Supercontinuum generation in highly nonlinear fibers using amplified noise-like optical pulses

Supercontinuum generation in a highly nonlinear fiber pumped by noise-like pulses from an erbium-doped fiber ring laser is investigated. To generate ultrabroad spectra, a fiber amplifier is used to boost the power launched into the highly nonlinear fiber. After amplification, not only the average power of the noise-like pulses is enhanced but the spectrum of the pulses is also broadened due to nonlinear effects in the fiber amplifier. This leads to a reduction of the peak duration in their autocorrelation trace, suggesting a similar extent of pulse compression; by contrast, the pedestal duration increases only slightly, suggesting that the noise-like characteristic is maintained. By controlling the pump power of the fiber amplifier, the compression ratio of the noise-like pulse duration can be adjusted. Due to the pulse compression, supercontinuum generation with a broader spectrum is therefore feasible at a given average power level of the noise-like pulses launched into the highly nonlinear fiber. As a result, supercontinuum generation with an optical spectrum spanning from 1208 to 2111 nm is achieved using a 1-m nonlinear fiber pumped by amplified noise-like pulses of 15.5 MHz repetition rate at an average power of 202 mW.