A laser apparatus may include a spectrum controller and a spectrum modulator. The spectrum controller may control a center wavelength and/or a bandwidth of a spectrum of a laser beam. The spectrum modulator may modulate the spectrum of the laser beam having the center wavelength and/or the bandwidth controlled by the spectrum controller. Thus, the laser beam may have the spectrum optimal for a semiconductor fabrication process. Particularly, the substrate may be accurately diced using the laser beam having the optimal spectrum.