Optimization of optical properties of toluene-core photonic crystal fibers with circle lattice for supercontinuum generation

We emphasize the advantage of varying the filling factor d1/Λ in the first cladding ring of toluene-core PCFs with circle lattice in enhancing the fiber nonlinearity. The guiding characteristic of the fiber such as the dispersion, nonlinear coefficients, and attenuation of the fundamental mode is studied numerically. Based on the simulation results, two optimal PCFs are selected and investigated in detail for the spectrally broad supercontinuum (SC) generation with low input energy. The first PCF with a lattice constant (Λ) of 1.0 μm and filling factor (d1/Λ) of 0.7 has the all-normal dispersion in the wavelength range of 0.7–2.0 µm. When the 1-cm-long fiber samples are pumped at 1.064 μm, the generated SC spectra span from the visible to near-infrared regions (0.642–1.592 μm), with the low pulse energy of 0.018 nJ. Meanwhile, the second PCF (Λ = 2.5 μm, d1/Λ = 0.3) allows for SC in the anomalous dispersion regime in the range 0.911–2.496 µm with pulse energy of 0.05 nJ when the pulse has a central wavelength of 1.55 µm propagating within 10 cm of the fiber samples. The proposed design could be a new class of microstructure optical fiber for the broad spectrum SC generation.