Super-continuum generation, four-wave mixing (FWM), and hollow-core Photonic crystal fibers (PCF) are technologies that have the potential to enable breakthroughs in medicine and microscopy. Scientists have endeavored to tailor supercontinua and related sources to match demanding applications requiring higher spectral power density, power focused in a particular spectral region or longer or shorter wavelengths. PCF can provide the necessary normal dispersion at Yb 3+ doped fiber laser wavelengths. This continuum has reduced spectral coverage, but its amplitude noise is decreased to the level of the pump laser. HC PCFs are created with a built-in high-NA annular return path for the signal light and multicore HC PCFs for multiple point sampling by using the design and fabrication flexibility of PCF.