Spectrally-bounded continuous-wave supercontinuum generation in a fiber with two zero-dispersion wavelengths

A common issue in fiber-based supercontinuum (SC) generation under continuous-wave pumping is that the spectral width of the resulting source is related to the input power of the pump laser used. An increase of the input pump power leads to an increase of the spectral width obtained at the fiber output, and therefore, the average power spectral density (APSD) over the SC spectrum does not grow according to the input power. For some applications it would be desired to have a fixed spectral width in the SC and to increase the average PSD proportionally to the input pump power. In this paper we demonstrate experimentally that SC generation under continuous-wave (CW) pumping can be spectrally bounded by using a fiber with two zero-dispersion wavelengths (ZDWs). Beyond a certain pump power, the spectral width of the SC source remains fixed, and the APSD of the SC grows with the pump power. In our experiment we generate a reasonably flat, spectrally-bounded SC spanning from 1550 nm to 1700 nm. The spectral width of the source is shown to be constant between 3 and 6 W of pump power. Over this range, the increase in input power is directly translated in an increase in the output APSD. The experimental results are confirmed by numerical simulations, which also highlight the sensitivity of this configuration to variations in the fiber dispersion curve. We believe that these results open the way for tailoring the spectral width of high-APSD CW SC by adjusting the fiber dispersion. (C) 2008 Optical Society of America.