LINTHICUM, Md., April 2 – Ciena Corp. has completed its purchase of optical-switching systems company Cyras Systems Inc. for about $1.1 billion in Ciena stock – less than half the value of the deal when it was first announced. Ciena's purchase of privately held Cyras for 27 million shares of common stock was first valued at $2.6 billion on Dec. 19, but by Thursday's close Ciena's stock had lost 57 percent of its value, thus cutting the value of the deal.