It was time for a party for some former Nortel workers in Ottawa on Thursday.

About 1,200 of them officially became employees of American-owned Ciena last week.

The company marked the occasion by throwing a bit of a party at Scotiabank Place. In all, nearly 1,600 people attended, including 200 workers from Montreal and 200 more who already work for Ciena in Ottawa.

CEO Gary Smith said the takeover of Nortel's optical division for $774 million has doubled the size of the company.

"Seventy-five per cent of the world's telecom carriers are now using Ciena equipment," said Smith.

"We are number one in North America and number two in the rest of the world. We are a growth company."

Smith told CTV Ottawa that operations in Ottawa are key to future success.

"The Ottawa research operation is crucial to our plans going forward and we have committed to a 10-year lease. We are here for the long term and we expect there will be significant expansion," he said.

There were plenty of smiles from employees as they entered Scotiabank Place on Thursday where they were given a new name pin and corporate swag.

There was also an obvious change of mood among those who have endured several years of uncertainty while working at Nortel.

Several workers told CTV Ottawa workplace morale has improved significantly. Some say the stability might even encourage innovation in the company's labs.

One 30-year veteran of Nortel said it was a "bittersweet day," describing it as the end of one company and the beginning of a new chapter.

About 90 per cent of Nortel's employee base was hired by Ciena. The company has merged product lines and Smith says it will be another year or two before the integration is complete.

Ciena estimates it will cost about $180 million to execute the change over. Now, Ciena has more employees outside the U.S. than inside the country – a fact Smith said made him proud.

With a report from CTV Ottawa's Paul Brent