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:
Jan. 12, 1999
Filed:
Aug. 22, 1997
Hideaki Sugiya, Kawasaki, JP;
Yuji Tamura, Sapporo, JP;
Fujitsu Limited, Kawasaki, JP;
Abstract
An optical power monitor for an optical signal having a signal spectrum superimposed on a noise spectrum. Typically, the optical power monitor includes an optical coupler, first and second optical band-pass filters, first and second photodetectors, and an operating unit. The optical coupler branches the optical signal into first and second beams. The first optical band-pass filter has a first pass band including the signal spectrum, and the first beam is supplied to the first optical band-pass filter. The second optical band-pass filter has a second pass band including the signal spectrum and narrower than the first pass band, and the second beam is supplied to the second optical band-pass filter. The first photodetector receives the first beam passed through the first optical band-pass filter, and the second photodetector receives the second beam passed through the second optical band-pass filter. The operating unit calculates the power of the optical signal according to output signals from the first and second photodetectors. Since the first and second optical band-pass filters have different pass bands, the power of the optical signal relating to the signal spectrum can be precisely monitored with no effects of the noise spectrum.