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. 08, 1983
Filed:
Sep. 25, 1980
Masafumi Seki, Tokyo, JP;
Nippon Electric Co., Ltd., Tokyo, JP;
Abstract
An optical isolator of reduced insertion loss and fabrication cost which comprises a nonreciprocal optically active element, such as a Faraday rotator, for 45.degree. rotation of polarization, a pair of lenses arranged on the opposite sides of the optically active element and a pair of birefringent crystal plates on the outer sides of the respective lenses having their 'principal planes' displaced 45.degree. from each other. The light beam passing through the isolator is most constricted at its opposite ends where the birefringent crystal plates are arranged and this minimizes the amount of offset required between any reflected light and the incident light at the entrance end of the isolator to prevent the reflected light from returning to the light source such as a semiconductor laser, thus enabling substantial reduction in thickness of the birefringent crystal plates. The use of two lens elements is effective to reduce the coupling loss of the isolator.