U.S. Reissue Patent No. RE42,521, reissued on July 5, 2011 to Capella Photonics, Inc. of San Jose, CA, discloses a wavelength-separating-routing (WSR) apparatus that can be used to construct a dynamically reconfigurable optical add-drop multiplexer (OADM) for wavelength-division multiplexing (WDM).
Fiber optic networks commonly support many data channels, each having its own wavelength. An optical add-drop multiplexer (OADM) is used to receive all of these data channels, to selectively remove (or drop) the one of interest (e.g., to read the information on that data channel), and/or to selectively add a data channel to the data traffic stream. The OADM therefore allows the data stream to be manipulated without disrupting the overall data traffic flow. According to the ’521 reissued patent, conventional OADMs are difficult to dynamically reconfigure, require stringent fabrication tolerances and alignments, are susceptible to thermal and vibration disturbances, and require power or gain equalization. The ’521 reissued patent discloses a polarization diversity arrangement to overcome polarization-dependent effects and an array of micromirrors that can be actuated to pivot about two axes to selectively reflect certain data channels to selected output ports and to control the power at these ports.
According to its website, Capella was founded in 2000 and is a leading provider of wavelength selective switches for use in ROADM and optical cross connects, having “an extensive intellectual property portfolio with 27 patents issued and over 30 pending.” Earlier this year, Capella closed a $20 million financing which is earmarked for expanding and strengthening the company’s presence in the ROADM market “which is expected to grow to $1.8 billion over the next four years.”
The ’521 reissue patent was actually reissued by the USPTO twice. Reissue is a mechanism through which a patentee can correct mistakes in an issued U.S. patent that if uncorrected, would make the patent partially or wholly invalid. Examples of such errors are not naming the correct inventors, or having claims that do not encompass the full scope of the invention. If a reissue application seeks to broaden the scope of protection, it must be filed within two years of the original patent’s issuance. Reissue applications that seek to narrow the scope of protection (e.g., in view of newly discovered prior art) or to correct other mistakes can be filed at any time during the lifetime of the patent.
To start the reissue process, the patentee has to relinquish the patent back to the USPTO and must identify an error that is sought to be corrected. The USPTO will then review the application again, and if permissible under the patent laws, will make the correction. Once corrected, the patent is “reissued,” but it still has the same expiration date as did the original patent.
The subject matter claimed in the ’521 reissue patent originally issued as U.S. Pat. No. 6,760,511 in July 2004. Five months later, Capella relinquished the patent to the USPTO with a reissue application that sought to correct the inventorship of the patent. Apparently, the original patent omitted one of the actual inventors (incorrect inventorship would have made the patent invalid). After almost three years, the USPTO granted Reissue U.S. Patent No. RE39,515. Three years later, Capella again sought to correct an error, this time because some of the claims were too broad in view of the prior art, and to correct some typographical errors in the claims that affected their clarity. This time, it took the USPTO only one year to grant the reissue, resulting in the ’521 reissue patent.
The claims of a reissue patent show the changes that were made during the reissue process: deletions are shown between two bolded brackets (e.g., [deleted text]) and additions are shown as italicized text (e.g., additional text). Take a look at claim 1 at the top of this blogpost to see how it was narrowed by including additional features that were not in the claim as originally issued.