Temporal coherence control by electro-optic phase modulation

We developed an efficient electro-optic phase modulator for deep microwave modulation to control temporal coherence of laser light. Deep modulation was achieved by quasi-velocity matching between modulation microwave and light with periodic domain inversion of a bulk electro-optic crystal. The interaction length is only limited by a diffraction loss in the bulk modulator. Sideband broadening up to 3 THz by 16.25 GHz modulation was achieved in the experiment with an Ar laser. Effective coherence time and length of the modulated light are 0.3 ps and 0.1 mm, respectively.