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:
Feb. 20, 2001
Filed:
Dec. 01, 1999
Keiro Komatsu, Tokyo, JP;
NEC Corporation, , JP;
Abstract
A multiple-wavelength light source has a plurality of semiconductor laser devices, a plurality of optical waveguides for leading laser beams from the semiconductor laser devices to respective desired paths, and a plurality of diffraction gratings as external cavities for the semiconductor laser devices. The multiple-wavelength light source can output laser beams of respective wavelengths determined by structural details of the diffraction gratings. The multiple-wavelength light source also has an optical combiner for multiplexing the laser beams from the semiconductor laser devices into a laser beam, an optical wavelength multiplexer/demultiplexer for demultiplexing the laser beam from the optical combiner into a plurality of laser beams of respective desired wavelengths, and outputting the laser beams, a plurality of photodetectors for detecting the laser beams from the optical wavelength multiplexer/demultiplexer and outputting voltages depending on respective detected laser beam power levels, a plurality of heaters disposed near the diffraction gratings for varying temperatures of the diffraction gratings, and a heater current control circuit for supplying currents to the heaters for maximizing the output voltages from the photodetectors.