Method for producing preform for polarization retaining optical fiber
CA 2048745 C · Owner: Sumitomo Electric Industries, Ltd. · Inventors: Takagi, Masahiro; Kanamori, Hiroo; Suganuma, Hiroshi
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
The present invention relates to a method for producing a preform for a polarization retaining optical fiber. The method comprises steps of making at least two holes symmetrically around a center axis of a preform comprising a core part and a cladding part which surrounds the core part. The method further comprises the steps of decreasing a diameter of one end of each hole, or connecting a glass tube to one end of the preform, the glass tube having a part with a smaller inner diameter near its end which is connected to said preform. The method further includes inserting a first glass rod, a stressing member and a second glass rod in this order from the other end of each hole or from an end …
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Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.
Why it's free to use
- Filed August 8, 1991 and granted September 30, 1997. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended August 8, 2011.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by August 8, 2013.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
Timeline
Timeline From CIPO dates
Sources & verification
Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.