  A search for laser light from the directions of Alpha Centauri A and B was
performed by examining 15362 optical, high-resolution spectra obtained between
2004 and 2018. None of the spectra exhibit laser emission lines. The threshold
was 10% of the continuum intensity of the spectra of both stars at all
wavelengths between 3850 and 6900 {\AA}. This search would have revealed
optical laser light from the directions of Alpha Cen B if the laser had a power
at least 1.4 to 5.4 MW (depending on wavelength) and was positioned within the
1 arcsecond field of view (projecting to 1.3 AU), for a benchmark 10-meter
laser launcher. For Alpha Cen A, the laser power must be 3 times greater for
detection. Lasers of smaller aperture would also have been detected but would
require more power. Considering all optical surveys, a growing desert is
emerging in the search for extraterrestrial technology.
