Abstract:
A method of creating a codoped layer (18) includes creating a first layer (14) having a first dopant and at least one other layer (16) have another dopant, then interdiffusing the dopant to create a substantially homogeneous codoped layer. More than one dopant may be deposited in a single layer. The creating conditions may be optimized for each layer (14, 16). Further, when the creation of a layer includes sequential deposition and consolidation, conditions for each process may be optimized within the layer creation. While at least two layers (14, 16) are formed, the interdiffusion substantially eliminates any stratification or layer structure.
Abstract:
The present invention discloses a method of fabricating rare earth-doped preforms for optical fibers. A silica soot is deposited as a layer with high porosity on an inner surface of a silica-based tube by a modified chemical vapor deposition (MCVD) process at a temperature high enough to produce the silica soot but low enough to avoid sintering of the soot into the silica-based tube. The silica-based tube is then immersed in a solution including a rare earth element and optionally a codopant element for impregnation. The excess solution is drained and the silica-based tube is dried in a stream of chlorine and inert gas at an elevated temperature. Then, the rare earth element and the optional codopant element are oxidized under an oxygen partial pressure at a temperature high enough to overcome kinetic limitations against oxidation. Finally, the soot layer is consolidated while flowing oxygen and optionally a mixture of chlorides of a second codopant element at a sintering temperature at which the second codopant element reacts with oxygen to form codopant oxide which is delivered around the rare earth element oxide deposited in the soot layer. In the method of the current invention, one or more rare earth elements are codoped with preferred codopants including but not limited to Ge, Al, P and/or B to enhance the performance of the rare earth ions. Other dopants may also be used in conjunction with the preferred dopants for modifying the refractive index of the core.
Abstract:
Gemäß der Erfindung kann der Verlauf der Fluoreszenzbande von Lichtwellenleitern, die mit Erbium und Aluminium dotiert sind, weiter abgeflacht werden, wenn der Kern als zusätzliches Dotiermittel Fluor enthält, z.B. in Form von ErF₃ und AlF₃. Anwendung: Verstärker aus optischer Faser mit abgeflachtem Verstärkungsprofil.
Abstract:
An optical amplifier for amplifying an optical signal having a signal wavelength λ s , comprises an optical fibre (20) having an erbium doped core (34) surrounded by cladding (42, 32, 30), a pump (22) for pumping the fibre with pump light at a pump wavelength λ p coupled to the fibre, said erbium doped optical fibre having a NA higher than 0.2, the difference in the coefficient of thermal expansion of the core adjacent the core/cladding interface and the coefficient of thermal expansion of the cladding at at least one radius less than 2µm from said interface being lower than a predetermined value, corresponding to a ratio of erbium loss to background loss, at said pump wavelength, greater than a minimum ratio calculated by a given increasing function of the ratio erbium loss/background loss versus erbium loss, in which said minimum ratio is about 20 when erbium loss is 0.15 dB/m and about 120 when erbium loss is 3.5 dB/m.
Abstract:
On détermine en continu la teneur en diborane (B 2 H 6 ) dans un mélange avec du silane (SiH 4 ) par mesure en continu de la masse volumique au moyen d'un densimètre à tube vibrant (14) et détermination subséquente de la teneur en B 2 H 6 . Application à l'élaboration de couches de verre à base de bore, phosphate et silicate ("Boro-phosphosilicate glass").
Abstract:
Disclosed is a method of making a polarization retaining single-mode optical fiber. Longitudinal grooves are formed on opposite sides of a cylindrically-shaped core preform having a glass core (11') surrounded by cladding glass (12'). The core preform is inserted into a glass tube, the tube is shrunk onto the core preform, and the interface between the core preform and the tube (27) is fused to form a solid preform having longitudinal apertures (14') on opposite sides of the core. An etchant gas is flowed through the apertures to enlarge the apertures into holes having a substantially round cross-section. Inserted into each aperture is a stress rod formed of glass having a coefficient of expansion different from that of the cladding glass. The resultant draw blank is drawn to form a single-mode optical fiber having a core that is subjected to a stress-induced birefringence.