An all-solid-state sub-40-fs self-starting Cr4+: Forsterite laser with holey-fiber beam delivery and chirp control for coherence-domain and nonlinear-optical biomedical applications

An all solid-state sub-40-fs self-starting Cr4+: forsterite laser with a wa velength tunable within the range of 1.21-1.29 mum adapted in its power, te mporal, and spectral parameters for high-resolution optical coherence tomog raphy (OCT) and nonlinear-optical tissue imaging is presented. Stable self- starting mode locking in the created laser is achieved both with and withou t semiconductor saturable-absorber mirrors, while the double-pulse regime o f lasing permits time-resolved measurements on biological systems to he per formed. Frequency doubling is implemented through second-harmonic generatio n in a 2.5-mm-long DCDA crystal, ensuring group-velocity matching for femto second pulses produced by the Cr: forsterite laser. A set of holey fibers w ith a period of the photonic-crystal structure of the cladding ranging from 468 nm to 32 mum ensure the tunability of the photonic band gap of the cla dding within a broad spectral range, providing different waveguiding regime s for Cr4+: forsterite laser radiation.