Tunable Cr:F Femtosecond Lasers

1. Tunable Cr:F Femtosecond Lasers Research and Industrial Applications Charlie Barnes & Andy Carson Del Mar Ventures

2. Femtosecond Products Offered ByDel Mar Ventures • Pulse Pickers • Femtosecond Autocorrelators • Femtosecond Fluorescence Systems • Wavelength Converters • Ti:Sapphire Lasers • Ti:Sapphire Multipass Amplification Systems • Cr:Forsterite Lasers and TW Systems

3. Introduction to Cr:F Lasers • Center wavelength of 1250 nm • Tunable from 1100—1400nm • Broadband absorption • Directly pumped by Ytterbium Fiber Laser • Sensitive to thermal effects

4. Continuous Beam vs. Ultrashort Pulses Continuous Beam (Ideal Case)  Ultrashort Pulses (Ideal Case) 

5. Short Pulses vs. Long Pulses  

6. Out of phase Time Mode-locking Multimode Lasers RANDOM phase for all the laser modes Irradiance vs. Time Time

7. Mode-locking Multimode Lasers LOCKED phases for all the laser modes In phase Irradiance vs. Time Out of phase Out of phase Time Time

8. Mode-locked pulses Ultrafast lasers have thousands of modes!

9. High-intensity ultrashort pulse Focused pulse How do we mode-lock the laser?Kerr-Lensing Kerr medium (n = n0 + n2I) Low-intensity beam

10. Making a mode-locked laser Barrier CW Power Highloss Time c/2l Pulsed Power Time Lowloss

11. Elements of Cr:F ultrafast laser Output Coupler High Reflector Lens Curved Mirrors Yb:fiber Pump Laser Cr:F Laser Crystal Dispersion Compensating Prisms High Reflector

12. Pump Laser • Yb:fiber pump laser • Extremely compact size • No mode-beating • Noise level < 0.1% • Longer lifetime • Costs 50% less than comparable Nd:YAG

13. Chirped Pulse Amplification Oscillator Stretcher Amplifier Compressor

14. TerraWatt System Pump Laser: PYL-10 1060 nm, 10 W 1250 nm 40- 80 fs 100 МHz 2 nJ Pump Laser:1060 nm 30 ns, 30 mJ, 10 Hz Oscillator Stretcher Regenerative Amplifier Pump Laser: 1060 nm 30 ns, 0.7 J, 10 Hz Pump Laser: 1060 nm 30 ns, 1 J, 10 Hz 1250 nm 200 ps 10 Hz 0.5 mJ 1250 nm 200 ps 10 Hz 50 mJ Multipass Amplifiers 1250 nm 60 – 80 fs, 10 Hz, 120 mJ 1 – 2 TW Compressor 1250 nm 200 ps, 10 Hz, 200 mJ

15. Research and Industrial Applications • High Resolution Imaging • Photochemistry And Photobiology • Material Processing • Medical Applications • High Energy Physics

16. Advantages Femtosecond Lasers • Short pulse duration • Broadband • Very high resolutions • Less dispersion

17. Emission Spectra Cr:Forsterite Ti:Sapphire Cr:Forsterite Cr:YAG 800 nm 1250 nm 1500 nm

18. Advantages Cr4+:Fosterite Ti:Sapphire Cr:Forsterite Cr:YAG

19. Cr4+:Fosterite High speed communications Attenuation Dispersion

20. Non Linear Effects in vivo Significantly improve the depth resolution Imaging with Ultrashort Laser Pulses

21. Multi-Photon Microscopy t t Two photon fluorescence Three photon fluorescence Third harmonic generation

22. Third Harmonic Imaging High intensities create non-linear optical effects THL both sides of focus THL destructively interferes Index change breaks symmetry

23. Interfaces Third Harmonic Imaging

24. 125 µm THG Optical fiber in index-matching fluid Neurons 15 µm D. Yelin and Y. Silberberg

25. Optical Coherence Tomography • Micron-scale cross-sectional • in vivo imaging • Real time

26. Source Sample  / 2 Low Coherence Interferometry Michelson Interferometer Reference Detector Low-Coherence Source High-coherence Source Coherence Length Detector Detector Mirror Displacement Mirror Displacement

27. OCT Images Live Tadpole Blood Vessel

28. Most chemical reactions occur in 10-15 sec Femtosecond spectroscopy monitoring reactions in real time Short pulse duration allows the detection short-lived transient chemical reactions Femtosecond Spectroscopy

29. Medium is excited with femtosecond pulse Delayed probe pulse by increasing path length (microns) Short pulse duration allows short-lived reactions to be studied Very high resolutions Pump and Probe

30. Material Processing • High peak power, TW with amplified systems • Mulitphoton absorption • Low thermal and mechanical side effects • Ablation • Induced structural changes

31. e- Material Ablation Photons generate electrons 2) Electron avalanche 3) Plasma expansion 4) Electron-phonon coupling 5) Material is ejected

32. Variety of materials including dielectrics, semiconductors, metals, plastics Multiphoton absorption allows for processing of materials that are not very photosensitive. Material Processing 200 fs pulse 2.3 ps pulse (Herbert Welling, Laser Zentrum Hannover)

33. What can we make? • Micro gratings and periodic nanostructures • Machined parts for industrial and medical applications • Subsurface wave guides and all optical components

34. Medical • Laser Surgery • Medical biopsy • Hard tissue processing

35. Corneal flap removal in LASIK (Gerard Morou, University of Michigan)

36. Applications in dentistry • Alternative to mechanical drills and CW lasers • Reduced thermal stress • And micro cracks in enamel

37. Femtosecond X-Ray Pulses • Femtosecond X-ray pulses probe core electronic levels • Indication of the structural changes • Femtosecond X-rays can be generated through scattering visible laser beams by high energy electrons.

38. Conclusion • Many industrial and research applications • High Resolution Imaging • Photochemistry And Photobiology • Material Processing • Medical Applications • High Energy Physics • Del Mar Ventures offers a wide variety of femtosecond products

39. Thank you for coming Charlie Barnes and Andy Carson Del Mar Ventures