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:
Mar. 09, 2010
Filed:
Nov. 29, 2006
Akihiko Isomura, Kawasaki, JP;
Jens C. Rasmussen, Kawasaki, JP;
Zhenning Tao, Beijing, CN;
Noriaki Mizuguchi, Kawasaki, JP;
Kenichi Kaburagi, Kawasaki, JP;
Akihiko Isomura, Kawasaki, JP;
Jens C. Rasmussen, Kawasaki, JP;
Zhenning Tao, Beijing, CN;
Noriaki Mizuguchi, Kawasaki, JP;
Kenichi Kaburagi, Kawasaki, JP;
Fujitsu Limited, Kawasaki, JP;
Abstract
Branches are grouped into a groupincluding first and second branches, and a groupincluding third and fourth branches. The signal after being passed through a dual pin photodiode in one branch included in the groupand being at the earlier stage of a CDR circuit is obtained. Also, from the later stage of the CDR circuit in the other branch in the groupis obtained. The obtained signals are passed through low pass filters, and an average value over a plurality of symbols is obtained. The signal from the earlier stage of the CDR circuit is multiplied by the signal from the later stage, and they are averaged. The obtained value reflects the phase difference of the two delay interferometers in the group. The groupis monitored by using the same method.