All-Fiber ultraflat supercontinuum generation in photonic crystal fibers covering 492.4 − 2009.8 nm with 3-dB bandwidth

In this study, a new approach for realizing all-fiber ultraflat supercontinuum (SC) generation is proposed. The proposed method combines the efficient coupling principles between solitons and dispersive waves (DWs) with spectral filtering. After a series of calculations and simulations, the end-face structure of sample #2 is selected for photonic crystal fiber (PCF) drawing. Ultraflat SC generation is achieved by employing a 3.06 W-pumped 10-m PCF combined with long-period grating-assisted spectral filtering techniques. The 3-dB bandwidth extends to 1517.4 nm (492.4 − 2009.8 nm), spanning an optical octave of 2.02 and thus representing the largest optical octave reported for an all-fiber SC source with a 3-dB bandwidth. In this work, shorter highly nonlinear fibers and simpler pumping techniques are used compared with conventional ultraflat SC generation methods. This compact and robust configuration provides an alternative solution for multiwavelength spectroscopy, hyperspectral radar imaging , and optical clock systems .