The Physics of Ultrabroadband Frequency Comb Generation and Optimized Combs for Measurements in Fundamental Physics
Technical Report,01 Feb 2013,31 Jan 2016
Universite De Besancon Besancon France
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This project had as its aim to carry out targeted numerical and experimental studies into the properties of optical frequency comb sources. The generation of frequency combs is intimately connected with the nonlinear spectral broadening that occurs in optical fibers due to the Kerr effect, and our initial work focussed on fundamental studies examining the sensitivity of such nonlinear spectral broadening to input noise, and the development of techniques to reduce such noise with the presence of an external seed source. To perform fundamental studies of this process, we considered the case of spontaneous four wave mixing or modulation instability, which is the noise-driven analogue of the process generating frequency combs. Our experimental set-up is shown below and illustrates how the nonlinear spectral broadening induced by the 20 MHz pump laser source in 9.5 m of highly nonlinear fiber HNLF was combined with a seeding source whose aim was to lower the threshold for spectral broadening by stimulating it from either a narrowband 100 kHz linewidth continuous wave or a partially coherent seed.