Optimization of pump wavelength for enhancing SC spectralbroadening in silica fibers under CW-excitation

摘要

Supercontinuum sources generated by continuous-wave excitation are very promising for many applications as theypresent in general higher spectral power density then their pulsed counterparts. On the other hand, the properties ofsupercontinuum are very difficult to be controlled as the initial broadening is driven by modulation instability. This latterone breaks-up the CW radiation into a train of ultra-short pulses whose peak power, spectral length and shape stronglydepend on the power, coherence and noise of the pump and on the fiber properties. In this paper, we present apreliminary work on the role of chromatic dispersion on supercontinuum spectral broadening in order to study how tooptimize SC spectral width under CW regimes. By means of a home-made tunable high-power laser we inducesupercontinuum generation by pumping at different dispersion values of the fiber. We show that at low injected powersthe wider spectrum is obtained when pumping just above the zero-dispersion wavelength of the fiber. By contrast, forhigher injected powers, wide and squared-shaped spectra can be obtained when pumping over a larger range ofanomalous dispersion values. These results seem to be very promising for a number of applications requiring smooth,squared and high-power SC spectral profiles such as optical coherence tomography.