Spectral beam combined laser system and method

A spectral beam combined laser system comprising an optical gain element array, a transform element having a focal plane, a diffraction element and a reflecting element, wherein said optical gain element array, said transform element, said diffraction element, and said reflecting element are sequentially positioned in an optical path, wherein

• said optical gain element array comprises a plurality of gain elements that radiate laser beams having different wavelengths;
• said transform element is positioned such that the focal plane of the transform element is at a reflecting rear facet of the optical gain element array, and the transform element focuses and spatially overlaps the laser beams received from said optical gain element array at said diffraction element;
• said diffraction element is positioned at the focal plane of the transform element and diffracts the laser beams spatially overlapped by the transform element to spectrally combine the laser beams to the reflecting element;
• and
• said reflecting element is positioned to intercept a portion of the laser beams diffracted by the diffraction element and feedback the intercepted laser beams to the optical gain element array in a V-shaped off-axis external cavity with an off-axis reflecting angle, wherein said V-shaped off-axis external cavity with the off-axis reflecting angle is formed between the reflecting element and the optical gain element array such that the laser beams subjected to feedback by the V-shaped off-axis external cavity are output underneath the reflecting element as output laser beams by said diffraction element.