We have numerically studied a hollow-core photonic crystal fiber, with its core filled with highly nonlinear liquids such as carbon disulfide and nitrobenzene. Calculations show that the fiber has an extremely high nonlinear parameter gamma on the order of 2.4/W/m at 1.55 mum. The group velocity dispersion of this fiber exhibits an anomalous region in the near-infrared, and its zero-dispersion wavelength is around 1.55 mum. This leads to potentially significant improvements and a large bandwidth in supercontinuum generation. The spectral properties of the supercontinuum generation in liquid-core photonic crystal fibers are simulated by solving the generalized nonlinear Schrödinger equation. The results demonstrate that the liquid-core PCF is capable to generate dramatically broadened supercontinua in a range from 700 nm to more than 2500 nm when pumping at 1.55 mum with subpicosecond pulses.

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We investigate the group velocity dispersion of tapered fibers that are immersed in different liquids. Using the Sellmeier equations fitted from measured refractive indices of these liquids, we are able to analyze the dispersion characteristics of the tapered fibers in a tailored liquid environment. Theoretical results show a large span of slowly varying anomalous group velocity dispersion characteristics. This leads to potentially significant improvements and a large bandwidth in supercontinuum generation in a tapered fiber. This holds true as well for a range of new fiber materials.

The combination of a diode-pumped Nd:YVO4 picosecond laser source with tapered fibers allows the realization of a compact white light source with an average output power of up to 5.65 W. We generated supercontinua with a throughput of ~50% over a spectral range of up to 1140 nm by using a series of tapered fibers that were spliced together.