Clobbered by the telecom spending crunch, Ciena ( CIEN) showed its upstart mettle Thursday, vowing that its technological advantage will help it bounce back. But the company offered little evidence that it will get off the floor anytime soon.The optical-equipment maker reported an even bleaker than expected third quarter Thursday morning, posting a 42% sequential sales decline and a stunning 88% plunge from year-ago levels. The company also posted a third-quarter loss that was more than three times the size of its pitiful $50 million top line. Executives on a call with analysts doggedly insisted that the company is "guardedly optimistic" about the current quarter. But investors can hardly be expected to take heart in those remarks, considering that the big telcos that do most of the industry's spending continue to tighten their belts. Ciena dropped 20 cents, to $4.29.