31 May 2006
Alfalight's design for an uncooled diode laser, based on WST - Wavelength Stabilized Technology - maintains a precise wavelength over a 30ºC temperature drift
Diode laser developer Alfalight, based in Madison, WI, US, has introduced its Wavelength Stabilized Technology (WST) diode lasers in two versions: a 2 W fiber-coupled package and a 2.5 W chip-on-carrier model.
To maintain its wavelength, a conventional laser diode needs to be cooled so that its temperature does not vary by more than 1ºC. But with the WST grating design, the laser's temperature may drift by up to 30ºC and the wavelength will only change by 0.7 nm per 10ºC.
A monolithically integrated, holographically written grating on the diode laser determines and maintains the output wavelength at 976 nm. This reduces thermal effects by a factor of five as well as reducing the linewidth by a factor of 10. Moreover, energy consumption is reduced by a factor of three compared with a thermally-controlled pump laser.
Alfalight developed Wavelength Stabilized Technology under a contract with the U.S. Air Force Research Laboratory as part of the agency's Laser Development Engineering and Research Applications (LADERA) program.
This stabilization method is an integral part of the manufacturing process and defines the output wavelength with greater precision compared with other methods of stabilization without significant additional cost, the company claims.
The developer has initially focused on the important 976 nm wavelength required to pump narrow transition in ytterbium-doped fiber lasers. This method has been demonstrated in diode laser bars and is applicable to other wavelengths.
The diodes are available fiber-coupled with a 2.0 W output in a 6-pin uncooled package with 105 µm/0.15NA fiber, or with 2.5 W in a chip on carrier packages.
"Historically, single mode diode laser (or distributed feedback laser) gratings have been available for some time, although not in millimeter devices," said Rob Williamson, marketing director.
"This was because a common belief was that such a model would not function properly. It's only recently that we have realized that the technology could work with multimode lasers."
"These are the first entries in a range of products based on our WST design, which is aimed at precision pumping of fiber and solid-state lasers. So far we have made small samples but making orders in volume could be expected over the next couple of months."
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