The present invention relates to an extended cavity
semiconductor laser device comprising an array of at least two
semiconductor gain elements (20, 21), each of said
semiconductor gain elements (20, 21) comprising a layer structure (1) forming a first end mirror (2) and an
active medium (3). A
coupling component (22) inside of the device combines fundamental
laser radiation emitted by said array of semiconductor
gain elements (20, 21) to a single combined
laser beam (25). A second end mirror (23) reflects at least part of said single combined laser beam (23) back to said
coupling component (22) to form extended cavities with the first end mirrors (2). Due to this coherent
coupling of several extended cavity semiconductor lasers a
single beam of the fundamental
radiation is generated with increased intensity, good beam profile and narrow spectral
band width. This beam of increased intensity is much better suited for
frequency conversion via upconversion or via
second harmonic generation than the individual beams of the array of extended cavity semiconductor laser components. The efficiency of
frequency conversion is therefore greatly enhanced.