| 摘要 |
The present invention relates to an in-line optical amplifier that can be coupled to optical fiber, wherein the amplifying medium has a substantially larger mode field than the optical fiber to which it is coupled. The present invention has realized a design to utilize a very high power pump launching a multimoded signal having approximately 1 W of pump power into a block of erbium doped glass having a mode field diameter orders of magnitude larger than the mode field diameter of erbium doped fiber. This invention provides a relatively inexpensive optical amplifier that is compatible for use in an optical fiber telecommunications system or for other uses. Advantageously, this invention provides a device that does not require unwieldy lengths of erbium doped fiber to form an amplifier. By using a block of glass having a rare earth therein, packaging, temperature stabilizing and temperature tuning of the amplifier also become practicable. Furthermore, a cylindrical block of glass having planar ends, lends itself to applying coatings or filters thereto, thereby forming selective filters at ends of the erbium doped block to allow the pump light in, and the signal light in at opposite ends, while preventing light at the pump wavelength to propagate out with the amplified signal.
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