Fabrication of fused silica optics for high-powered Nd:YAG laser applications commonly employs grinding and
polishing processes to generate smooth, specular surfaces. The industry often describes such surfaces as "laser quality"
after assessment against such gauges as surface roughness or scratch-dig standards; however, surfaces deemed
acceptable have performed variably when actually exposed to high-powered laser illumination. Traditional processes to
prepare such surfaces have often relied on rules of thumb, but we have found a convenient and simple method to help the
fabricator optimize expressly for a desired performance metric, that of low subsurface damage. Subsurface damage often
has immediate impact on susceptibility to destruction by high-power laser illumination, and we find that this damage is
not universally related to surface roughness. In addition, we show that surface roughness measurements may vary
depending on the measurement method used, such as white light interferometry (WLI), variable angle spectroscopic
ellipsometry (VASE) or atomic force microscopy (AFM).
We report batch-processed, totally planar, vertical-cavity top surface emitting GaAs/AlGaAs laser devices and arrays. Different size devices are studied experimentally. We measure continuous-wave threshold currents down to 1.7 mA and output powers > 3.7 mW at room temperature. We also discuss interesting characteristics such as differential quantum efficiencies exceeding unity and multi-transverse mode behavior. An array having 64 X 1 individually-accessed elements is characterized and shown to have uniform room-temperature continuous-wave operating characteristics in threshold current approximately equals 2.1 +/- 0.1 mA, wavelength approximately equals 849.4 +/- 0.8 nm, and output power approximately equals 0.5 +/- 0.1 mW.
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