Table of Contents
- 1 What is lasing action in laser?
- 2 Which process is used in lasing action?
- 3 What is the basic principle of laser action?
- 4 How does lasing occur?
- 5 What are the three main characteristics of laser light?
- 6 What is the minimum condition for lasing action?
- 7 How does lasing start in a medium?
- 8 What happens when lasing is initiated in a laser?
- 9 How are photons involved in the lasing process?
- 10 What does the term four level lasing mean?
What is lasing action in laser?
The actual process that occurs during the production of a beam of laser light is known as lasing process. The action which generates the laser light takes place within few nanoseconds.
Which process is used in lasing action?
We may conclude that, laser action is preceded by three processes, namely, absorption, spontaneous emission and stimulated emission – absorption of energy to populate upper levels, spontaneous emission to produce the initial photons for stimulation and finally, stimulated emission for generation of coherent output or …
What is a lasing system?
The active laser medium (also called gain medium or lasing medium) is the source of optical gain within a laser. The gain results from the stimulated emission of photons through electronic or molecular transitions to a lower energy state from a higher energy state previously populated by a pump source.
What is the basic principle of laser action?
Principle: Due to stimulated emission the photons multiply in each step-giving rise to an intense beam of photons that are coherent and moving in the same direction. Hence the light is amplified by Stimulated Emission of the Radiation.
How does lasing occur?
Lasing occurs when the radiation losses are compensated by the amplification of light in the active medium. Note that due to the spontaneous emission, an amplified spontaneous emission (ASE) takes place in the active medium below the lasing threshold19.
What makes a good lasing medium?
Relevant Physical Properties of Laser Gain Media a high transparency of the host medium in this wavelength region. a pump wavelength for which a good pump source is available (in case of an optically pumped laser); efficient pump absorption.
What are the three main characteristics of laser light?
Properties of laser light are: monochromacity (the same color), coherence (all of the light waves are in phase both spatially and temporally), collimation (all rays are parallel to each other and do not diverge significantly even over long distances).
What is the minimum condition for lasing action?
The minimum requirement for stimulated emission and amplification, or laser action, is that at least one higher energy level must have a greater population than a lower level.
What is the process of laser?
A laser is created when the electrons in atoms in special glasses, crystals, or gases absorb energy from an electrical current or another laser and become “excited.” The excited electrons move from a lower-energy orbit to a higher-energy orbit around the atom’s nucleus. Second, laser light is directional.
How does lasing start in a medium?
The active medium can be in a gaseous, liquid or solid form. For lasing to take place, the active medium must be pumped into an excited state capable of undergoing stimulated emission. The energy required for excitation is often supplied by an electric current or an intense light source, such as a flashlamp.
What happens when lasing is initiated in a laser?
Once the lasing action is initiated, the process of stimulated emission and the mechanism of positive feedback in the cavity take over, leading to steady-state laser oscillations.
When does the lasing occur between 2 and 1?
The lasing transition occurs between ‘2’ and ‘1.’ Because the initial population of level ‘1’ is very small, a population inversion is easily produced between the lasing levels. In reality, one or more of the levels may have a band structure, where a band is made up of a large number of levels bunched together.
How are photons involved in the lasing process?
Most of these photons are ineffective in the process that builds up the laser oscillations. Only a few of these—namely, the ones with their wave vectors along the axis of the optical cavity—get trapped in it and initiate the lasing action.
What does the term four level lasing mean?
Incidentally, the term ‘four level’ is commonly used to refer to a broad class of energy level schemes—namely, the ones in which the lower of the two lasing levels is almost empty, so that a population inversion can be achieved easily.
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