Abstract: An arrangement for converting diverging polarized laser emission from a semiconductor laser into a convergent beam includes two optical lenses and an optical isolator formed of a Faraday rotator and at least one polarizer arranged in the beam path of the laser emission. The lens which lies farther from the semiconductor layer is a component of the Faraday rotator and is formed by a plano-convex lens having an curved side facing the semiconductor laser.

Abstract: A lens system for focussing a divergent laser beam, particularly for converting the three dimensional amplitude and phase distribution of the highly divergent laser beam of a semiconductor laser into the amplitude and phase distribution of the fundamental mode coupleable into a monomode fiber is disclosed. The lens system comprises a front element in the form of a collecting aplanatic meniscus and one or more following refractive lenses for focussing the laser beam emerging from the front element. The refractive front face of the meniscus facing the object side aberration free point is designed such that it at least approximately has the form of a phase surface of the divergent laser beam emanating from a location at least close to the object side aberation free point which impinges the meniscus. The front face thereby becomes largely aberration free.

Abstract: A method for visualizing the core of a monomode fiber by means of a microscope lens is disclosed, said monomode fiber comprising a jacket of undoped silica glass and its core of silica glass being doped with Geo.sub.2 or TiO.sub.2. An invisible microscope image of the core is generated in an image plane B with the microscope lens with ultraviolet light from the wavelength range between 230 nm and 380 nm and the invisible image is converted into a visible image by means of a video system, whereby the clear contrast contained in the invisible microscope image which is based upon the employment of the ultraviolet light is preserved in the visible image.

Abstract: The breaking strength of glass fibers, such as generally utilized in optical communication techniques, is materially improved by subjecting a glass fiber to a heat treatment whereby the glass fiber is relatively slowly pulled through a controlled heat zone having a temperature gradient extending from a temperature at or at least relatively close to the softening temperature of the glass fiber to about room temperature.

Abstract: A device for converting the frequency of coherent light from a prescribed wavelength range characterized by utilizing at least one crystal consisting of a nonlinear optical material. In order to obtain phase adjustment or phase matching, the device of the present invention provides a crystal possessing a property, which, at least for a specific wavelength of .lambda..sub.u from a wavelength range, the phase adjustment angle .theta..sub.0 and the phase adjustment temperature of T.sub.0 do not depend upon the wavelength at least in the first approximation. Thus, known methods of phase adjustments such as continuously rotating the crystal and/or changing the temperature are not required to adjust the phase when the frequency of the wavelength is changed within certain limits.

Abstract: A method for the production of single-material optical fibers having a light conducting core supported within a protective sleeve by at least one extremely thin support component characterized by providing a blank having a core and at least one support component disposed within a protective sleeve, heating the blank to a drawing temperature, drawing the blank into a form of an optical fiber and either during the drawing or subsequent thereto, transversely stretching the support component to reduce the ratios of the thickness of the support component to its transverse width and to the thickness of the core of the fiber. In one embodiment of the invention, subsequent to the drawing, a fluid such as a gas under excessive pressure is applied internally to the protective sleeve to expand and inflate the sleeve to transversely stretch the support component.