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BP: Fachverband Biologische Physik

BP 12: Posters: New Technologies

BP 12.4: Poster

Monday, March 14, 2011, 17:15–20:00, P3

Characterization and compensation of fs-Laser pulse broadening in a photonic crystal fiber for multi-photon endo-microscopy — •Tobias Ehmke, Sabine Donner, Alexander Krueger, and Alexander Heisterkamp — Laser Zentrum Hannover e.V., Hollerithallee 8, D-30419 Hannover

Multi-photon excitation microscopy is a fluorescence imaging technique which allows deep tissue imaging with short pulse infrared laser light. The optics of conventional multiphoton microscopes is too bulky for endo-microscopy and the rigid setup is unfavourable for many in-vivo applications. In order to gain flexibility and reduce size a fiber based probe for multiphoton endomicroscopy is under development. As a first step towards the endomicroscope problems associated with the propagation of short pulses in the optical fibers have to be addressed. Therefore, a setup consisting of a Ti:Sa laser emitting 140fs pulses, a prechirp unit, a double clad photonic crystal fiber and focussing optics are used. The dispersion and nonlinear effects in the fiber are studied with an autocorrelator and a spectrometer. The coupling efficiency of the fiber is determined to be over 60%. Without the prechirp unit pulse broadening into the ps-regime and a reduction of the spectral width is observed. The dispersion could be compensated by a grating compressor, generating a negative chirp for the pulse and is designed to put the pulse length back into the fs-regime behind the fiber. This is an important step towards the utilization of a fiber based multi-photon microscope for in-vivo applications.