Seminarium Optyczne

Currently available fiber gain media limit the operation of high-performing fiber lasers mainly to the spectral regions around 1.0 μm, 1.55 μm or 1.9 μm. Fiber light sources providing wavelength tunability outside these spectral regions are less common although highly demanded for applications, for instance, in nonlinear spectroscopy and microscopy. The current technological solutions exploit nonlinear effects of frequency conversion in optical fibers, such as soliton self-frequency shift, soliton self-mode conversion recently observed in multimode fibers, Four-Wave-Mixing (FWM), supercontinuum generation (SCG) combined with narrowband filtering, and self-phase-modulation (SPM). Here, we will discuss new ideas for developing multicolor light sources that have been further implemented in CARS microscope. In particular, we will show how the concatenation of standard and photonic crystal fibers permits to tune FWM sidebands by varying the chirp of the input pump pulse and keeping the pump central wavelength fixed. We will also demonstrate how by using a few-mode fiber or a highly multimode fiber, it is possible to build a self-referenced CARS microscope that does not require an external pump beam combined with a delay-line system.