Pulse separation control for mode-locked far-infrared p-Ge lasers

Active mode locking of the far-infrared p-Ge laser giving a train of 200 ps pulses is achieved via gain modulation by applying an rf electric field to gether with an additional bias at one end of the crystal parallel to the Vo igt-configured magnetic field. Harmonic mode locking yields a train of puls e pairs with variable time separation from zero to half the roundtrip perio d, where pulse separation is electrically controlled by the external bias t o the rf field. (C) 1999 American Institute of Physics. [S0003-6951(99)0200 2-1].