Résumé
We report on the highly coherent modeless broadband continuous wave operation of a semiconductor vertical-external cavity-surface-emitting laser. Its design is based on a frequency-shifted-feedback scheme provided by an acousto-optic frequency shifter inserted into the cavity. Chirping the optical wave inside the cavity leads to the elimination of the traditional spectral resonances occurring in usual laser cavities, leading to a wideband (>330GHz here) continuous spectrum. The light is of high coherence concerning the transverse mode and the polarisation state, as well as in the time domain (time coherence approximate to 19 mu s, like a 1MHz DFB) in spite of its wideband emission.