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:
Jun. 06, 1995
Filed:
Dec. 01, 1993
Hiroo Kanamori, Yokoyama, JP;
Akira Urano, Yokoyama, JP;
Tomonori Kashiwara, Yokoyama, JP;
Izumi Sankawa, Setagaya, JP;
Sumitomo Electric Industries, Ltd., Osaka, JP;
Nippon Telegraph & Telephone Corporation, Tokyo, JP;
Abstract
An object of this invention is to provide an optical filter which has higher mass-producibility and economy. This feature can be realized by doped a rare earth element into the region made of a glass material which can transmit light. In a case that Er and Tm are doped as the rare earth element into the region, a ratio .alpha..sub.Er /.alpha..sub.Tm between a contribution .alpha..sub.Er of Er to attenuation and a contribution .alpha..sub.Tm of Tm to attenuation is set in a range from about 1 to 1/25 for a 1.5 .mu.m band range, whereby attenuation in this wavelength range is retained above 50 dB/m to realize required cutoff function.