A multi-wavelength external cavity laser system is disclosed, wherein an array of individual laser elements is placed in a shared laser cavity for all wavelengths that is defined by a free space grating, an optional reflector, and a single relay lens. Laser radiation from the cavity can be externally modulated at each wavelength and outputted as an overlapping beam having substantially all the wavelengths produced by the laser elements through a single fiber or as an array of wavelength-separated beams. A modular design facilitates the addition and/or repair of individual or several channels.