Generation of sub-picosecond optical pulses at 0.3-THz repetition rate by induced modulational instability.

We report the generation of 0.5-psec FWHM optical pulses at 0.3-THz (tunable) repetition rate via an induced modulational instability in a single-mode fiber. A 1.319micron Nd:YAG laser is chosen as the carrier wave and the initial modulation on this carrier in introduced by mixing it with an external- grating-cavity InGAsP laser. The use of this all-optical modulating scheme and the nonlinear optical propagation effect in fiber (i.e., modulational instability) allows one to reach into the terahertz regime, which is about two orders of magnitude beyond the fastest data limited by the finite response of electronics.