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:
Oct. 05, 1999
Filed:
Jul. 14, 1997
Yoshinobu Kubota, Kawasaki, JP;
Yasuhiro Omori, Kawasaki, JP;
Toshihiro Otani, Sapporo, JP;
Tomoyuki Itoh, Sapporo, JP;
Fujitsu Limited, Kawasaki, JP;
Abstract
An optical modulator for modulating light emitted from a signal light source has a substrate having electrooptic effect, an optical waveguide of a Mach-Zehnder type formed on the substrate, an electrode formed on the substrate to control light propagated in the optical waveguide, an interference light generating means for making radiation light radiated from the optical waveguide and signal light leaking from the optical waveguide interfere with each other to generate interference light, and emitting the interference light from an end surface of the substrate, a photo-detector for monitoring the interference light of the radiation light and the signal light, and a signal controlling circuit for controlling an operating point of the optical modulator according to a change of the interference light monitored by the photo-detector It is thereby possible to prevent degradation of a distinction ratio due to a shift of the operating point of the optical modulator so as to allow stable optical modulation, while facilitating a design of the mechanism of the optical modulator.