Flat visible spectrum by a genetic algorithm optimized photonic crystal fiber in the GHz comb spacing
Ruoao Yang, Yifan Ma, Minghe Zhao, Wei Han, Qian Li, Zhangyuan Chen, Aimin Wang, Sze Yun Set, Shinji Yamashita, Zhigang Zhang
Abstract
Coherent and flat supercontinuum (SC) sources are demanded for applications of metrology, spectroscopy, and bio-imaging. However, the process of SC generation is usually very complicated. We demonstrated a convenient and efficient method based on a genetic algorithm (GA). According to an objective spectrum, this algorithm could reverse-design the geometry of a fiber or waveguide without knowing the specific non-linear processes involved. Using this method, we designed a dispersion-managed photonic crystal fiber (PCF) for SC generation at 1 GHz comb spacing. With an input pulse of ∼150 fs, 450 pJ at 1050 nm, a 3 dB fluctuation spectrum ranging from 510 nm to 850 nm is obtained, which is absolutely fit to the calibration of an astronomical spectrograph.