  By a tight-binding model, the interaction between linear atomic C chains
(LACCs) and short laser pulses was investigated. LACCs were proposed to be used
as a medium of laser whose wavelength can be continuously tuned in a range of
321~785 nm. This data should be more accurate than the previous result because
pure density functional theory calculation always underestimates the band gap.
According to the tight-binding model, the lifetime of conduction band (CB)
bottom is about 1.9~2.3 ns. The electrons pumped into the CB will quickly fall
to the band bottom in a time of ps due to electron$-$phonon interactions. The
above results indicate that LACCs are suitable for laser medium. By {\omega}+
2{\omega} dichromatic laser pulses, photocurrents can be generated in LACCs,
which can be applied as light$-$controlled signals.
