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:
May. 05, 2014
Filed:
Oct. 15, 2003
Hideaki Sugiya, Kawasaki, JP;
Yoshihito Onoda, Kawasaki, JP;
Hideaki Sugiya, Kawasaki, JP;
Yoshihito Onoda, Kawasaki, JP;
Fujitsu Limited, Kawasaki, JP;
Abstract
Two rare earth-doped optical fibers are connected in series and used to amplify input light. A splitter is installed between these two rare earth-doped optical fibers. The input light is monitored by having the portion of the input light that is branched off, by the splitter received by a photodiode. Excitation light output from a laser light source is guided by optical couplers and supplied to the above rare earth-doped optical fibers. A control circuit controls the output light level and, at the same time, stops the output from the laser light source when the input light level drops below a specified threshold value. The gain of the first stage rare earth-doped optical fiber while excitation light is being supplied is larger than the loss that occurs due to branching of the input light by the splitter.