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Dye laser


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Simple Illustration of Dye Laser.

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Dye laser

  1. 1. DYE LASER Working principle Major components Construction Advantages Disadvantages Applications
  2. 2. A laser which uses an organic dye as the lasing medium, usually as a liquid solution. A dye can usually be used for a much wider range of wavelengths. These Lasers were discovered by Sorokin and his colleagues. Q-What is a Dye? A dye is a colored substance which imparts(applies) its color to the material it is being applied.
  3. 3. Working Principle  It works on the principle of population inversion.  Q-What is Population Inversion?  To achieve optical amplification it is necessary to create a distribution of atoms such that the population of the upper energy level is greater than that of the lower energy level (i.e. N2 > N1). This condition is known as population inversion.
  4. 4. Major Required Components 1. Active/Lasing Medium 2. Pumping Source 3. Resonator
  5. 5. Active Medium  Active medium for dye laser is the organic is a liquid material.  Some of the Organic dyes are Rhodamine 6G (orange, 540–680 nm) also known as Xanthene dye , Fluorescein (green, 530– 560 nm), Coumarin (blue 490– 620 nm), Stilbene (violet 410– 480 nm), Umbelliferone (blue, 450– 470 nm), Tetracene, malachite green, and others.  Most Commonly used is Rhodamine 6G.  The organic dye is dissolved in solvents like: water,benzene,alcohol,ethanol.
  6. 6. Active medium(cont’) Organic dye + Water,Benzene,Ethanol e.t.c = Active Medium Concentration of dye solution is kept around 10e-2 to 10e-4 Mole.
  7. 7. Pumping Source/Excitation Lasers Energy to excite the dye is supplied by a strong light source that may be a flash lamp or other as listed below. Flash lamps and several types of lasers can be used to optically pump dye lasers. A partial list of excitation lasers include:  Copper vapor lasers  Diode lasers  Excimer lasers  Nd:YAG lasers (mainly second and third harmonics)  Nitrogen lasers  Ruby lasers  Argon ion lasers in the CW regime  Krypton ion lasers in the CW regime
  8. 8. Pumping Source/Excitation Lasers  Here the pumping source is a mono-chromatic laser(excimer laser).  Q-what is a pumping source?  To achieve Stimulated emission,we need more atoms in higher energy state(E2).This phenomenon is achieved by bombardment of photons.So pumping source is actually a source of Photons.
  9. 9. Resonator  Resonators are Mirrors. The most useful feature of dye Lasers is their tunability,means the lasing wavelength can be varied over a wide range.  Due to this reason ,dye lasers are also called Tunable Lasers.  One of the technique to obtain tuning is to replace one of the mirrors with Diffraction grating,by rotating the grating the wavelength of dye laser can be altered.Thus tunability is obtained.
  10. 10. Construction
  11. 11. Basics Absorption Emission (Intensity) Absorption Emission (m)
  12. 12. Emission  Emission can be of two types: 1. Fluorescence 2. Phosphorescence Fluorescence: It means when a photon hits dye,it immediately (zero time delay) emits light. Phosphorescence: In phosphorescence there will be some time delay. Both these Phenomenon occurs due to nature of different organic dyes.
  13. 13. Energy Level Diagram
  14. 14. Electromagnetic Spectrum Diagram
  15. 15. Advantages  Low cost Tuning possible with multiple means  No degradation of the optical properties of the organic dye.  More robust(professional) and compact systems.
  16. 16. Disadvantages  limited lifetime.  limited output power
  17. 17. Applications  Dye lasers are used to spectroscopy, holography and in Medical applications. A recent application of dye laser was in isotope separation.