Method and apparatus for fabricating a preform for an active optical fiber, active optical fiber and amplifier

• Main Authors: SANDOZ, FREDERIC, RIBAUX, PHILIPPE, OTHENIN, PETER, HAMEL, PHILIPPE, PEDRIDO, CARLOS
• Format: Patent
• Language: English; French; German
• Published: 09.07.2008
• Subjects: CHEMISTRY; GLASS; MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES; METALLURGY; MINERAL OR SLAG WOOL; OPTICAL ELEMENTS, SYSTEMS, OR APPARATUS; OPTICS; PHYSICS

The present invention relates to a method and an apparatus for fabricating a primary, secondary or higher order preform (1, 10, 100) that can be used for drawing an active optical fiber (8). The present invention further relates to an active optical fiber (8), designed for amplification or attenuation purposes, drawn from said preform (1, 10, 100) and to an optical amplifier (600, 601) using a laser active optical fiber. With the inventive method, preforms (1, 10, 100) can be produced with primary and silica tubes (11; 11d; 111), which limit an interior or outer space that can be filled with primary or secondary silica grain (51, 510). In order to achieve activity, particularly laser activity of the fiber (8) subsequently drawn from the preform (1, 10, 100), at least one of the silica tubes and/or the primary or secondary silica grain (51, 510) are doped with A/A-material (520) of at least one sort. After the assembly the preform (10, 100) of secondary or ternary order, which already contains at least one preferably inventive processed or unprocessed primary preform, then the secondary or ternary preform (10, 100) is heated in order to obtain a final preform from which the active optical fiber (8) can be drawn simultaneously or in an a subsequent process step. An inventive active optical fiber (8) can be used in an attenuator or in an optical amplifier (600, 601), which comprises a source unit (62) from which a pump signal can be delivered to the active zone of the inventive optical fiber (8).