a manner faster, less complex, and more reliable than current methods. The invention also relates to use of an improved conductive material in such a process, the conductive material containing silver/palladium particles, ferrite particles, a cellulose-based or other organic binder, and a solvent.

Abstract: A tunable fiber grating comprises a temperature-sensitive body secured to a fiber having a fiber grating region for transmitting thermally-induced strain to the grating. The amount of strain and hence the degree of wavelength tuning are controlled by adjusting the temperature of the temperature-sensitive body, wherein the extent of adjustment is preferably pre-determined according to feedback from a wavelength detector. Large thermal strains obtainable with the present invention allow a wide range of wavelength tuning with a relatively small and convenient temperature change near ambient temperature. In a preferred embodiment, the temperature-sensitive body is cylindrical and comprised of a nickel-titanium alloy bonded to the grating. In alternative arrangements, the thermal strain effect can be amplified. An add/drop multiplexer employing the tunable gratings is also described.

Abstract: The method of making a metallized magnetic substrate for devices including a magnetic component involves providing an unfired ceramic body. In one exemplary embodiment, the method further involves making one or more vias through the ceramic body, coating the via side walls with conductive material, forming an aperture through the ceramic body, such that an aperture edge intersects the via, and metallizing the unfired ceramic body such that a conductive pathway is formed that includes the conductive material in the via. Finally, the metallized unfired ceramic body is fired in conventional fashion, optionally followed by deposition of additional conductor material.

Abstract: Conventional optical gratings are relatively temperature sensitive. This sensitivity is generally undesirable but can be reduced or eliminated by attaching the grating to a support member having a negative coefficient of thermal expansion. Exemplarily the member comprises Zr-tungstate and/or Hf-tungstate. The thermal expansion can be tailored by admixture of positive expansion coefficient material (e.g., Al.sub.2 O.sub.3, SiO.sub.2) to the negative expansion coefficient material (e.g., ZrW.sub.2 O.sub.8), or by a variety of other techniques.