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. 07, 2010
Filed:
Dec. 12, 2005
Akira Miura, Kawasaki, JP;
Kentaro Nakamura, Kawasaki, JP;
Hiroshi Onaka, Kawasaki, JP;
Yuichi Akiyama, Kawasaki, JP;
Hiroki Ooi, Kawasaki, JP;
Jens Rasmussen, Kawasaki, JP;
Takeshi Hoshida, Kawasaki, JP;
Akira Miura, Kawasaki, JP;
Kentaro Nakamura, Kawasaki, JP;
Hiroshi Onaka, Kawasaki, JP;
Yuichi Akiyama, Kawasaki, JP;
Hiroki Ooi, Kawasaki, JP;
Jens Rasmussen, Kawasaki, JP;
Takeshi Hoshida, Kawasaki, JP;
Fujitsu Limited, Kawasaki, JP;
Abstract
A data modulator unit generates a DQPSK optical signal in accordance with a data signal. A phase shift unit provides a phase difference of π/2 between a pair of arms. A photodetector converts an output signal of the data modulator unit into an electrical signal. A filter is a low-pass filter with a cut-off frequency lower than a symbol frequency, and filters an output signal of the photodetector. A monitor unit detects power of an output signal of the filter. A phase difference control unit adjusts the amount of phase shift in the phase shift unit so as to minimize power of an output signal of the filter.