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:
Jul. 12, 1988
Filed:
Jul. 09, 1987
Nobutaka Watanabe, Tokyo, JP;
Yuichi Odagiri, Tokyo, JP;
NEC Corporation, Tokyo, JP;
Abstract
In an optical isolator device using a Faraday rotator for permitting a forward light beam to pass therethrough but for preventing a reverse light beam from passing therethrough, two Faraday rotators are used in a cascade-connection in order to improve the temperature characteristic of the isolation over a wide temperature range. One of two Faraday rotators is prepared to have the Faraday rotation angle of 45.degree. for a wavelength shorter than the intended wavelength .lambda..sub.0, while the other having the Faraday rotation angle of 45.degree. for a wavelength longer than .lambda..sub.0. A polarizer and an analyzer are disposed on opposite ends of one of the rotators at a rear stage and prevent the reverse light beam from passing therethrough. Another polarizer and another analyzer can further be disposed at opposite ends of the other front stage rotator so that two isolators are arranged in a cascade-connection. The rotation angular deviation of the light beam caused at the front stage rotator by the temperature variation is cancelled by the rotation angular deviation caused at the rear stage rotator by the same temperature variation.