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Dye Laser


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basic operation and roles of packaging

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Dye Laser

  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
  3. 3. The dyes used in these lasers contain rather large organic molecules which fluoresce. The incoming light excites the dye molecules into the state of being ready to emit stimulated radiation, the singlet state. In this state, the molecules emit light via fluorescence, and the dye is transparent to the lasing wavelength. Within a microsecond, or less, the molecules will change to their triplet state.
  4. 4. In the triplet state, light is emitted via phosphorescence, and the molecules absorb the lasing wavelength, making the dye opaque. Liquid dyes also have an extremely high lasing threshold. Flashlamp pumped lasers need a flash with an extremely short duration, to deliver the large amounts of energy necessary to bring the dye past threshold before triplet absorption overcomes singlet emission. Dye lasers with an external pump laser can direct enough energy of the proper wavelength into the dye with a relatively small amount of input energy, but the dye must be circulated at high speeds to keep the triplet molecules out of the beam path.
  5. 5. All dye lasers share the same active medium,they differ widely in internal structure. The pump source strongly influences design of dye laser because of the energy transfer kinetic of the dye The upper laser level has a lifetime of a few nanoseconds,making the pulsedye laser a high gain high loss system when it is pumped by pulses with high peak power. Pumping is more difficult with a continuous wave laser which does not generate high peak power in pulses To reach the high power densities needed to exceed laser threshold, the moderate power beam from continuous wave pump laser must be focused very tightly,concentrating its power in a small volume. The continuous wave pumped dye laser remains a low gain low loss system . Mode locking or cavity dumping allow a continuously pumped dye laser to generate pulsed output.
  6. 6. flashlamp or an external laser is usually used for “pump” purpose. Mirrors are also needed to oscillate the light produced by the dye’s fluorescence, which is amplified with each pass through the liquid. prism or diffraction grating is usually mounted in the beam path, to allow tuning of the beam. (which consists of two mirrors, which may be flat or curved, mounted parallel to each other with the laser medium in between. Tuning is used to adjust the wavelength) The dye cell is usually side-pumped, with one or more flashlamps running parallel to the dye cell in a reflector cavity. (dye-container) dye is a colored substance that has an affinity to the substrate to which it is being applied as lasing medium (ex: Rhodamine 6G)
  7. 7. The reflector cavity is often water cooled, to prevent thermal shock in the dye caused by the large amounts of near-infrared radiation which the flashlamp produces. output coupler (OC) is a partially reflective mirror used in lasers to extract a portion of the laser beam from the optical resonator. etalon forms the basis of wavelength locking system that can be used to stabilized the wavelength of a laser Beam expanding optic illuminates the whole width of a diffraction grating A cylindrical lens (focusing optic) is used to focus light which passes through on to a line instead of on to a point
  8. 8. Low cost Tuning possible with multiple means No degradation of the optical properties of the organic dye More robust and compact systems
  9. 9. limited lifetime. limited output power