Yes. In fact, we have already begun to do so in the radio-wave portion of the spectrum. The powerful radar beacons we emit are very narrow bandwidth and high power signals. If you calculated the luminosity of these beacons and compared this emitted power with what the sun produces at the same wavelengths and bandwidths, we already out-power the spectrum of the sun. Visit the SETI web site to read more about this. To modify the infrared or optical spectrum is much harder, BUT, buy using lasers tuned to very narrow (a few hertz) bandwidths, we stand another good chance of out-performing the spectral line emission of the sun. We can, however, never compete with the raw, broadband power emitted by the entire solar photosphere's black body emission.
All answers are provided by Dr. Sten Odenwald (Raytheon STX) for the
NASA IMAGE/POETRY project.