Abstract: Tip shrouds or other shrouds with multi-slope geometries are generally implemented using segments, since performing the necessary cut for an alternative split-ring design is difficult given conventional cutting processes. However, a segmented design generally results in more leakage, relative to a split-ring design. Accordingly, a split-ring multi-slope design is disclosed that can be more easily manufactured. In particular, a continuous ring may be cut along a linear path to produce a split ring, and then the ends of the split ring may be machined to form complementary shiplap portions. The split ring may then be compressed for installation by overlapping the shiplap portions, to form a seal against leakage through the shroud.

Abstract: Tip shrouds or other shrouds with multi-slope geometries are generally implemented using segments, since performing the necessary cut for an alternative split-ring design is difficult given conventional cutting processes. However, a segmented design generally results in more leakage, relative to a split-ring design. Accordingly, a split-ring multi-slope design is disclosed that can be more easily manufactured. In particular, a continuous ring may be cut along a linear path to produce a split ring, and then the ends of the split ring may be machined to form complementary shiplap portions. The split ring may then be compressed for installation by overlapping the shiplap portions, to form a seal against leakage through the shroud.

Abstract: The present invention provides devices and methods for Raman amplification and dispersion compensation. According to one embodiment of the present invention, a dispersion compensating device includes a dispersion compensating fiber having a dispersion more negative than about ?50 ps/nm/km over a wavelength range of about 1555 nm to about 1615 nm; a Raman gain fiber having a dispersion more positive than about ?40 ps/nm/km over a wavelength range of about 1555 nm to about 1615 nm; and a pump source operatively coupled to the dispersion compensating fiber and the Raman gain fiber, the pump source operating at a pump wavelength, wherein the dispersion compensating fiber has a Raman Figure of Merit at the pump wavelength, and wherein the Raman gain fiber has a Raman Figure of Merit at least about equivalent to the Raman Figure of Merit of the dispersion compensating fiber, and wherein the dispersion compensating fiber and the Raman gain fiber are arranged in series between the input and the output of the device.

Abstract: An isotopically-altered, silica based optical fiber is provided having lower losses, broader bandwidth, and broader Raman gain spectrum characteristics than conventional silica-based fiber. A heavier, less naturally abundant isotope of silicon or oxygen is substituted for a lighter, more naturally abundant isotope to shift the infrared absorption to a slightly longer wavelength. In one embodiment, oxygen-18 is substituted for the much more naturally abundant oxygen-16 at least in the core region of the fiber. The resulting isotopically-altered fiber has a minimum loss of 0.044 dB/km less than conventional fiber, and a bandwidth that is 17 percent broader for a loss range between 0.044-0.034 dB/km. The fiber may be easily manufactured with conventional fiber manufacturing equipment by way of a plasma chemical vapor deposition technique. When a 50 percent substitution of oxygen-18 for oxygen-16 is made in the core region of the fiber, the Raman gain spectrum is substantially broadened.