Abstract: A composite capillary tube structure made of a plurality of glass layers and methods for making same. This composite includes inner and outer layers of fused silica glass separated by an intermediate layer of a glass material having a higher coefficient of thermal expansion than the fused silica glass. The glass material of the intermediate layer also has a glass transition temperature on the same order as that of fused silica, so that the fused silica layers are maintained under compressive forces over a temperature range of up to about 400.degree. C. Preferably, the intermediate layer is a borosilicate or aluminosilicate glass.

Abstract: An arrangement for an optical fiber pressure sensor is described. This sensor is comprised of two coating layers concentrically clad to and coaxially oriented with an optical fiber. The first coating layer is comprised of a relatively hard optically lossy material which absorbs any light radiating outwardly from the optical fiber. The second coating layer is comprised of a compliant material in which granular particles have been uniformly dispersed. In response to any pressure laterally applied to the sensor, the compliant coating layer imparts micro-bends, onto the optical fiber, which, in turn, couple light from propagating modes to non-propagating modes. As a result, the amplitude (or power) of the light exiting the optical fiber advantageously decreases in response to this pressure.

Abstract: A concentric core optical fiber comprised of an inorganic crystalline, preferably metallic, central core and an optical waveguide having an optical ring core and inner- and outer-glass cladding layers concentrically clad to the central core is described. A long length of such an optical fiber can advantageously support a heavy load for a substantial period of time without fatiguing while providing a transmission medium for optical and/or electrical signals.

Abstract: A magnetically sensitive optical fiber is described. Specifically, this fiber is comprised of a central core containing magnetostrictive material and an optical waveguide, having an optical ring core and inner- and outer-glass cladding layers, clad to the central core. The core is constructed from magnetostrictive material which is readily and inexpensively available as wire of various gauges. The wire is chosen to have a relatively large cross-sectional area with respect to that of the glass cladding layer(s). The resulting optical fiber is advantageously highly sensitive to weak magnetic fields and is also both simple and inexpensive to manufacture.

Abstract: The modified chemical vapor deposition process is practiced using an rf source as the external heat source. An rf plasma is thus established within a glass tube through which appropriate glass precursor vapors are passed. As a result of the ensuing chemical reactions, particulate material is formed within the tube and deposits on it. The hot plasma zone may be used to consolidate this particulate material into a transparent glass, and onto the interior wall of the tube. The tube is subsequently drawn into an optical fiber.

Abstract: An optical fiber is drawn from an appropriate preform using a laser whose output power is varied periodically at a rate greater than ten times a second. A fiber drawn in this manner has periodic variations in diameter which enhance the mode conversion properties of the fiber and thereby reduce the pulse dispersion of a signal transmitted through the waveguide.