Abstract: Improved single-mode optical waveguide fibers comprising a central core region, surrounded by an inner cladding region through which light at a chosen signal wavelength will propagate to an appreciable degree along with propagation of same in the central core region, the inner core region further surrounded by an outer cladding region, the improvement comprising germanium dioxide in the inner cladding region at a concentration within the range of about 0.005 percent by weight to about 1 percent by weight of said inner cladding region, effective to significantly reduce the concentration of oxygen atoms in the inner cladding region which are available to form defects that cause hydrogen-induced attenuation. Also provided are core preforms, overclad preforms, and processes for making the fibers, core preforms and overclad preforms.

Abstract: A method of making 1.times.2 or 2.times.2 overclad couplers, switches and the like such that the process is more reproducible and loss characteristics are improved. Such couplers are typically made by inserting the stripped portions of two active optical fibers into a tube, heating the tube midregion to collapse it onto the fibers and stretching the central portion of the collapsed midregion to achieve the desired coupling characteristics. The improvement involves the insertion of one or two spacer fibers into the tube bore along with the active fibers to take up empty space that had been present in tube bore and to prevent an active fiber from sagging and crossing over the other fiber when the tube is heated during the tube collapse step.

Abstract: A package for a high power semiconductor laser comprising a hermetically sealed container filled with a dry gaseous medium containing oxygen. The presence of oxygen in the laser atmosphere is counter to standard practice in the art which teaches the use of an atmosphere of a dry inert gas.

Abstract: A liquid cooling method and apparatus for rapid cooling of a hot glass fiber. In FIG. 1, an open ended liquid coolant container (12) is provided at its lower end with an inverted funnel surface (34). A vertically running, hot glass fiber (42) of indefinite length is continuously drawn through the container, as the container continuously receives a coolant liquid at its upper open end (30). The liquid continuously drains from the container lower open end (32) by flowing along flow surface (36) of the inverted funnel (34), downwardly and away from the glass fiber (42). The temperature of the fiber relative to the temperature of the coolant liquid is such that a vapor barrier surrounding the hot fiber is formed due to boiling of the liquid in a zone surrounding the fiber. This vapor zone facilitates diversion of the liquid (change in direction of flow) from the vertical to an angle thereto, along the inverted funnel surface.

Abstract: A method of making a thick walled glass tube by depositing glass particles on the surface of a glass tube, sintering the particles, and drawing the resultant structure to form a capillary tube having a predetermined desired inside diameter.

Abstract: An optical fiber coupler is formed by providing a glass tube having a longitudinal aperture. Two contiguous carbon tubes are disposed within the longitudinal aperture which is thereafter collapsed thereon. A glass capillary tube is formed by removing the carbon tubes. The tube can be stretched, overcoated with additional glass, and again stretched to form a precision capillary tube which is severed into coupler-length tubes. Two optical fibers, which are shorter in length than the aperture of a coupler-length tube, are centered in that aperture. The midregion of the resultant assembly is heated and collapsed about central portions of the fibers. The central region of the resultant coupler preform is heated and drawn to reduce the diameter thereof. The end regions of the aperture, which are not diminished in size by the aforementioned processing, function as receptacles into which optical fibers can be inserted to make connection to the coupler.

Abstract: An improved method for crystallizing amorphous or polycrystalline material is disclosed, which method employs a novel intermediate product. A film of material to be crystallized is formed on a substrate. A porous silica cap is formed over the film. The resultant intermediate product is heated to melt the film which crystallizes upon cooling. Gases generated during melting of the film escape through the porous cap which also functions to prevent deleterious agglomeration of the material while it is in a molten state.