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:
Aug. 02, 2005
Filed:
Aug. 07, 2003
Takahisa Fujita, Tokyo, JP;
Toshio Sakane, Tokyo, JP;
Takahisa Fujita, Tokyo, JP;
Toshio Sakane, Tokyo, JP;
Sumitomo Osaka Cement Co., Ltd., Tokyo, JP;
Abstract
A method and device for stabilizing operation point and optical output of an external optical modulator. A low-frequency signal below a lower limit of signal frequency band of an input signal inputted to optical modulator is superimposed onto direct current bias. A low-frequency component included in detector output is extracted. On the basis of the low-frequency signal, output of the low-frequency component is normalized, and output-light of light source is controlled in accordance with normalized low-frequency component. Means of controlling optical output of light source, in control of output-light of light source, detects the output-light, compares the value of detected output-light to a standard value of primary optical output, and adjusts the output-light. The standard value is modified according to a ratio of primary value of normalized low-frequency component to a subsequent value, and means controlling optical output of light source is operated on the basis of modified standard value.