Nonlinear Generation of Ultra-Flat Broadened Spectrum Based on Adaptive Pulse Shaping

This paper investigates the nonlinear generation of ultra-flat broadband spectra suited to communication applications. The technique is based on the inclusion of a linear pulse shaping element prior to a nonlinear fiber, where highly controllable spectral broadening is enabled. An adaptive pulse shaping system exploiting optimization algorithms (evolution strategy-ES) allows for automatic convergence to the desired spectrum. Using this technique, a spectrum exhibiting a 3-dB bandwidth of ~12 nm and a 0.5-dB bandwidth of ~8 nm is reported. The technique can be used to generate even broader spectra or indeed spectra exhibiting more exotic shapes.