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. 26, 1998
Filed:
Sep. 05, 1997
Tamayo Hiroki, Zama, JP;
Canon Kabushiki Kaisha, Tokyo, JP;
Abstract
A semiconductor laser includes a distributed feedback semiconductor laser structure having a plurality of regions. The regions are electrically separated from each other. A phase shift section is provided in a grating in one of the regions. In the semiconductor laser, .alpha. parameters for transverse electric (TE) and transverse magnetic (TM) polarization modes, in the vicinity of threshold currents for the TE mode and the TM mode, are made different from each other. An .alpha. parameter is defined by 4.pi./.lambda..multidot.(dn/dN)/(dg/dN) where .lambda. is a Bragg wavelength, n is an effective refractive index, N is an injection carrier density and g is a gain for each of the TE mode and the TM mode.