Your SlideShare is downloading. ×
0
<ul><li>LASER </li></ul>
Stimulated emission Spontaneous emission L ight  A mplification by  S timulated  E mission of  R adiation
Energy level diagram <ul><li>The possible energies which electrons in the atom can have is depicted in an energy level dia...
<ul><li>In 1958, Charles Townes and Arthur Schawlow theorized about a visible laser, an invention that would use infrared ...
T he operation of the Laser
T he operation of the Laser (Pumping the Laser)
T he operation of the Laser absorption
T he operation of the Laser Spontaneous emission
T he operation of the Laser Spontaneous emission <ul><li>Incoherent light </li></ul><ul><li>Accidental direction </li></ul>
T he operation of the Laser
T he operation of the Laser Stimulated emission
T he operation of the Laser Light: Coherent, polarized The stimulating and emitted photons have the same: frequency phase ...
Two level system absorption Spontaneous emission Stimulated emission h  h  h  E 1 E 2 E 1 E 2 h  =E 2 -E 1
<ul><li>n 1   -  the number of electrons of energy  E 1 </li></ul><ul><li>n 2   -  the number of electrons of energy  E 2 ...
Einstein’s coefficients   Probability of stimulated absorption R 1-2   R 1-2  =    (  ) B 1-2    Probability of stimulat...
B 1-2 /B 2-1  = 1   <ul><li>According to Boltzman statistics: </li></ul><ul><li>  </li></ul><ul><li>  </li></ul><ul><li>  ...
<ul><li>The probability of spontaneous emission A 2-1  /the probability of stimulated emission  B 2-1  (  : </li></ul>...
Condition for the laser operation If   n 1  >  n 2 <ul><li>radiation is mostly absorbed absorbowane </li></ul><ul><li>spon...
How to realize the population inversion? Thermal excitation:  Optically,   electrically . impossible. The system has to be...
Measurement disturbes the system The Uncertainty Principle
The Uncertainty Principle <ul><li>Classical physics </li></ul><ul><ul><li>Measurement uncertainty is due to limitations of...
The Uncertainty Principle <ul><li>Virtual particles: created due to the UP </li></ul>
Three level laser The laser operation E 1 E 3 E 2 Fast transition Laser action <ul><li>1  3  pumping </li></ul><ul><li>sp...
E 1 E 3 E 2 szybkie przejścia akcja laserowa - optical pumping - occupation of E3  of a short life time,  10-8s. It is a b...
 
ruby laser <ul><li>discovered in 60-ies of the XX century . </li></ul><ul><li>ruby (Al 2 O 3 ) monocrystal, Cr   doped . <...
<ul><li>Akcja laserowa z jonów  Cr 3+ ,  zawartych w rubinie  . </li></ul><ul><li>Laser trzypoziomowy . </li></ul><ul><li>...
Ruby laser First laser:  Ted Maiman Hughes Research Labs 1960
Upcoming SlideShare
Loading in...5
×

Laser

743

Published on

Published in: Technology, Business
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total Views
743
On Slideshare
0
From Embeds
0
Number of Embeds
1
Actions
Shares
0
Downloads
70
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide

Transcript of "Laser"

  1. 1. <ul><li>LASER </li></ul>
  2. 2. Stimulated emission Spontaneous emission L ight A mplification by S timulated E mission of R adiation
  3. 3. Energy level diagram <ul><li>The possible energies which electrons in the atom can have is depicted in an energy level diagram. </li></ul>
  4. 4. <ul><li>In 1958, Charles Townes and Arthur Schawlow theorized about a visible laser, an invention that would use infrared and/or visible spectrum light. </li></ul><ul><li>L ight A mplification by S timulated E mission of R adiation- ( LASER ). </li></ul><ul><li>Properties of Lasers </li></ul><ul><ul><li>Produce monochromatic light of extremely high intensity. </li></ul></ul>T he operation of the Laser
  5. 5. T he operation of the Laser
  6. 6. T he operation of the Laser (Pumping the Laser)
  7. 7. T he operation of the Laser absorption
  8. 8. T he operation of the Laser Spontaneous emission
  9. 9. T he operation of the Laser Spontaneous emission <ul><li>Incoherent light </li></ul><ul><li>Accidental direction </li></ul>
  10. 10. T he operation of the Laser
  11. 11. T he operation of the Laser Stimulated emission
  12. 12. T he operation of the Laser Light: Coherent, polarized The stimulating and emitted photons have the same: frequency phase direction
  13. 13. Two level system absorption Spontaneous emission Stimulated emission h  h  h  E 1 E 2 E 1 E 2 h  =E 2 -E 1
  14. 14. <ul><li>n 1 - the number of electrons of energy E 1 </li></ul><ul><li>n 2 - the number of electrons of energy E 2 </li></ul>Boltzmann’s equation example: T=3000 K E 2 -E 1 = 2.0 eV E 1 E 2
  15. 15. Einstein’s coefficients   Probability of stimulated absorption R 1-2 R 1-2 =  (  ) B 1-2   Probability of stimulated and spontaneous emission : R 2-1 =  (  ) B 2-1 + A 2-1   assumption: n 1 atoms of energy  1 and n 2 atoms of energy  2 are in thermal equilibrium at temperature T with the radiation of spectral density  (  ):   n 1 R 1-2 = n 2 R 2-1 n 1  (  ) B 1-2 = n 2 (  (  ) B 2-1 + A 2-1 )     E 1 E 2
  16. 16. B 1-2 /B 2-1 = 1 <ul><li>According to Boltzman statistics: </li></ul><ul><li>  </li></ul><ul><li>  </li></ul><ul><li>  </li></ul><ul><li>  </li></ul><ul><li> (  ) = = </li></ul><ul><li>  </li></ul><ul><li>  </li></ul>            Planck’s law
  17. 17. <ul><li>The probability of spontaneous emission A 2-1 /the probability of stimulated emission B 2-1  (  : </li></ul><ul><li>   </li></ul><ul><li>Visible photons, energy: 1.6eV – 3.1eV. </li></ul><ul><li>kT at 300K ~ 0.025eV. </li></ul><ul><li>stimulated emission dominates solely when h  /kT <<1! </li></ul><ul><li>(for microwaves: h  <0.0015eV) </li></ul><ul><li>  </li></ul><ul><li>The frequency of emission acts to the absorption: </li></ul><ul><li>  </li></ul><ul><li>  </li></ul><ul><li>if h  /kT <<1 . </li></ul>  x ~ n 2 /n 1      
  18. 18. Condition for the laser operation If n 1 > n 2 <ul><li>radiation is mostly absorbed absorbowane </li></ul><ul><li>spontaneous radiation dominates . </li></ul><ul><li>most atoms occupy level E2, weak absorption </li></ul><ul><li>stimulated emission prevails </li></ul><ul><li>light is amplified </li></ul>if n 2 > > n 1 - population inversion Necessary condition: population inversion E 1 E 2
  19. 19. How to realize the population inversion? Thermal excitation: Optically, electrically . impossible. The system has to be „pumped” E 1 E 2
  20. 20. Measurement disturbes the system The Uncertainty Principle
  21. 21. The Uncertainty Principle <ul><li>Classical physics </li></ul><ul><ul><li>Measurement uncertainty is due to limitations of the measurement apparatus </li></ul></ul><ul><ul><li>There is no limit in principle to how accurate a measurement can be made </li></ul></ul><ul><li>Quantum Mechanics </li></ul><ul><ul><li>There is a fundamental limit to the accuracy of a measurement determined by the Heisenb e rg uncertainty principle </li></ul></ul><ul><ul><li>If a measurement of position is made with precision  x and a simultaneous measurement of linear momentum is made with precision  p, then the product of the two uncertainties can never be less than h/ 2  </li></ul></ul>
  22. 22. The Uncertainty Principle <ul><li>Virtual particles: created due to the UP </li></ul>
  23. 23. Three level laser The laser operation E 1 E 3 E 2 Fast transition Laser action <ul><li>1  3 pumping </li></ul><ul><li>spontaneous emission 3  2. </li></ul><ul><li>state 2 is a metastable state </li></ul><ul><li>population inversion between states 2 and 1. </li></ul><ul><li>stimulated emission between 2 i 1. </li></ul>
  24. 24. E 1 E 3 E 2 szybkie przejścia akcja laserowa - optical pumping - occupation of E3 of a short life time, 10-8s. It is a band, the metastable and ground states are narrow : -  electrons are collected on E2: population inversion -   stimulated emission (one photon emitted spontaneously starts the stimulated radiation ) - Beam of photons moves normally to the mirrors – standing wave. The laser operation
  25. 26. ruby laser <ul><li>discovered in 60-ies of the XX century . </li></ul><ul><li>ruby (Al 2 O 3 ) monocrystal, Cr doped . </li></ul>
  26. 27. <ul><li>Akcja laserowa z jonów Cr 3+ , zawartych w rubinie . </li></ul><ul><li>Laser trzypoziomowy . </li></ul><ul><li>optical pumping: 510-600nm and 360-450nm . </li></ul><ul><li>fast transition on 2 E. </li></ul><ul><li>lasing: 2 E on 4 A 2, </li></ul><ul><li>694nm </li></ul>rapid decay Ruby laser Al 2 O 3 Cr + Energy 4 A 2 4 T 2 4 T 1 2 T 2 2 E LASING
  27. 28. Ruby laser First laser: Ted Maiman Hughes Research Labs 1960
  1. A particular slide catching your eye?

    Clipping is a handy way to collect important slides you want to go back to later.

×