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. 10, 1998
Filed:
Dec. 27, 1995
Applicant:
Inventor:
Tsutomu Tajima, Tokyo, JP;
Assignee:
NEC Corporation, Tokyo, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
H01S / ; H04L / ; G02F / ;
U.S. Cl.
CPC ...
359249 ; 359177 ; 359183 ; 330 97 ;
Abstract
A DC bias controller for an optical modulator includes an optical modulator, a demultiplexer, and a controller. The optical modulator intensity-modulates input DC light by a digital main signal superposed with a DC voltage to convert the DC light to an optical signal. The demultiplexer demultiplexes the optical signal from the optical modulator into output signal light and monitor signal light. The controller detects a change in modulation characteristics of the optical modulator on the basis of the monitor signal light from the demultiplexer to control a value of the DC voltage superposed on the digital main signal.