PCF infrared continuum for multiwavelength two photon microscopy

Thanks to the non linearity arising when femtosecond pulses are coupled into Photonic Crystal Fibers (PCFs), continuum spectra can be generated starting from single wavelength lasers. Multiphoton microscopy, fluorescence lifetime imaging, stimulated emission depletion microscopy, and optical coherence tomography have been previously realized using such kind of excitation source, covering most of the state of-the-art biological imaging techniques. Usually the properties of PCFs in terms of anomalous dispersion and high non linearity are exploited to produce the greater spectral broadening. We choose instead to pump a PCF with a selected dispersion profile in the normal dispersion region. This approach results in effects: reduction of non linearity, flat spectrum at the output and reduced amplitude noise in the different spectral bands generated.