High power VBG Yb-fiber laser Slope eff. ~75 % Δλ = 0.4 nm M2~5.5 Yb-fiber Core:  30 m, NA 0.056 D-shaped cladding :  400 m, NA 0.49 Fiber length : ~8 m (abs. ~2 dB/m at 975 nm) Launch efficiency : ~90 % VBG 1.5mm 3mm 5mm Δλ = 0.22 nm, λcentre = 1066.0 nm, R= 99 % AR coated surface normal polished ~2o to the grating vector P. Jelger, P. Wang, J. K. Sahu, F. Laurell, and W. A. Clarkson, Opt. Expr. 16, 9507 (2008)

Transversally chirped VBG Yb laser > 100 W output > 78 % slope efficiency Tunable from 1064-1073 nm <0.5 % power fluctuation over tuning range Narrowband signal < 50 pm Temporal stability <0.2 % rms M2 = 1.2 Single-polarization >18 dB PER Tcvbg – design wavelength of the grating is chirped such that lateral translation will tune the laser wavelength Low core NA --> easy to operate the fiber in a single mode  since higher order modes are strongly suppressed by coiling  particularly important for self-pulsing suppression Expected perfomance: calculate the laser power at maximum launched pump power using a spectrally resolved rate equation model Using available yb absorption and emission cross sections… Take a look at the scale of the color bar on the right hand side… 1st Obviously  high gain laser medium 2nd due to the rather constant emission cross section of Yb in that region… SBS threshold approx. 5 kW

Tunable, high-power, 2 wavelength Yb laser Dual-line lasing 78 W wavelength separation 0.03 - 2 THz, Power fluctuation<1 %. Results for the SHG generation

Kerr-Lens ML Ti:sapphire laser Ultra-fast lasers Kerr-Lens ML Ti:sapphire laser D.E. Spence, P.K. Kean, and W. Sibbet Opt. Lett. 16, 42 (1991) M. Piché, Opt. Commun. 86, 156 (1991) Patent for the Aperture (Coherent)

The Frequency Comb T  = phase offset between carrier wave and wave envelope fm = mfrep + foffset frep= 1/T foffset = ( /2) frep Therefore if  = 0  foffset= 0  fm = mfrep The idea has revolutionized the art of frequency measurements Theodor W. Hänsch e John L. Hall, Nobel Prize for Physics (2005)

High Peak Intensities Lasers oscillator  103 - 105 stretcher up to 105 amplifier  10-3 – 10-5 compressor Chirped Pulse Amplification (CPA) D. Strickland and G. Mourou (1985)  Ti:Al2O3 : 1-10 mJ; f = 1-10 kHz  TTT [Terawatt Table Top] Lasers : 100 TW (5 J, 50 fs)  Petawatt-class Lasers (1,5 PW, i.e. 580 J and 460 fs)

Historical Evolution of Pulse Duration From Femtoseconds to Attoseconds 4 fs 80 as: E. Goulielmakis et. al., Science 320, 1614 (2008)

Everything...

In Science Laser cooling Na-atom molasses 6 laser beams with frequency slightly shorter than the transition frequency. Reduced the energy of a cloud of atoms to form an optical molasses. Temperatures down to micro-Kelvin. Nobel prize in 1997 for Chu, Cohen-Tannoudji and Phillips

The world's largest and highest-energy laser the National Ignition Facility at Lawrence Livermore In the NIF experiments 192 giant laser beams are focused on a cm-sized target filled with hydrogen fuel. NIF's goal is to fuse the hydrogen atoms' nuclei and produce net energy gain (Eout = 100 Ein) The beams compress the target to 100 billion times the atmosphere to a temperature of 100 million °C

Imaging and displays – large, small or 3D

References can be found on Conclusions Solid-state lasers efficient Reliable tailored fun And…. Acknowledgments Friends and laser family References can be found on www.laserphysics.kth.se

That´s all folks!

Hollow fiber dye and Q-dots sources Scematic layout Photograph of Rodamine 6G filled fiber Green pumped hollow fibre in wich dye is pumped

Functional optical materials and structures Chemically and photostructured glasses Domain engineered ferroelectrics Quantum dots Silicone elastomers Microstructured silicon

Acknowledgments Laser physics group National and international colleagues www.laserfest.org

Limitations related to thermal loading 2 mm FEM simulation Width of VBG [mm] Distance into VBG [mm] Temperature distribution 1 kW 3 mm 5 mm Absorption 0.2%/cm Δ λ ~ 0.5 nm Chirp reduces reflectivity! VBG would transmit more power! Significant problem for low gain lasers and high circulating powers

> 30 W Single Frequency CW VBG OPO P. Zeil, et al. Optics Express, 22, 29907-29913 (2014).