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Excimer and Dye lasers

Excimer and Dye lasers. Helga Dögg Flosadóttir Nútíma Ljósfræði Vor 2008. Outline. Excimer LASER Function Chemicals Characteristics Applications in industry and research Organic Dye LASER Chemicals Function Characteristics Applications in industry and research. Excimer LASER.

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Excimer and Dye lasers

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  1. Excimer and Dye lasers Helga Dögg Flosadóttir Nútíma Ljósfræði Vor 2008

  2. Outline • Excimer LASER • Function • Chemicals • Characteristics • Applications in industry and research • Organic Dye LASER • Chemicals • Function • Characteristics • Applications in industry and research

  3. Excimer LASER • N.G. Basov et al 1970 • First excimer laser • Xe(g) • 172 nm • Uversity of Cambridge, Kansas State University, Avco Everett Research laboratory, 1974 • First exciplex excimer lasers • Simulataneously • Lambda Physik 1977 • First commercial excimer/exciplex laser • 10 MW • Excimer • Function • Chemicals • Characteristic • applications • Organic Dye • Chemicals • Function • Characteristic • applications

  4. Excimer LASER • Excited dimer • Short lived molecule formed from one or two species, at least one of which is in an electronically excited state • May not be stable in ground state • Excimer LASER: • Electron pumped LASER • Dimer (excimer)/complex (exciplex) formation • LASER radiation: relaxation from excited state dimer to ground state • Excimer • Function • Chemicals • Characteristic • applications • Organic Dye • Chemicals • Function • Characteristic • applications

  5. Excimer e- + A → A* A* + B → AB* → AB + hν Immediately AB → A + B Two important facts: • The lower state does not exist! • No rotational/vibrational bands • Excimer • Function • Chemicals • Characteristic • applications • Organic Dye • Chemicals • Function • Characteristic • applications

  6. Excimer LASER Energy states of an excimer • Excimer • Function • Chemicals • Characteristic • applications • Organic Dye • Chemicals • Function • Characteristic • applications

  7. Excimer • Excited Dimers • F2, Xe2 ect. • Excited Complexes (Exciplex) • Combination of rare gas atoms and halogen atoms • Ar, Kr, Xe • F, Cl, Br • Excimer • Function • Chemicals • Characteristic • applications • Organic Dye • Chemicals • Function • Characteristic • applications

  8. Excimer LASER • Many wavelength possibilities • Depends upon the excited dimer • Repetition rate from 0.05 Hz to 20 kHz • High power: • several 10-200 W • Excimer • Function • Chemicals • Characteristic • applications • Organic Dye • Chemicals • Function • Characteristic • applications

  9. Excimer LASER • Micromaching • Ink jet cartidges (drilling the nozzles) • Radiation for changing the structure and properties of materials • Active matrix LCD monitors • Fiber bragg gratings • High temperature superconducting films • “Short wavelength light bulb” in optical litography • Computer chips • Excimer • Function • Chemicals • Characteristic • applications • Organic Dye • Chemicals • Function • Characteristic • applications

  10. Excimer LASER • Eye surgery for vision correction with ArF lasers at 193 nm • psoriasis treatment with XeCl lasers at 308 nm • Pumping dye lasers (XeCl) • Excimer • Function • Chemicals • Characteristic • applications • Organic Dye • Chemicals • Function • Characteristic • applications

  11. Outline • Excimer LASER • Function • Chemicals used • Characteristics • Applications in industry and research • Organic Dye LASER • Chemicals • Function • Characteristics • Applications in industry and research

  12. Dye LASER • Liquid LASERs • Organic dyes solved in organic solvents • Pumped with a LASER and emit light via fluoresence • Excimer • Function • Chemicals • Characteristic • applications • Organic Dye • Chemicals • Function • Characteristic • applications

  13. Dye LASER • Organic polyatomic molecules with conjugated π-chains • Rhodamine, tetracene, coumarine, stilbene and more. • Solvent • Methanol, ethanol, water or ethylene glycol • Additional chemicals added to prevent intersystem crossing and prohibit degration of the dye • Excimer • Function • Chemicals • Characteristic • applications • Organic Dye • Chemicals • Function • Characteristic • applications

  14. Dye LASER • Polyatomic organic molecules containing conjugated double bonds • Excimer • Function • Chemicals • Characteristic • applications • Organic Dye • Chemicals • Function • Characteristic • applications

  15. Dye LASER • Polyatomic organic molecules containing conjugated double bonds • Electrons move freely within the whole chain • Excimer • Function • Chemicals • Characteristic • applications • Organic Dye • Chemicals • Function • Characteristic • applications

  16. Dye LASER • Polyatomic organic molecules containing conjugated double bonds • Electrons move freely within the whole chain • Can be described as a free electron in one dimensional potential well • Excimer • Function • Chemicals • Characteristic • applications • Organic Dye • Chemicals • Function • Characteristic • applications

  17. Dye LASER En = h2N2/8mL2 • Excimer • Function • Chemicals • Characteristic • applications • Organic Dye • Chemicals • Function • Characteristic • applications

  18. Selection rule: ∆S = 0 S0 → S1 allowed Vibrational and rotational levels unresolved in liquid Fluorescence emission S1 → S0 Losses: Intersystem crossing S1 → T1 Phosphoresence T1 → S0 Absorption S1 → S2 T1 → T2 Dye LASER • Excimer • Function • Chemicals • Characteristic • applications • Organic Dye • Chemicals • Function • Characteristic • applications

  19. Dye LASER • Problems • Short lifetime of the S1 state • Intersystem crossing and long lifetime of T1 • Thermal gradients produce refractive gradient • Operation • Pulsed laser action • Circulation of dye solution • Pumping – another laser such as • Nitrogen laser (UV-visible) • Excimer laser (UV-visible) • Nd:YAG laser (visible) • Excimer • Function • Chemicals • Characteristic • applications • Organic Dye • Chemicals • Function • Characteristic • applications

  20. Dye LASER • Vibration and rotational energy levels not resolved • Broad emission spectrum • tunable • Wide selection of dyes for different emission wavelength ranges and absorbance • Very short pulses achievable • Excimer • Function • Chemicals • Characteristic • applications • Organic Dye • Chemicals • Function • Characteristic • applications

  21. Dye LASER • Academic • Tunable in a wide range of wavelengths • Environmental • Pollution monitoring • Excimer • Function • Chemicals • Characteristic • applications • Organic Dye • Chemicals • Function • Characteristic • applications

  22. Thank you!

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