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. 17, 2004
Filed:
May. 29, 2001
Poul-Erik Hansen, Farum, DK;
Ibsen Photonics A/S, Farum, DK;
Abstract
An improved technique of exposing a photoresist through a grating mask reduces the occurrence of overlapping gratings and also avoids distortions in the exposed mask when there is a gap between the contact mask and the photoresist layer. The technique is particularly well suited to forming Bragg gratings on semiconductors and other materials that are used for wavelength selection in, for example, optical communications applications. The technique employs a phase grating held close to, but out of contact with, the photoresist layer. Amongst the advantages provided by the present invention is that the requirements of the permissible thickness of the photoresist layer suitable for writing high visibility gratings are relaxed, thus reducing the complexity and costs for processing the substrate.