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:
Dec. 08, 1998
Filed:
Mar. 13, 1997
Kazuto Imai, Sapporo, JP;
Tsukasa Takahashi, Sapporo, JP;
Fujitsu Limited, Kawasaki, JP;
Abstract
An optical power monitor device capable of monitoring optical power with the influence of optical crosstalk eliminated, and an optical amplifier and an optical transmitter each having the monitor device. The monitor device is applied to a light source for outputting first and second beams, for example. The first beam is divided into first and second branch beams by a beam splitter. The first branch beam is supplied to a first photodetector. The first photodetector outputs a first signal having a level corresponding to the power of the first branch beam. The second beam from the light source is supplied to a second photodetector. The second photodetector outputs a second signal having a level corresponding to the power of the second beam. The first and second signals are supplied to a first subtracter. The first subtracter outputs a first error signal corresponding to the difference between the first and second signals. The first signal and the first error signal are supplied to a second subtracter. The second subtracter outputs a second error signal corresponding to the difference between the first signal and the first error signal. Thus, the second error signal is obtained by using the first and second subtracters to thereby cancel a noise component caused by optical crosstalk and therefore eliminate the influence of optical crosstalk from the second error signal.