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. 27, 2003
Filed:
Oct. 23, 2001
British Telecommunications public limited company, London, GB;
Abstract
An arrayed waveguide grating [WDG] comprises I/O slabs ( ) interconnected by a grating region ( ). The grating region ( ) comprises many, e.g. at least 25 and preferably 50 to 500, individual cores ( ), which have different lengths so as to provide wavelength selectivity by causing phase changes in light conveyed between the I/O slabs ( , ). There are bends ( ) for providing the different lengths and, to improve optical guidance round the bends, empty (R.I.=1) grooves ( ) are located adjacent to the inside ( ) and outside radii ( ) so that the evanescent fields extend into the grooves ( ). In order to keep the dimensions small, which improves the optical accuracy, tight bends (preferred radii of curvature of less than 2 mm and especially less than 500 &mgr;m) are desirable. The grooves conveniently have tapered ends and they extend into straight portions adjacent to the bends. The WDG is preferably implemented in silica glass with dopants to adjust the refractive index and/or the melting point.