Aluminum-free large-optical-cavity diode laser generates 8 W at 980 nm
More than 8 W of 980-nm continuous-wave (CW) output power from the front facet of a
100-?m-aperture aluminum-free semiconductor laser has been obtained by researchers at the Reed Center for Photonics at the University of Wisconsin-Madison (Madison, WI) with
collaborators at the David Sarnoff Research Center (Princeton, NJ) and Coherent Laser Grou¥(Torrance, CA). This power is the highest CW output reported from any type of 100-?m-stri¥semiconductor laser, according to Dan Botez, director of the Reed Center for Photonics. The output was produced from devices without nonabsorbing mirrors; Bote¥expects that depositing zinc selenide films on oxide-free mirror facets could increase the output power above 10 W (see Laser Focus World, April 1996, p. 15).
To reduce the internal loss and double the transverse spot size of a 980-nm indium
gallium arsenide/indium gallium phosphide/gallium arsenide laser, the researchers increased the optical-cavity thickness. Low internal loss enabled the researchers to apply the Obroad waveguideO concept to the design; that is, a reduction of the optical confinement factor of the laser can be offset by increasing the cavity length. Thus, a cavity as long as 4 mm permits a broad-waveguide (~1 ?m) device with large transverse spot size to produce higher output power with little penalty in threshold-current density or efficiency. Bote¥says these high-power wide-aperture aluminum-free lasers are needed for applications such as pumping solid-state lasers and medical therapy.