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. 21, 1989
Filed:
Mar. 20, 1986
Masataka Shirasaki, Kawasaki, JP;
Hirochika Nakajima, Kawasaki, JP;
Fujitsu Limited, Kawasaki, JP;
Abstract
Spatial phase modulating transparent masks comprising two or more portions having two different optical paths and their production processes are disclosed. The transparent masks are particularly useful as an exposure mask in the production of phase-shifted, distributed feedback (DFB) semiconductor lasers for a single-mode operation. A process for the formation of phase-shifted diffraction gratings or corrugations which comprises exposing a substrate, through the above transparent mask, to exposure radiation is also disclosed. According to the present invention, the phase-shifted diffraction gratings can be easily and directly produced with a high accuracy and reliability.