Broadband laser light sources for commercial and biomedical applications

Novel optical components enable the generation of the shortest pulses and broadest spectra from Kerr-Lens mode-locked laser oscillators without extracavity spectral broadening, namely 20-fs-pulses from Cr4+:YAG around 1.5μm, 14-fs-pulses from Cr:forsterite around 1.3μm, 5-fs-pulses from Ti:sapphire around 0.8μm, and 10-fs-Pulses from Cr3+:LiCAF around 0.8μm. Key components are well adapted phase correcting mirrors ("double-chirped mirrors") which allow for high reflectivity and dispersion compensation in bandwidths up to one octave. In parallel to the development of new broadband light sources based on femtosecond technology micron resolution imaging with Optical Coherence Tomography using theses sources has been achieved. The availability of the high resolution OCT technology for future clinical applications will depend on the development of low cost, compact sources of ultrabroad bandwidth light. Especially Cr3+:LiCAF is a very promising material for femtosecond laser sources as compact replacements for Ti:sapphire oscillators because of its low quantum defect, a broadband emission range around 800 nm, and an absorption band in a spectral range where high-brightness laser diodes are available.

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