Share Email Print
cover

Proceedings Paper • new

Observation of transverse-mode instabilities in a thulium-doped fiber amplifier
Author(s): Christian Gaida; Martin Gebhardt; Tobias Heuermann; Ziyao Wang; Fabian Stutzki; Cesar Jauregui; Jens Limpert
Format Member Price Non-Member Price
PDF $14.40 $18.00
cover GOOD NEWS! Your organization subscribes to the SPIE Digital Library. You may be able to download this paper for free. Check Access

Paper Abstract

We analyze the average power scaling capabilities of ultrafast thulium-doped fiber lasers in the context of available pump brightness and transverse-mode instabilities. It has been theoretically predicted that thulium-doped fiber lasers emitting at around a wavelength of 2 μm can withstand much higher thermal loads before the onset of mode instability is observed. In this work we intend to verify this theoretical hypothesis experimentally. To do so, we use state of the art laser diodes to reach a combined pump power of more than 2 kW at 793 nm. Careful thermal management of the fiber amplifier and sufficient seed power are beneficial for exploiting cross-relaxation, which allows for high optical to optical efficiencies greater than 50%, which we demonstrate in a 50/250 thulium-doped photonic crystal fiber. An average power of 1060 W after pulse compression to 265 fs duration with stable diffraction-limited beam quality is demonstrated. We have achieved a pump-limited average output power of 1.15 kW prior to pulse compression without the onset of thermal mode instability. After a longer period of operation at this power level, a degradation of the amplifier performance occurred and thermal mode instability has been observed for average powers in excess of 847 W. This is the first time, to the best of our knowledge, that thermal mode instability has been observed in a thulium-doped fiber laser. According to simulations of the amplification process, the average heat load at the threshold of thermal mode instability is at least 95 W/m, which is about 3 times higher than the typical value for ytterbium-doped fiber laser.

Paper Details

Date Published: 7 March 2019
PDF: 6 pages
Proc. SPIE 10897, Fiber Lasers XVI: Technology and Systems, 1089702 (7 March 2019); doi: 10.1117/12.2509714
Show Author Affiliations
Christian Gaida, Friedrich-Schiller-Univ. Jena (Germany)
Martin Gebhardt, Friedrich-Schiller-Univ. Jena (Germany)
Helmholtz Institute Jena (Germany)
Tobias Heuermann, Friedrich-Schiller-Univ. Jena (Germany)
Helmholtz Institute Jena (Germany)
Ziyao Wang, Friedrich-Schiller-Univ. Jena (Germany)
Fabian Stutzki, Friedrich-Schiller-Univ. Jena (Germany)
Fraunhofer-Institut für Angewandte Optik und Feinmechanik (Germany)
Cesar Jauregui, Friedrich-Schiller-Univ. Jena (Germany)
Jens Limpert, Friedrich-Schiller-Univ. Jena (Germany)
Helmholtz Institute Jena (Germany)
Fraunhofer-Institut für Angewandte Optik und Feinmechanik (Germany)


Published in SPIE Proceedings Vol. 10897:
Fiber Lasers XVI: Technology and Systems
Adrian L. Carter; Liang Dong, Editor(s)

© SPIE. Terms of Use
Back to Top