Broadband supercontinuum generation with low peak power in controllable C 7 H 8 -core photonic crystal fibers of characteristic quantities

In this paper, we propose a newly designed toluene-core (C 7 H 8 -core) photonic crystal fiber (PCF) with a hexagonal lattice. The difference in the diameter of the air holes in the first ring and the other rings improves the nonlinear properties of the fiber. By varying the filling factor d 1 / Λ ( d 1 is the air-hole diameter of the first lattice ring near the core) and lattice constant Λ of the PCF in the wavelength range of 0.5 μm to 2 μm, parameters such as dispersion and effective mode area could be optimized. The advantages of these PCFs are flat near-zero dispersion, small effective mode area, and high nonlinear coefficients. To analyze the nonlinear properties and supercontinuum generation, we selected two optimal structures from the simulation results. The optimal PCF only needs to deliver power at low peak power, but still achieves the best-broadened spectrum compared to previous works. The first fiber #F 1 with a lattice constant ( Λ = 1.0 µm) and filling factor ( d 1 / Λ = 0.5) has all-normal dispersion and provides a supercontinuum (SC) spectrum in the range of 0.72 µm to 1.78 µm. It has a pump wavelength of 1.3 μm, a pulse width of 40 fs, and a peak power of 0.45 kW. The fiber #F 2 enables supercontinuum generation in the anomalous dispersion regime with a pump wavelength of 1.5 μm and pulse width of 80 fs. The spectral width of fiber #F 2 obtained with a peak power of 75 kW is 3.46 μm. The two proposed fibers have the potential to become new fiber types for all-fiber SC sources, as alternatives to glass-core fibers for next-generation broadband sources.