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:
Nov. 20, 2007
Filed:
Aug. 08, 2003
Haijun Yuan, Fremont, CA (US);
Yongsheng Liu, San Jose, CA (US);
Xingzhong Zhao, Newark, CA (US);
Avanex Corporation, Fremont, CA (US);
Abstract
A liquid crystal optical performance monitor is described that employs a liquid crystal tunable filter for receiving a P-polarization beam and a rotated S-polarization beam from a C-polarizer. The rotated S-polarization beam from a birefringent crystal in C-polarizer propagates through a waveplate which rotates the polarization by 90 degrees, resulting in the rotated S-polarization beam having the same polarization orientation as the P-polarization beam. The liquid crystal tunable filter therefore receives just the P-polarization orientation. The C-polarizer and a small beam collimator are rotated so that the polarization orientation of the P-polarization beam and the rotated S-polarization beam matches the orientation of the LC inside the LC cavity of the LC tunable filter. In a first embodiment, the liquid crystal optical performance monitor is implemented with a photodiode. In a second embodiment, the liquid crystal optical performance monitor is implemented with a bi-cell photo diode.