PETALUMA -- Cyan Optics, the Petaluma maker of optical packet systems for telecom carriers, scored a fourth round of equity funding. The company received $22 million according to a regulatory filing.

Cyan previously received $17.5 million in December 2007 and $8.8 million in June 2009. The company, founded by telecom veteran Mike Hatfield in 2006, is backed by Nortwest Venture Partners, Azure Capital Partners and Tenaya Capital.

“We’re obviously pleased to have the continued support of our existing investors and the addition of two new investors with this latest round,” said Mr. Hatfield. He did not identify the new investors.

Although Cyan declined to disclose revenues in the U.S. Securities & Exchange Commission filing in late December, the company has about 20 carrier, cable and data center customers for its optical transport and management systems, which lower costs and simplify the movement of traffic over Ethernet.

Its latest platforms “will help make service providers’ operations fundamentally more efficient. This is one of the best new products I’ve seen in years,” said Infonetics Research analyst Michael Howard.

Cyan has 60 employees in its Petaluma headquarters. The company is currently hiring network engineers, according to its Web site.