Ciena Corp. yesterday laid off an additional 650 people, or 22 percent of its workforce, because of dramatically slower sales in the fiber-optics sector. ... Even as the rest of the economy shows signs of recovery, the telecommunications sector remains in shambles. ... Spending is down about 40 percent ... Ciena's main problem ... is its lack of focus. ... "The industry has gone through a precipitous decline that has taken everybody by surprise."