Laser manufacturers get industrious
During the go-go 1990s, telecom ambitions dominated the thoughts of the world s most capable laser-diode manufacturers. The handful of firms able to manufacture reliable 980 nm diode lasers supplied up to $500 million per year of pump-laser modules to the erbium-doped fiber amplifier (EDFA) market. Even leading lights of the industrial lasers arena like Coherent and Spectra-Physics scrambled to upgrade their capabilities to join the telecom gold rush because their traditional markets were puny in comparison.
The telecom boom resulted from huge, unsustainable over-investment. Perhaps less remembered is the disruptive effect of the EDFA, which attracted all that capital. The EDFA represents the difference between a single wavelength traveling 80 km over fiber between expensive optical-electrical-optical regenerators, and 160 wavelengths traveling 600 km at a radically lower transmission cost per bit.
As optical networks expanded from 4 to 16 to 160 wavelengths, the amount of optical pump power needed to fuel an EDFA grew proportionately. In a decade of whirlwind productivity, telecom-grade, single spatial-mode 980 nm diode laser power increased at a rate of 25% every year. Production efficiencies simultaneously enabled falling selling prices. A 90 mW, 980 nm pump module that sold for $7000 in 1994 now fetches less than $400, representing a 22% annualized price erosion. A 500 mW pump now sells below $1000, representing a more than 26% year-on-year decline in dollars per mW over that same period.
Such gaudy figures represent high tech as it should be. In an environment of rapid productivity improvement, the entire value chain shares the wealth and thrives. However, despite a newly buoyant telecom market, pump lasers are at an inflection point. Now that a single 500 mW pump laser services an entire EDFA gain stage, the previously unquenchable thirst for 980 nm power in a single fiber is largely sated. To continue to feed the EDFA value chain, pump-laser suppliers must either innovate along in a new, as yet undefined, technological direction, or face commoditization.
This conundrum resembles that recently faced by Intel. For years its technical roadmap focused on speeding the microprocessor clock rate - eventually saturating the PC market. But if your Dell has a 2 GHz processor does that leave you pining for 4 GHz? For Intel, the need for speed has diminished and been replaced by more useful things - wireless capability, reduced power consumption for extended laptop battery life, and a microprocessor core with more functionality. We ve barely heard a peep from marketeers about microprocessor GHz since.
For telecom pump lasers, a value-added lateral innovation like Intel s has not yet been identified. If a single diode could service multiple gain stages, demand would be rekindled for yet higher power devices delivering lower overall dollars per mW. However, EDFAs increasingly provide mid-stage wavelength add/drop agility, which decouples the amplification power needed in each stage. Independent and dynamic control of the amount of pump power reaching separate EDFA stages is lacking, and there is no foreseeable solution. Many have concluded the fundamental value metric of telecom pumps is destined to move from dollars per mW towards strictly dollars per laser, which smacks of commoditization. As a result, diode-laser research dollars are increasingly being redirected towards industrial markets that sustain long-term growth rates in excess of telecom s 6-8%.
Let s quickly recap the telecom-driven diode-laser era. Sleepy research teams that once nestled within large, corporate R&D labs landed at aggressive, medium-sized companies who provided them with unprecedented investment. The result was telecommunication-grade 980 nm pumps sustaining facet powers exceeding 50 MW/ cm2, representing perhaps the highest man-made energy density short of a nuclear explosion. The companies transferred their diode-laser assembly to Pacific Rim factories as a matter of survival, but are yet to earn sustainable returns.
Today, the few players capable of state-of-the-art volume diode-laser manufacture are lean, scalable and eager to unleash their highly refined technology into new growth markets. The market of choice is solid-state laser pumping for industrial applications. For a second consecutive decade, disruptive diode-laser advances will yield explosive consequences.
• In our next issue, Toby Strite describes how semiconductor laser-diode manufacturers will transform the industrial laser market.
