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Proceedings Paper

Delivery of ultrashort spatially focused pulses through a multimode fiber for two photon endoscopic imaging
Author(s): Edgar E. Morales-Delgado; Ioannis N. Papadopoulos; Salma Farahi; Demetri Psaltis; Christophe Moser
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Paper Abstract

Due to their high number of supported modes, multimode optical fibers carry large amount of spatio-temporal information. However, propagation of a light pulse through a multimode optical fiber suffers from spatial distortions due to superposition of the various exited modes and from time broadening due to modal dispersion. Here, we present a method based on digital phase conjugation to selectively excite specific optical fiber modes in a multimode fiber that follow similar optical paths as they travel through the fiber. In this way, they can be made to interfere constructively at the fiber output to generate an ultrashort spatially focused pulse. The excitation of a limited number of modes limits modal dispersion, allowing the transmission of an ultrashort pulse. We also show that the short spatially focused pulse can be scanned digitally without movable elements. We experimentally demonstrate that the pulse at the output of the multimode fiber generate a two-photon signal. We show delivery of a 1550 nm pulse with 500 fs duration, spatially focused to a spot size of 7 micrometers, through a 30 cm long, 200 micrometers core multimode step-index fiber. We show how this technique is applied to endoscopic two-photon imaging.

Paper Details

Date Published: 11 June 2015
PDF: 6 pages
Proc. SPIE 9531, Biophotonics South America, 95310A (11 June 2015); doi: 10.1117/12.2180332
Show Author Affiliations
Edgar E. Morales-Delgado, École Polytechnique Fédérale de Lausanne (Switzerland)
Ioannis N. Papadopoulos, École Polytechnique Fédérale de Lausanne (Switzerland)
Salma Farahi, École Polytechnique Fédérale de Lausanne (Switzerland)
Demetri Psaltis, École Polytechnique Fédérale de Lausanne (Switzerland)
Christophe Moser, École Polytechnique Fédérale de Lausanne (Switzerland)


Published in SPIE Proceedings Vol. 9531:
Biophotonics South America
Cristina Kurachi; Katarina Svanberg; Bruce J. Tromberg; Vanderlei Salvador Bagnato, Editor(s)

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