Patent ID: 7623556

Claim:
A frequency multiplier device comprising, or associated with, a laser source of a pump radiation at a frequency F, the device including a ring optical cavity and a non-linear optical member oriented in the cavity, wherein the optical member comprises a first optical member for satisfying the phase-matching or quasi-phase matching condition for the degenerate non-linear conversion F2 *F/2, and a second optical member for satisfying the phase matching condition for the non-linear conversion F+F/2 3/2*F, the cavity comprising a plurality of mirrors having a relatively high reflectivity at least for the radiation at frequency F/2, and suitable for extracting from the cavity the radiation at frequency 3/2*F, a device being further provided for actively stabilizing the length of the cavity and its resonance modes so that the cavity is stably operated in a degenerated condition.