Optimizing pulse compressibility in completely all-fibered Ytterbium chirped pulse amplifiers for in vivo two photon laser scanning microscopy

• Published in: Biomedical optics express Vol. 8; no. 8; pp. 3526 - 3537
• Main Authors: Fernández, A, Grüner-Nielsen, L, Andreana, M, Stadler, M, Kirchberger, S, Sturtzel, C, Distel, M, Zhu, L, Kautek, W, Leitgeb, R, Baltuska, A, Jespersen, K, Verhoef, A
• Format: Journal Article
• Language: English
• Published: United States Optical Society of America 01.08.2017
• Subjects: (180.5810) Scanning microscopy; (320.7090) Ultrafast lasers; (060.2320) Fiber optics amplifiers and oscillators; (180.4315) Nonlinear microscopy
• ISSN: 2156-7085; 2156-7085
• DOI: 10.1364/boe.8.003526

A simple and completely all-fiber Yb chirped pulse amplifier that uses a dispersion matched fiber stretcher and a spliced-on hollow core photonic bandgap fiber compressor is applied in nonlinear optical microscopy. This stretching-compression approach improves compressibility and helps to maximize the fluorescence signal in two-photon laser scanning microscopy as compared with approaches that use standard single mode fibers as stretcher. We also show that in femtosecond all-fiber systems, compensation of higher order dispersion terms is relevant even for pulses with relatively narrow bandwidths for applications relying on nonlinear optical effects. The completely all-fiber system was applied to image green fluorescent beads, a stained lily-of-the-valley root and rat-tail tendon. We also demonstrated imaging in zebrafish larvae, where we simultaneously measure second harmonic and fluorescence from two-photon excited red-fluorescent protein. Since the pulses are compressed in a fiber, this source is especially suited for upgrading existing laser scanning (confocal) microscopes with multiphoton imaging capabilities in space restricted settings or for incorporation in endoscope-based microscopy.