1 / 46

Status of 100 W Rod System at LZH

Status of 100 W Rod System at LZH. Ralf Wilhelm. Martina Brendel, Carsten Fallnich, Maik Frede, René Gau, Herbert Welling, Ivo Zawischa. Laserzentrum Hannover e. V. Hollerithallee 8 D-30419 Hannover Germany. Modeling. Overview Results. Experimental results. Integrated Diode Units

celine
Download Presentation

Status of 100 W Rod System at LZH

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Status of 100 W Rod System at LZH Ralf Wilhelm Martina Brendel, Carsten Fallnich, Maik Frede, René Gau, Herbert Welling, Ivo Zawischa Laserzentrum Hannover e. V. Hollerithallee 8 D-30419 Hannover Germany

  2. Modeling Overview Results Experimental results Integrated Diode Units Pump Optics Pre-Experiments Outline Resumé/Outlook

  3. pump light distribution • ray tracing • analytical approximation • experimental data Finite Element Method for calculating • temperature distribution • mechanical stress • deformation heat generation gain cooling wave propagation through inhomogenous medium • finite differencing • split step fourier approach calculation of optical properties • thermal lens • stress-induced birefringence k-vector Modeling/Overview

  4. HR 808 coating for double pass reduce thermal gradient in z-direction 100 W Laser Head end-pumped rods

  5. undoped end caps thermal lensing consists of two parts thermal part via reduced by undoped endcaps end effect (bulging of end surface) 100 W Laser Head end-pumped rods

  6. 90° quartz rotator 90° quartz rotator compensates for birefringence 100 W Laser Head end-pumped rods undoped endcaps reduce absolute temperature and thermal lens

  7. Model assumption: cylinder symmetrical pump light distribution

  8. Model assumption: cylinder symmetrical pump light distribution model takes into account wavelength/temperature dependent properties wavelength dependent absorption coefficient

  9. Model assumption: cylinder symmetrical pump light distribution model takes into account wavelength/temperature dependent properties wavelength dependent absorption coefficient temperature dependent heat conducitvity

  10. Model assumption: cylinder symmetrical pump light distribution model takes into account wavelength/temperature dependent properties wavelength dependent absorption coefficient temperature dependent heat conducitvity temperature dependent expansion coefficient

  11. Model assumption: cylinder symmetrical pump light distribution model takes into account wavelength/temperature dependent properties wavelength dependent absorption coefficient temperature dependent heat conducitvity temperature dependent dn/dT temperature dependent expansion coefficient

  12. Model assumption: cylinder symmetrical pump light distribution model takes into account wavelength/temperature dependent properties wavelength dependent absorption coefficient temperature dependent heat conducitvity temperature dependent expansion coefficient temperature dependent dn/dT

  13. 20.1°C 83.7°C Thermal Modeling/Temperature Distribution solution of time independent heat conduction equation by FEM (ANSYS) 1/4 of rod for symmetry reasons

  14. 0.0 MPa 41.3 MPa Mechanical Stress/Von Mises Equivalent Stress fracture limit for YAG 130 thru 260 MPa

  15. Thermal Lens/Abberations

  16. initial distributed E(x,y,z0) (e. g. noise) medium free propagation mirror/aperture free propagation medium free Propagation output power beam quality mirror/aperture free Propagation no yes convergence ? Fox/Li Approach Iterative Solution of Kirchhoff integral equations • inhomogenous distributed gain, refractive index, birefringence concentrated in gain/phase sheets • propagation between gain/phase sheets and in free space described by FFT propagator

  17. First Results mode diameter in rod 1 mm

  18. 100 W 120 W polarisation eigenstates First Results

  19. First Results/Birefringence Compensation

  20. First Results/100 W Head

  21. First Results/100 W Head w/o Abberations

  22. <10 nm Abberations/End Pumped vs. Transversally Pumped

  23. Pump Concepts mode selective pumping w = 1mm

  24. Pump Concepts mode selective pumping w = 2 mm

  25. Homogenization of Pump Light simulation 10 x 800 µm measured 30 x 800 µm

  26. Thermal Modeling/Temperature Distribution varying with pump spot diameter (pump power kept constant) 5000 m

  27. Thermal Modeling/Temperature Distribution varying with pump spot diameter (pump power kept constant) 2000 m

  28. Thermal Modeling/Temperature Distribution varying with pump spot diameter (pump power kept constant) 1500 m

  29. Thermal Modeling/Temperature Distribution varying with pump spot diameter (pump power kept constant) 1000 m

  30. Thermal Modeling/Temperature Distribution varying with pump spot diameter (pump power kept constant) 750 m

  31. Thermal Modeling/Temperature Distribution varying with pump spot diameter (pump power kept constant) 500 m

  32. Thermal Modeling/Maximum Temperature

  33. Von Mises Stress varying with pump spot diameter (pump power kept constant) 5000 m

  34. Von Mises Stress varying with pump spot diameter (pump power kept constant) 2000 m

  35. Von Mises Stress varying with pump spot diameter (pump power kept constant) 1500 m

  36. Von Mises Stress varying with pump spot diameter (pump power kept constant) 1000 m

  37. Von Mises Stress varying with pump spot diameter (pump power kept constant) 750 m

  38. Von Mises Stress varying with pump spot diameter (pump power kept constant) 500 m

  39. Mechanical Stress/Von Mises Equivalent Stress varying with pump spot diameter (pump power kept constant)

  40. Experimental/Diode Temperature Control laser diode JENOPTIK 30 W, fiber coupled, NA 0.22; 800 m temperature resolution: 0.01K temperature fluctuations: 2-3 digits temperature stability better than 0.05K

  41. 4 boxes • each 10 X 30 W fiber-coupled diodes  1200 W pump Power Experimental/Diode Box user interface 4 systems (boxes) 40 temperatures laser diode (10) heat sink (2) 4 current controls (1 per box) ADC/DAC upcoming: • 40 diode power measurements  laser power control for each diode overtemp interlocks peltier drivers

  42. 2.5 cm Pump Chamber water flow

  43. Pre-experiments laser rod pump optic TR multimode M2 < 3

  44. Birefringence Compensated Resonator Faraday Rotator thermal lens image Faraday Rotator laser rod pump optic TR

  45. Resumé Modeling • 100 W of output power will be achieveable • abberations will have to be compensated for • abberations are comparable in end pumped and transversally pumped rod Experimental • 4 diode boxes have been set up (1200 W of pump power) • temperature stabilization works • pump light homogenization has been demonstrated • 45 W single mode and 75 W multi mode laser has been demonstrated (single rod, no compensation)

  46. Outlook • optimize overlap of pump light distribution and mode diameter • compare calculated abberations to experiment (Shack-Hartmann sensor, diploma thesis P. Huke) • evaluate conductive cooling (coating of rod‘s shell) -reduce abberations (lower absolute temperature) -avoid contact of cooling fluid with rod • compensate for abberations doped region ? pump

More Related