The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 28, 2005
Filed:
Dec. 23, 2002
Katsuhiko Hakomori, Sapporo, JP;
Hiroyuki Furukawa, Sapporo, JP;
Kazuhito Ogawa, Sapporo, JP;
Fujitsu Limited, Kawasaki, JP;
Abstract
An optical amplifier amplifies a light signal inputted to an optical amplifier fiber and outputs an amplified light signal, by exciting the fiber with an excitation light. The optical amplifier can keep its output light level constant and stable and reduce the excitation light when the light inputted to the fiber is cut off, just by detecting the optical output level at a post-stage of the fiber. The optical amplifier comprises a first control circuit, a second control circuit and a selector circuit. The first control circuit amplifies the difference between a first predetermined voltage and an o/e-converted voltage of the optical amplifier fiber output light to output an amplified voltage. The second control circuit amplifies the difference between the o/e-converted voltage of the excitation light and a selected one of the first control circuit output voltage and a second predetermined voltage to output an amplified voltage and controls the excitation light based on the second control circuit output voltage. The selector circuit detects a change in the first control circuit output voltage and depending on the change, selects the first control circuit output voltage or a second predetermined voltage.