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:
Jun. 17, 2008
Filed:
Jan. 13, 2006
Yasuaki Hashizume, Yamato, JP;
Yasuyuki Inoue, Isehara, JP;
Takashi Saida, Sagamihara, JP;
Akio Sugita, Ibaraki, JP;
Yasuaki Hashizume, Yamato, JP;
Yasuyuki Inoue, Isehara, JP;
Takashi Saida, Sagamihara, JP;
Akio Sugita, Ibaraki, JP;
Nippon Telegraph and Telephone Corporation, Tokyo, JP;
Abstract
A planar lightwave circuit type variable optical attenuator with a small polarization dependent loss is provided. By setting the waveguide birefringence (absolute value) in first and second optical coupler sections equal to or greater than 3.5×10, the polarization mode coupling is made equal to or less than −25 dB, and the effect of the polarization dependence caused by the polarization mode coupling at the cross port of the first and second optical couplers is suppressed. In addition to or independently of this, the arm waveguide length can be designed to be equal to an integer multiple of the optical beat length obtained by dividing a used optical wavelength by the waveguide birefringence.