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:
Oct. 24, 2006
Filed:
Sep. 27, 2001
Takefumi Oguma, Tokyo, JP;
Takefumi Oguma, Tokyo, JP;
NEC Corporation, Tokyo, JP;
Abstract
The output monitor/control device is provided with: Mach-Zehnder circuitthat receives a light beam, branches the light beam into two light beams having a phase difference of 180°, and transmits each of the light beams, exhibiting a periodic optical transmittance-optical frequency characteristic a period of a frequency interval corresponding to a predetermined free spectral range; first and second photodiodes that each receive one of two light beams supplied from the Mach-Zehnder circuit; calculation circuitthat calculates a predefined discrimination formula for evaluating wavelength change of the light beam based on output currents of the photodiodes; and wavelength control circuitthat detects change in wavelength based on the calculation results by the calculation circuit and adjusts the wavelength to a set value. Mach-Zehnder circuitis adjusted in advance such that wavelengths to be controlled are included in a wavelength range that corresponds to the frequency range in which the optical transmittance-optical frequency characteristics curve of the Mach-Zehnder circuit changes steeply. The use of the optical transmittance-optical frequency characteristic of a Mach-Zehnder circuit in a wavelength monitor/control device enables accurate application to a wide range of wavelengths.