Noise reduction of high-power supercontinuum sources by back seeding

Abstract

Ultra-broadband high-power supercontinuum (SC) light sources are currently being applied to a wide range of biooptical applications, in which noise is a severely limiting factor. With picosecond pumping, as we consider here, noise is inherent in the SC generation process, because the generation is initiated by modulation instability (MI), which amplifies random fluctuations in the pump pulse. Above a certain threshold power the original pulse breaks up into a train of solitons, which evolves into a supercontinuum [1]. Recently it has been shown that by seeding the four-wave mixing (FWM) gain wavelengths, SC generation close to the threshold can be accelerated and the noise can be greatly reduced [2,3]. The noise is reduced because the seed initiates the MI in a controlled manner, thereby removing a great deal of the randomness in the SC generation process [3]. The theory behind it builds on the recent discovery of Rogue waves in SC [4,5].