In case you missed it in the article, the transfer speeds are mentioned just two paragraphs prior to the one you cited:

Over the next three to four years, Kazansky said, SPhotonix aims to improve the data transfer speed of its technology from a write time of 4 megabytes per second (MBps) and read time of 30 MBps to a read/write speed of 500 MBps, which would be competitive with archival tape backup systems.