When JDS Uniphase (Nasdaq: JDSU) stood in the middle of Wall Street yesterday, frantically waving warning flags, Oplink Communications (Nasdaq: OPLK) investors looked the other way. Maybe they should have paid attention.

Today, Oplink's own fourth-quarter report is in, and the stock has joined JDSU in a double-digit fall over the past two days. Year-over-year sales growth of 12% and flat earnings largely met Street estimates, but a dismal outlook for the coming quarter sank the ship.

Meeting the top end of management's first-quarter guidance would mean missing revenue estimates by 6% and earnings targets by 36%. And even those unreachable Street projections describe year-over-year shrinkage in the first place.

For an optical-components specialist with 23% annual growth over the past five years and a 30% long-term annual growth projection pegged on it by analysts, that just won't do. Yet Oplink CEO Joe Kiu keeps a stiff upper lip: "As we continue to introduce building blocks for ROADM and flexible networks, Oplink is well positioned to gain market share."

Just not anytime soon. Kiu admits that "visibility is limited" and not at all helped by the uncertain economy. "The telecom equipment market is in its early stage of another upgrading cycle to higher capacity," he says, pointing past direct-systems clients Huawei and Tellabs (Nasdaq: TLAB) and passing the buck to foot-draggers at Verizon (NYSE: VZ), AT&T (NYSE: T), and China Mobile (NYSE: CHL). Slow orders from that rung of the networking industry are bad news for the whole ladder.

And once again, Mr. Market is taking this message the wrong way. If business is slow for both JDSU and Oplink, then why did Finisar (Nasdaq: FNSR) stay sanguine on Thursday and even jump on Friday? Granted, that stock has already seen lots of pain priced in over the past six months, but Finisar owners may still be in for a rude awakening when the company reports results -- and offers guidance -- in two weeks.

Keep an eye on the optical networkers: