New technologies can make the old ones better

Technology transitions are pretty common in optoelectronics—the gradual displacement of CRTs by flat-panel displays as computer monitors, for example, or the use of fiberoptics instead of copper to carry phone conversations. Historically, the rate of uptake of a new technology has been hard to forecast, and the predictions of pundits who should know better are often quite wrong. Ironically, the emergence of a new technology can actually drive refinements to the old one, causing it to become even more entrenched. Hence, the ubiquitous computer hard disk—based on magnetic-storage technology that has been, according to many, "doomed" for years—is still going strong. And prospects are dim for optical methods to displace it as the primary storage device on PCs.

Some 15 years ago, helium-neon lasers were also purportedly destined for a quick trip to oblivion as the ascendancy of semiconductor lasers pushed them aside. In fact, it took longer than almost anyone expected for laser diodes to completely replace HeNes in many applications because of aggressive cost engineering on the part of laser makers. Now skip forward a few years to see a similar scenario with low-power argon-ion lasers. The first commercial green-emitting diode-pumped solid-state devices supposedly heralded the imminent demise of low-power argon lasers. But, although some of their earlier applications moved on to other lasers, new ones have emerged that find the low-cost, high-quality output of an ion laser irresistible (see p. 147).

It was not so long ago that optical lithography was expected to reach its limit in terms of integrated-circuit fabrication when feature sizes dropped below 1 µm. As a result, various alternatives are being investigated, such as electron-beam lithography. Now, though, chips routinely are made with 0.18-µm features using optical lithography. The excimer laser is one reason for the ongoing use of optical lithography. Apart from being a convenient source of ultraviolet light, its success results largely from the significant investment by the laser makers and their suppliers to make the excimer a reliable production tool (see p. 73).

Of course, some technologies, even those based on unique ideas, never make it. An 1881 patent describes a central home-lighting system using hollow light pipes to guide light from a common source to illuminators in each room. In fact, though not in common use for this purpose, optical fiber has proven to be a much more efficient light pipe than hollow waveguides (see p. 81).