Among the many different sessions at last month's Conference on Lasers and Electro-Optics (CLEO) in Baltimore, MD, was a celebration of the semiconductor laser. Developed more than 40 years ago at four different labs by Robert Hall, Nick Holonyak, Marshall Nathan, and Robert Rediker, the details of the technology underlying the laser diode were first published in 1962. All four scientists gave talks at CLEO plenary presentations that served to highlight the significance of their invention. Not only has the laser diode become ubiquitous in our everyday lives—from CD players to telecommunications—but it has also been an enabling technology for other types of laser systems, most notably diode-pumped solid-state devices. Diode pumping is also fundamental to fiber lasers, which were much in evidence at CLEO and at another recent conference: the Solid-State and Diode Laser Review Conference held in Albuquerque, NM, in May (see p. 15 and p. 21). Today's semiconductor laser technology has evolved to encompass a multitude of materials systems and output wavelengths, power levels, and applications. But all of them can trace their roots back to the original 1962 invention.
The impact of the semiconductor laser on other laser systems has been significant. An ultrafast laser, for example, once filled an entire lab and required constant attention from a high-level technician. Now though, in no small way thanks to the impact of diode pumping, these systems are more compact and are reliable enough to operate outside the lab in the real world of materials processing. And while the cutting of high explosives—which is featured on this month's cover—may seem a rather esoteric application, it does serve to illustrate the very real advantage of femtosecond pulses when cool cutting is required. There are, of course, a number of less esoteric applications some of which are discussed in the accompanying feature on p. 69.
The laser diode was invented in North America but it's worth mentioning that the first high-volume application of the device—as a source for audio CD players—was actually centered in Japan. Even today, optical storage is still the largest single laser market, although device production is now scattered throughout Asia. That region is one of the most dynamic optoelectronic locations on the planet, as executive editor Conard Holton notes in our special Asia Supplement, which follows p. 80.
