Mid-IR quantum cascade laser mode coupling in hollow-core, fiberoptic waveguides with single-mode beam delivery

摘要

We report a theoretical and experimental study of laser coupling in hollow-core, fiber-optic waveguides with small-bore diameters of d=200 μm. For the experiments we utilized three mid-infrared quantum cascade lasers with different emission wavelength, which were coupled into the waveguides using lenses with focal lengths in the range 25-76 mm. Measurements of the output beam profiles and propagation losses were obtained as a function of the coupling conditions. With appropriate coupling parameters, single mode beam delivery can be obtained for all laser wavelengths, ranging from λ ～ 5.4 to 10.5 μm.