High-average-power actively-mode-locked Tm3+ fiber lasers

Fiber lasers emitting in the 2 μm wavelength range doped with thulium ions can be used as highly efficient pump sources for nonlinear converters to generate mid-infrared radiation. For spectroscopic purposes, illumination and countermeasures, a broad mid-infrared emission spectrum is advantageous. This can be reached by supercontinuum generation in fibers, e.g. fluoride fibers, which up to now has, however, only been presented with either low average power, complex Raman-shifted 1.55 μm pump sources or multi-stage amplifier pump schemes. Here we present recent results of a new actively-mode-locked single-oscillator scheme that can provide the high-repetition rate sub-ns pump pulses needed for pumping supercontinuum generators. A thulium-doped silica fiber laser is presented that provides > 11 W of average power CW-mode-locked pulses at 38 MHz repetition rate at ~ 38 ps pulse width. Upgrading the setup to allow Q-switched mode-locked operation yields mode-locked 40 MHz pulses arranged in 60 kHz bunched Q-switch envelopes and thus increases further the available peak power. In this Q-switched mode-locked regime over 5 W of average power has been achieved.

[1]  J. Walewski,et al.  Generation of a continuum extending to the midinfrared by pumping ZBLAN fiber with an ultrafast 1550-nm source , 2006, IEEE Photonics Technology Letters.

[2]  T. A. King,et al.  Self-induced pulsations, Q-switching and mode-locking in Tm–silica fibre lasers , 2005 .

[3]  Mohammed N. Islam,et al.  W Time-Averaged Power MidIR Supercontinuum Generation Extending Beyond 4 μ m With Direct Pulse Pattern Modulation , 2009 .

[4]  Almantas Galvanauskas,et al.  Power scalable mid-infrared supercontinuum generation in ZBLAN fluoride fibers with up to 1.3 watts time-averaged power. , 2007, Optics express.

[5]  Evgueni M. Dianov,et al.  Mode-locked 1.93 μm thulium fiber laser with a carbon nanotube absorber , 2008 .

[6]  Dietmar Kracht,et al.  Pulse characteristics of a passively mode-locked thulium fiber laser with positive and negative cavity dispersion. , 2010, Optics express.

[7]  Mohammed N. Islam,et al.  Supercontinuum generation from ~1.9 to 4.5 μmin ZBLAN fiber with high average power generation beyond 3.8 μm using a thulium-doped fiber amplifier , 2011 .

[8]  Stuart D. Jackson,et al.  Comparative study of continuous wave Tm3+-doped silica and fluoride fiber lasers , 2008 .

[9]  M.N. Islam,et al.  10.5 W Time-Averaged Power Mid-IR Supercontinuum Generation Extending Beyond 4 $\mu$m With Direct Pulse Pattern Modulation , 2009, IEEE Journal of Selected Topics in Quantum Electronics.

[10]  Terence A. King,et al.  Dynamics and self-pulsing effects in Tm3+-doped silica fibre lasers , 2002 .

[11]  Christelle Kieleck,et al.  High-power actively mode-locked sub-nanosecond Tm³⁺-doped silica fiber laser. , 2011, Optics letters.

[12]  Gwenael Mazé,et al.  Mid-infrared supercontinuum generation to 4.5 microm in ZBLAN fluoride fibers by nanosecond diode pumping. , 2006, Optics letters.