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Dye laser
Dye lasers use an organic dye dissolved in a liquid as the active lasing medium and can produce a wide range of wavelengths. They work on the principle of population inversion using a pumping source like a flash lamp or other laser to excite the dye molecules. The major components are the active dye medium, pumping source, and resonator mirrors, with one mirror sometimes replaced by a diffraction grating to allow tuning of the output wavelength. Dye lasers offer tunability but have limitations in lifetime and output power.
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Dye laser
- 1. DYE LASER Working principle Majorcomponents Construction Advantages Disadvantages Applications
- 2. A laser whichuses 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. Working Principle Itworks 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. Major Required Components 1.Active/Lasing Medium 2. Pumping Source 3. Resonator
- 5. Active Medium Activemedium for dye laser is the organic dye.it 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. Active medium(cont’) Organic dye + Water,Benzene,Ethanole.t.c = Active Medium Concentration of dye solution is kept around 10e-2 to 10e-4 Mole.
- 7. Pumping Source/Excitation Lasers Energyto 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. 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. Resonator Resonators areMirrors. 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.
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- 12. Emission Emission canbe 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.
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- 15. Advantages Low costTuning possible with multiple means No degradation of the optical properties of the organic dye. More robust(professional) and compact systems.
- 16. Disadvantages limited lifetime. limited output power
- 17. Applications Dye lasersare used to spectroscopy, holography and in Medical applications. A recent application of dye laser was in isotope separation.