LASER

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1. laser MUHAMMAD UMAIR

2. Pumping Processes

3. Laser Safety Rules 1) Wear special goggles. 2) Never looking the primary laser beam or into the specular reflection of a beam. 3) Higher power beams should be terminated. 4) Skin protection should be worn at higher power levels ( e.q . heavy white cloth ) 5) Special precaution for invisible laser beam.

4. history The technique was developed by 1966  Nobel Prize  winner  Alfred Kastler  in the early 1950s. Alfred Kastler . The  Nobel Prize  in Physics  1966  was awarded to  Alfred Kastler for  the discovery and development  of  optical methods  for  studying Hertzian resonances in atoms.

5. Article published For his article that was published Read more at:  https:// http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.731.123&rep=rep1&type=pdf

6. Pumping and laser pumping Pumping is a process done by a device that raises, transfers, delivers, or compresses fluids or that attenuates gases especially by suction or pressure or both. Laser pumping  is the act of energy transfer from an external source into the gain medium of a laser. The energy is absorbed in the medium, producing excited states in its atoms. When the number of particles in one excited state exceeds the number of particles in the ground state or a less-excited state, population inversion is achieved. In this condition, the mechanism of stimulated emission can take place and the medium can act as a laser or an optical amplifier. Light is amplified when the population inversion is positive. The pump energy is usually provided in the form of light or electric current.

7. Optical pumping Optical pumping is a process in which light energy is used to excite electrons from a lower to higher energy level. It was first developed by Alfred Kastler in the early 1950s. Optical pumping often takes place in laser action which involves absorption of photons of light to raise the energy levels of electrons. These electrons remain at higher energy state until they are activated to release their stored energy in the form of a laser beam. Several types of lasers can be optically pumped. The most common optically pumped lasers are doped-insulator solid-state lasers.

8. Optical pumping Some of the common optical pump sources include: Laser diodes Discharge lamps Other types of laser sources such as dye lasers pumped with gas lasers and titanium-sapphire lasers pumped with solid-state lasers

9. Flash lamp and laser Laser Flash Lamps  or Gas discharge   laser lamps are used as optical pump sources for solid state  lasers . The two main categories of  laser  pump lamps  are DC arc lamps  for continuous pumping Laser flash lamps  for pulsed pumping

10. Threshold pump power The pump power for which the  Laser  threshold is reached. The threshold pump power of an optically pumped laser is the value of the pump power for which the laser threshold is just reached. At this point, the small-signal  Gain  equals the losses of the laser. . A similar threshold exists for some other types of  Light  sources, such as e.g.  Raman Lasers . Raman Lasers is now the days are used in instrument of solid state technique named as RAMAN SPECTROSCOPY , every Physicst is familiar with this Technique.

11. Pumping efficiency

12. Electrical pumping In this method of  pumping ,  electric  discharge acts as the  pump  source or energy source. A high voltage  electric  discharge (flow of electrons,  electric  charge, or electric  current) is passed through the laser medium or gas.

13. That we know? What is longitudinal wave and transverse wave ?

14. Longitudinal configuration/modes The operating modes of a physical system are formed by physical laws and boundary conditions. . The superimposed waveforms that form the mode move with a fixed velocity that is dependant on the properties of the system, and have wavelengths equal to 2L/n, where L is the length of the string, and n is a positive integer. These are the  modes  of the system. The longitudinal configuration or modes determines the emission spectrum of the laser . The light bouncing repeatedly off the end mirrors set up standing waves inside the cavity.

15. Longitudinal configuration/modes

16. Transverse configuration A  transverse mode  of a beam of electromagnetic radiation is a particular electromagnetic field pattern of radiation measured in a plane perpendicular to the propagation direction of the beam. Transverse modes occur in  radio  waves and microwaves confined to a waveguide, and also in light waves in an  optical fiber . Types of modes Unguided electromagnetic waves in free space, can be described as a superposition of plane waves; these can be described as TEM modes as defined below. Transverse electromagnetic (TEM) modes: neither electric nor magnetic field in the direction of propagation. Hybrid modes: non-zero electric and magnetic fields in the direction of propagation.

17. Configuration

18. How we get TEM IMAGES? By a well known technique TEM. TEM-T ransmission electron microscope, that is used to view thin specimens (molecules, etc) through which electrons can pass and generating a projection image. 

19. TEM-Transmission electron microscopy

20. TEM-IMAGES

21. Gas dynamic pumping Gas dynamic lasers  are constructed using the supersonic flow of gases, such as carbon dioxide, to excite the molecules. A  gas dynamic laser  ( GDL ) is a  laser  based on differences in relaxation velocities of molecular vibrational states. 

22. chemical pumping Chemical pumps  are used to transfer  chemicals  and are designed to be resistant to industrial liquids such as fuel, paint, bleach, solvents, etc. Chemical pumps  can be either centrifugal  pump  or a positive displacement  pump depending on the specific application. How do chemical lasers work and its uses? A  chemical laser  is a  laser  that obtains its energy from a  chemical  reaction. They are used in industry for cutting and drilling common. examples of chemical lasers  are the  chemical  oxygen iodine  laser  coil.

23. discussion

24. Individually Assignment task Q:- What is Optical resonators? Also distinguish its types. (Via Email) DEAD LINE TO SUBMIT ASSIGNMEN IS; 6-04-2019 till (12Am)

25. The end