Electrooptic Femtosecond Pulse Generation using a Dispersive Optical Fiber

Femtosecond optical pulses are generated electrically from a CW narrow-linewidth laser by the electrooptic chirping-compression method. In the experiments, an electrooptic modulator is fabricated employing quasi-velocity matching by the domain inversion method to yield effectively high optical chirping rates. The sideband spectra of 1.4 THz (FWHM) are produced successfully for single pass operation of the modulator and the phase-modulated light is compressed temporally to an optical pulse train using a 50 m single-mode optical fiber with positive group delay dispersion. As a result, shortest pulses of 660 fs with 16.25 GHz repetition rate are obtained at the modulation index of Δθ=31 rad.