Expanding its Northwest footprint, Wave Broadband has acquired a fiber network operator that specializes in high-capacity links to public and business customers.

Wave Broadband’s parent, WaveDivision Holdings, paid $50 million for Black Rock Cable, which provides fiber connectivity in northwest Washington State.

Wave provides communications services in parts of Washington, Oregon and California. The two companies had been business partners. With the acquisition, Wave is picking up hundreds of large public and private sector commercial customers in government, medical, aerospace, communications, manufacturing and other regionally based industries.

Wave recently raised more than $1 billion in funding to support growth.

“This is a particularly important acquisition for Wave, as Black Rock’s proven expertise in dealing with commercial and wholesale clients greatly strengthens our enterprise business while extending Wave’s dark fiber network from the Canadian border down the West Coast to the San Francisco DMA,” said Steve Weed, Wave’s CEO.

“Connecting the Wave network to Black Rock’s thousands of miles of fiber infrastructure adds to Wave’s already asset-rich, high-capacity business and stands to enable better services for both new and existing customers,” he continued.

The company said the transaction, which closed at the end of 2012, will not impact Black Rock customers or employees. Services will continue without interruption as operations continue to be merged with Wave.

Wave was formed in 2003 by Weed. The company provides cable TV, high-speed Internet and phone services to nearly 400,000 residential and business customers in the communities, and surrounding suburbs, of the Seattle, Portland, San Francisco and Sacramento markets.