STh3L.3.pdf
CLEO:2015 © OSA 2015
Dissipative soliton thulium fiber laser with pulse energy above 10 nJ Yuxing Tang* and Frank W. Wise School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, USA *Corresponding author:
[email protected]
Abstract: Dissipative-soliton operation of a Tm fiber laser yields 11 nJ pulses, which is several times the energy of prior femtosecond Tm fiber lasers. The pulses can be dechirped to 200 fs duration. © 2014 Optical Society of America OCIS codes: (140.4050) Mode-locked lasers; (320.5550) Pulses
1.
Introduction
Since their initial experimental realization by Chong et al. in 2006 [1], dissipative soliton fiber lasers have shown great potential for competing with solid-state lasers. A chirped pulse in the cavity can be stable with high energy, tolerate large nonlinear phase shifts without wave breaking, and can be externally compressed to transform limit. Recently, Tm-doped fiber lasers have attracted great attention for wide-ranging applications, including atmospheric gas detection, lidar and medical treatments. As a gain medium, Tm-doped fibers provide a broad gain bandwidth and high quantum efficiency. Dissipative soliton lasers incorporating Tm-doped gain fiber serve as a promising option for high energy, ultrashort pulses at 2 µ m. Tm lasers which exhibited characteristic steep-sided, ’batman ear’ spectra have been demonstrated [2] [3], however the pulse energy was limited to 2.2 nJ, which is well below the maximum energy expected. In this paper, we report a dissipative soliton Tm fiber laser with single pulse energy of 11 nJ, demonstrating a 5-fold improvement in pulse energy without wave breaking. Future directions will be discussed.
Fig. 1. schematic of Tm laser cavity.
2.
Experiment
The primary limitation to obtaining high energy pulses at 2 µ m is likely the anomalous GVD which is typical in Tmdoped silica gain fibers. In order to operate in the net normal dispersion regime, dispersion compensation is required. We employed a high NA fiber for dispersion compensation. Simulations guided the exact choice of fiber lengths and other parameters. The laser setup is shown in Fig. 1 with net cavity dispersion of 0.3 ps2 . Pump power of 1 W is provided by our home-built Er laser and a 20 nm bandwidth filter is used.
STh3L.3.pdf
CLEO:2015 © OSA 2015
Single pulse energy of 11 nJ at repetition rate of 21.5 MHz with chirped pulse duration of 3.6 ps is obtained (Fig. 2). Single pulsing is confirmed with long scan range (150 ps) autocorrelation and fast detector with resolution of 30 ps. Using a grating pair compressor, the pulse can be dechirped to 205 fs, near the transform limit of 200 fs. The steady state evolution is relatively static (experimental and simulation results indicate spectral and temporal breathing below 2 and 3 respectively). Along with the characteristics of the spectrum and pulse, this suggests the laser produces dissipative soliton pulses. Even higher pulse energy and shorter duration are anticipated in simulation and optimization of filter and cavity dispersion will be our future work.
Fig. 2. Experimental output: (a) mode-locked spectrum; (b) interferometric autocorrelation of dechirped pulse (black) and transform limit pulse (red); (c) autocorrelation of chirped pulse.
3.
Conclusion
In summary, a dissipative soliton Tm fiber laser with single pulse energy over 10 nJ is reported. The combination of the dissipative soliton evolution and the Tm gain medium should enable high-performance, practical light sources for a range of mid-IR applications. 4.
Acknowledgements
This work was supported by National Science Foundation under grant ECCS-1306035. References 1. A. Chong, J. Buckley, W. Renninger, and F. Wise, “All-normal-dispersion femtosecond fiber laser,” 14, 660–662 (2006). 2. F. Haxsen, D. Wandt, U. Morgner, J. Neumann, and D. Kracht, “Monotonically chirped pulse evolution in an ultrashort pulse thulium-doped fiber laser.” Optics letters 37, 1014–6 (2012). 3. R. Gumenyuk, I. Vartiainen, H. Tuovinen, and O. G. Okhotnikov, “Dissipative dispersion-managed soliton 2 µ m thulium/holmium fiber laser.” Optics letters 36, 609–611 (2011).
