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:
May. 12, 1998
Filed:
Oct. 31, 1996
Makoto Shibutani, Tokyo, JP;
Katsumi Emura, Tokyo, JP;
NEC Corporation, Tokyo, JP;
Abstract
An optical transmission system of an N : 1 or an N:N type is provided, in which there is no deterioration caused by beat noise between signals. A plurality of optical modulators are cascaded in an optical fiber transmission path having a light source and a plurality of light receivers connected to two respective ends of the optical fiber transmission path, and carrier waves having frequencies respectively different are applied to the optical modulators. This enables the light receivers to receive a radio frequency signal in which the carrier waves are frequency-multiplexed. The light receivers receive only the signal beam so that there is no occurrence of beat noise. In another arrangement, at the optical network terminal, a part of a signal beam is split and the split beam is intensity-modulated responsively to carrier waves by an optical modulator and, thereafter, is combined again to a passing beam. It is possible to obtain at the signal beam receiver a received signal in which carrier waves from respective optical network terminals are frequency-multiplexed. This prevents occurrence of inter-modulation distortion in the cascaded optical modulators.