Abstract: A multimode optical fiber includes a central core and an outer cladding (e.g., an outer optical cladding). Typically, the optical fiber's central core is a depressed, central core having an alpha-index profile (i.e., a graded-index profile), an outer radius r1, and a maximum refractive index difference ?n1 with respect to the outer cladding. The central core's alpha-index profile has a minimum refractive index at the central core's outer radius r1 that corresponds to a refractive index difference ?nend with respect to the outer cladding. Exemplary optical-fiber embodiments may include an inner cladding having an outer radius r2 and a width w2. Exemplary optical-fiber embodiments may include a buried trench having a width w3 and an outer radius r3. Furthermore, exemplary optical-fiber embodiments may include an intermediate cladding having an outer radius r4 and a width w4.

Abstract: A multimode optical fiber includes a central core and an outer cladding (e.g., an outer optical cladding). Typically, the optical fiber's central core is a depressed, central core having an alpha-index profile (i.e., a graded-index profile), an outer radius r1, and a maximum refractive index difference ?n1 with respect to the outer cladding. The central core's alpha-index profile has a minimum refractive index at the central core's outer radius r1 that corresponds to a refractive index difference ?nend with respect to the outer cladding. Exemplary optical-fiber embodiments may include an inner cladding having an outer radius r2 and a width w2. Exemplary optical-fiber embodiments may include a buried trench having a width w3 and an outer radius r3. Furthermore, exemplary optical-fiber embodiments may include an intermediate cladding having an outer radius r4 and a width w4.

Abstract: A single mode optical transmission fiber comprises a depressed core having at least 0.41 weight percent fluorine and an index difference (|?n1|) with pure silica greater than 1.5×10?3, a depressed cladding having at least 1.2 weight percent fluorine and an index difference (|?n2|) with pure silica greater than 4.5×10?3 and an index difference (|?n2|?|?n1|) with the depressed core greater than or equal to 3×10?3.

Abstract: A single mode optical transmission fiber comprises a depressed core having at least 0.41 weight percent fluorine and an index difference (|?n1|) with pure silica greater than 1.5×10?3, a depressed cladding having at least 1.2 weight percent fluorine and an index difference (|?n2|) with pure silica greater than 4.5×10?3 and an index difference (|?n2|?|?n1|) with the depressed core greater than or equal to 3×10?3.

Abstract: A single mode optical transmission fiber comprises a depressed core having at least 0.41 weight percent fluorine and an index difference (|?n1|) with pure silica greater than 1.5×10?3, a depressed cladding having at least 1.2 weight percent fluorine and an index difference (|?n2|) with pure silica greater than 4.5×10?3 and an index difference (|?n2|?|?n1|) with the depressed core greater than or equal to 3×10?3.

Abstract: A single mode optical transmission fiber comprises a depressed core having at least 0.41 weight percent fluorine and an index difference (|?n1|) with pure silica greater than 1.5×10?3, a depressed cladding having at least 1.2 weight percent fluorine and an index difference (|?n2|) with pure silica greater than 4.5×10?3 and an index difference (|?n2|?|?n1|) with the depressed core greater than or equal to 3×10?3.

Abstract: The invention relates to a method for the use of a local area fibre optic network for enabling data communication. The method comprises the steps of supplying an intensity-modulated light signal to at least one fibre of the fibre optic network by means of a transmission unit and receiving the intensity-modulated light signal by means of the receiver unit that is connected to the fibre. The intensity of the intensity-modulated light signal is modulated for the purpose of providing a bit rate of at least 30 Gbps for the data communication. The light for providing the intensity-modulated light signal has a wavelength that ranges between 1200 nm and 1400 nm. The invention further relates to a method for altering a 10 Gigabit ethernet local area fibre optic network for the purpose of adapting the fibre optic network for data communication at a bit rate in excess of 30 Gbps. The invention also relates to a fibre optic network.

Abstract: A coupling element for an optical transmission system, in which the coupling element comprises a convex lens having a refractive index which is dependent on the radius r of a shell in the lens, and a holder. Use is preferably made of lenses having a refractive index N.sub.(r) =N.sub.1 .multidot.(2-(R/Ro).sup.2)1/2, where N.sub.1 is the refractive index of the core of an optical fiber (approximately 1.55) and Ro is the radius of the lens.The coupling of monomode fibers via lenses of this kind can be effected wth large dimensional tolerances.

Abstract: The invention relates to a method of and a device for providing an outer surface of an envelope which is concentric to a light-conductive core, around a monomode optical fiber. According to the invention, the eccentricity of the fiber and the envelope may be for example, 0.1 .mu.m for a core diameter of 3 .mu.m. This accuracy is acieved by splitting a light beam, emerging from the end of a fiber which is clamped in an envelope, into two subbeams by means of rotating optical means, each of the beams producing a circular image. By a suitable choice and adjustment of the optical means, the two light beams will form oppositely moving images when the fiber end is displaced with respect to the axis of rotation and observation. When the images are concentric, the fiber end is situated on the axis of rotation. Machining of the envelope by the use of a tool which rotates around the axis of rotation results in an envelope which is concentric to the light-conductive core of the fiber.

Abstract: A device for coupling a light source, in particular a semiconductor laser, to an optical fiber in which the light source and the optical fiber are each connected to a cylindrical or part-cylindrical support and a coupling member is provided having two V-shaped grooves enclosing mutually a substantially right angle, in which the cylindrical supports, possibly carried by an additional member, after their mutual adjustment in the V-shaped grooves, are secured to the contact member. One of the supports may advantageously be provided in a V-shaped groove of a cylindrical or part-cylindrical auxiliary member which is secured in one of the V-shaped grooves of the coupling member.