Ciena Corp. (CIEN) has gotten the official green light to bid for Nortel Networks’ optical networking business.

Bankruptcy judges in the United States and Canada on Thursday approved Ciena’s “stalking horse” bid of $521 million.

At first, the judges did not like Ciena’s specifics but the company made some concessions such as agreeing to offer jobs to at least 2,000 Nortel workers. That would almost double the size of Ciena’s workforce.

Nortel’s optical networking unit is probably its most-prized, not to mention its most-profitable, division.