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:
Apr. 25, 2000
Filed:
Aug. 28, 1998
Michikazu Shima, Kawasaki, JP;
Hiroshi Nishimoto, Kawasaki, JP;
Fujitsu Limited, Kawasaki, JP;
Abstract
The object of the present invention is to provide an optical amplifying apparatus for collectively amplifying wavelength-division multiplexed signal lights, which can perform amplification in response to input signal light, whose power level is within a wide input dynamic range, without saturating, and which suppresses the influence of the wavelength dependency of gain thereof. Thus, this optical amplifying apparatus is composed of: three optical amplifying portions connected in cascade; an optical attenuating portion for controlling the level of signal light output from the optical amplifying portion provided in the post-stage by regulating the power level of signal light input to the optical amplifying portion provided in the middle stage; and a dispersion compensation fiber provided between the middle stage and post stage optical amplifying. A gain of each of the optical amplifying portions is controlled to be constant by an AGC circuit. As a result of providing the optical amplifying portions in a three-stage constitution, the gain of optical amplifying portion provided in the first stage can be set at a low value. Thus, even when a signal light having a high power level is input, the first stage optical amplifying portion does not saturate. Consequently, the gain is controlled to be constant.