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. 18, 2003
Filed:
Nov. 29, 1999
Tsutomu Tajima, Tokyo, JP;
NEC Corporation, Tokyo, JP;
Abstract
A wavelength control circuit includes a temperature control loop monitoring the ambient temperature of an LD device and driving an electronic heating and cooling device so that the temperature is constant on the basis of a difference signal between a signal value corresponding to the temperature and a reference signal. In a wavelength control loop, the wavelength of a light signal from the light emitting device is monitored by a wavelength monitor and the electronic heating and cooling device is controlled so that the wavelength is uniform. At power on, the temperature is controlled by the temperature control loop to control LD device wavelength. After the temperature control loop is stabilized, a control is performed with both the temperature control loop and the wavelength monitor.