Dye Laser , Construction , Working , Advantages , Disadvantages , Applications

         -: Dye Laser :- 


A laser which uses an organic dye as the lasing medium usually as a liquid solution is called dye laser . 
                                The characteristics of dye laser given as - 
1- Dye Laser is a tunable laser  .
2- Dye Laser is a four -level liquid laser in which organic dye is used as a lasing medium . 
3- Dye Laser operates mostly in the visible spectrum . 
4- Dye Laser is optically excited by another laser . 
5- On the basis of pumping mode , it can emit radiation continuously or in pulsed modes . 
6- Dye Laser can generate radiation with narrow frequency spectrum . 

Construction :- 
                          In this laser system , organic dyes , the most important solids , dissolve in a suitable various types of solvents like alcohol , toluene , benzene , acetone , water etc at a concentration ratio 1:1000 . This shows that each molecule is surrounded by the molecules of solvent , the liquid is filled in a tube of 1 mm diameter which can be used as a laser medium instead of laser rods as in solid -state lasers . An optical cavity was formed by using confocal mirror arrangement . The tube filled with liquid is surrounded by a conventional spiral flash . The schematic diagram of dye laser is given as - 

Working :- There are two electronic sets of molecules one is singlet and other is triplet . Each electronic state contains several vibrational states . The separation between two neighboring vibrational states is of the order of 1000-2000 cm⁻¹ , whereas a typical energy separation between two singlet or two triplet states is about 10000-20000 cm⁻¹ .
                            Thus laser action takes place between vibrational sub-level and an excited sub-level as provided the population inversion exits between there two states . 

Advantages of Dye Laser :- The advantages of Dye laser are given as - 

1- A unique property of dye lasers is the broad emission spectrum (30-60 nm) over which the gain occurs . when this broad gain spectrum is combined with a diffraction grating or a prism as the cavity mirrors , the dye laser output can be a very narrow frequency beam ( 10 GHz or smaller ) . 
2- Dye Laser is the cheapest laser . 
3- It  is the most widely used tunable laser in visible range . 
4- It is used with very high gain and mode locked laser . 
5- Concentration can be controlled in this type of laser . 

Drawbacks of Dye Laser :- 

1- The excitation is done by another laser which complicates the system                                                 
2- The viscosity of liquid laser is also high , as a result circulating motion is not feasible . 
3- The quality of dry degrades with time and needs to be changed .

Application of Dye Laser :- 
1- Dye laser is used in the field of spectroscopy to separate isotopes. 
2- Dye Laser is used to retard atoms to very slow speeds . 
3- Dye laser is used in the study of dynamics of exited stated of semiconductors . 
4- It is also used in treatment of cancers .