How Does Continuous Lasing Action Work in Solid State Lasers Like Nd:YAG?

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Discussion Overview

The discussion centers on the mechanisms behind continuous lasing action in solid state lasers, specifically Nd:YAG lasers. Participants explore the implications of temperature on lasing conditions, the effects of thermal dynamics, and the concept of population inversion in relation to continuous operation.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions how Nd:YAG lasers can achieve continuous lasing action given that lower temperatures are typically considered optimal, especially since significant heat is generated during the pumping process.
  • Another participant challenges the assumption that Nd:YAG lasers cannot operate continuously, asking for clarification on the context of the initial claim.
  • A participant asserts that population inversion is a negative temperature process, suggesting that increased temperature could hinder population inversion and thus lasing action.
  • There is a query about the availability of a coolant that could effectively manage the temperature rise during continuous operation, or if there is an alternative explanation for the observed phenomena.
  • One participant discusses the thermal effects in laser systems, particularly thermal lensing and birefringence, noting that continuous operation is typically limited to low intensity to minimize heating effects.
  • Another participant emphasizes that population inversion should not be equated with temperature, as it represents a non-equilibrium state, which complicates the relationship between temperature and lasing efficiency.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between temperature, population inversion, and continuous lasing action. There is no consensus on the implications of thermal effects or the mechanisms that allow continuous operation in Nd:YAG lasers.

Contextual Notes

The discussion highlights limitations in understanding the thermal dynamics of solid state lasers, including the dependence on radiation intensity and the complexities of population inversion as it relates to temperature.

Rahul Manavalan
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Hello
I've been wondering how certain solid state lasers could have a continuous lasing action (Nd YAG laser for instance )
If so,the understanding that the best lasing conditions are when the temperature Is lowest gets disproved(considering that a commendable quantity of heat is produced during the pumping process!
Please help me with this idea and do correct me if I'm wrong!
 
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Rahul Manavalan said:
I've been wondering how certain solid state lasers could have a continuous lasing action (Nd YAG laser for instance )
Why not? What makes you think that a Nd:YAG laser cannot be operated in continuous mode?
Rahul Manavalan said:
the understanding that the best lasing conditions are when the temperature Is lowest gets disproved(considering that a commendable quantity of heat is produced during the pumping process!
In which context are you speaking of?
 
Isn't it a fact that the population inversion is known as a negative temperature process?
If yes,increase in temperature hampers population inversion and hence lasing action becomes invalid.
It's obvious that continuous operation of a krypton arc lamp generates tremendous heat.
My question is :is there a coolant that could bring down the temperature as quickly as it heats up?
Or is there an alternative explanation
 
Thermal effect does cause problem in a laser system, but this is mainly due to the thermal lensing where the index of refraction of the gain medium gets modified and photoelastic effect which can further cause birefringence effect. Heating process of the gain medium depends, among others, on the radiation intensity of the laser. Continuous operation is known to be limited to low intensity, due to this heating of the gain medium is supposed to be relatively minimal. For such low power laser system, air cooling (that is, the gain medium is simply exposed to an open space) is usually sufficient to prevent any pronounced thermal effects. Heating effect, instead, becomes serious in pulsed operation as the pulse intensity involved within the cavity may very high.
 
Thanks
It was very helpful
I owe you a big deal
 
You are welcome.
 
Also, keep in mind that population inversion should not be thought of as a temperature. The normal expression for temperature relates to to an average of an ensemble in equilibrium, but a population inversion is NOT in equilibrium. Even though you could still ascribe it a temperature it doesn't mean the same thing.
 
Thanks Zarqon
 

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