A vertical external cavity surface emitting laser (VECSEL) structure includes a heterostructure and first and second reflectors. The heterostructure comprises an active region having one or more quantum well structures configured to emit radiation at a wavelength, .sub.lase, in response to pumping by an electron beam. One or more layers of the heterostructure may be doped. The active region is disposed between the first reflector and the second reflector and is spaced apart from the first reflector by an external cavity. An electron beam source is configured to generate the electron beam directed toward the active region. At least one electrical contact is electrically coupled to the heterostructure and is configured to provide a current path between the heterostructure and ground.

The present invention relates to an active gain layer stack (21) for a vertical emitting laser device, the active gain layer stack (21) comprising a semiconductor material, wherein the semiconductor material is structured such that it forms at least one mesa (24) extending in a vertical direction. A transversally neighboring region (25) that at least partly surrounds said mesa (24) has a second refractive index (n.sub.2)At least part of said mesa (24) has a first refractive index (n.sub.1) and a part of the neighboring region (25) transversally adjacent to said part of the mesa (24) has second refractive index (n 2)Said first refractive index (n.sub.1) is higher than said second refractive index (n.sub.2) and a diameter in transversal direction of said mesa (24) is chosen such that a transversal confinement factor in the active gain layer stack (21) is increased. The present invention also relates to a laser device including such a stack, further to a method of operation of such a stack, and also to a method of manufacturing of such a stack. The VECSEL comprises a IV-VI semiconductor gain material grown on the lower mirror and an external cavity mirror. A plurality of mesa (22) may be grown on a single substrate (23). Anti-guiding is prevented by the lower refractive index of the surrounding material (25) improving the single transversal mode operation.

A vertical external cavity surface emitting laser (VECSEL) structure includes a heterostructure and first and second reflectors. The heterostructure comprises an active region having one or more quantum well structures configured to emit radiation at a wavelength, .sub.lase, in response to pumping by an electron beam. One or more layers of the heterostructure may be doped. The active region is disposed between the first reflector and the second reflector and is spaced apart from the first reflector by an external cavity. An electron beam source is configured to generate the electron beam directed toward the active region. At least one electrical contact is electrically coupled to the heterostructure and is configured to provide a current path between the heterostructure and ground.

A vertical external cavity surface emitting laser (VECSEL) structure includes a heterostructure and first and second reflectors. The heterostructure comprises an active region having one or more quantum well structures configured to emit radiation at a wavelength, .sub.lase, in response to pumping by an electron beam. One or more layers of the heterostructure may be doped. The active region is disposed between the first reflector and the second reflector and is spaced apart from the first reflector by an external cavity. An electron beam source is configured to generate the electron beam directed toward the active region. At least one electrical contact is electrically coupled to the heterostructure and is configured to provide a current path between the heterostructure and ground.