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. 28, 2002
Filed:
Jun. 07, 2000
Sycamore Networks, Inc., Chelmsford, MA (US);
Abstract
An apparatus for measuring the optical-signal-to-noise ratio (OSNR) of an optical system is adapted to function in single channel or in multi-channel wavelength division multiplexed optical communication systems. An optical signal spectrum and a center frequency characterize the optical signals. A narrow-band notch filter, realized by an in-fiber Bragg grating, is utilized to remove a component of the signal so the remaining signal can be measured. When multiple channels are present, a bandpass filter is used to select the part of the multiplexed signal to be measured. Both the narrow-band notch filter and the bandpass filter can be tunable to further extend the capabilities of the system. Two detectors are utilized with the power in the channel being measured by a low-gain detector and the power in the noise being measured by a high-gain detector. A processor receives the detector outputs, calculates OSNR, and controls the tunable components.