Fundamentals of stable continuum generation at high repetition rates

A continuum generated from highly nonlinear seed pulses (N/spl Gt/1) propagating in a medium with only self-phase modulation (SPM) or with SPM and anomalous dispersion is highly sensitive to the noise of the input pump pulse. The combination of SPM and normal dispersion improves the stability. However, more efficient spectral broadening schemes are desirable for generating a broad-band continuum at gigahertz rates. The adiabatic compression of weakly nonlinear pulses (N/spl sime/1) via the soliton effect efficiently generates a broad-band continuum that is robust against noise. Detailed characterization of continuum generation in several different fibers is reported.