Comparing Atomic Gas and Semiconductor Lasers

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Discussion Overview

The discussion focuses on the quantitative differences between the light produced by atomic gas lasers and semiconductor lasers, exploring aspects such as power, coherence, and beam quality. The conversation includes technical comparisons and implications for applications.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants note that atomic gas lasers produce low power but high collimation, while semiconductor lasers are associated with higher power due to stimulated emission.
  • One participant claims that the light from both types of lasers cannot be distinguished, attributing differences primarily to the cavity design and noting the absence of spectral or spatial hole burning in gas lasers.
  • Another participant highlights that the coherence length of a gas laser can extend to tens of meters, in contrast to a laser diode, which has a coherence length around 1 mm.
  • It is mentioned that diode lasers can achieve reasonable coherence lengths (tens of centimeters) but are sensitive to temperature and can experience issues with backscattered light.
  • Participants discuss that traditionally, high power was associated with gas lasers, but advancements have led to the development of high-power diode lasers for applications like cutting and welding.
  • One participant asserts that while diode arrays can provide significant raw power, they often lack desirable characteristics such as good beam quality, low divergence, and long coherence length.

Areas of Agreement / Disagreement

Participants express differing views on the characteristics and performance of atomic gas lasers versus semiconductor lasers, indicating that multiple competing perspectives remain without a clear consensus.

Contextual Notes

The discussion includes assumptions about the definitions of power, coherence, and beam quality, which may vary between contexts. The implications of temperature sensitivity and engineering developments in diode lasers are also noted but not resolved.

Who May Find This Useful

This discussion may be of interest to those studying laser technology, optics, or applications in engineering and physics, particularly in understanding the comparative properties of different laser types.

hhhmortal
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Hi, I want to know what the important quantitative differences between the light produced by an atomic gas laser and that produced by a semiconductor laser are?

I know that produced my atomic gas lasers are low power but high collimation, but semiconductor lasers seem to have higher power? because of stimulated emission?


Thanks.
 
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You cannot distinguish the light of the two lasers. The properties are mostly set by the cavity. The main difference is, that there is no spectral or spatial hole burning in gas lasers because the particles are moving around.
 
The coherence properties of a diade and a gas lasers differ quite a lot. The coherence length of a laser diode is around 1 mm whilst a gas laser can extend tens of meters
 
Diode lasers can have reasonable coherence lengths (few 10s cm) but are very temperature sensitive, you can also have problems if any of the light is scattered back into the diode.

Traditionally if you wanted high power you needed gas lasers, but engineering convenience means that people have developed few x 10KW diode lasers for cutting/welding
For all you want to know about lasers see http://www.repairfaq.org/sam/laserdio.htm
 
Last edited:
If you need raw power nothing (almost) beats a good diode array. Unfortunately, diode lasers don't easily provide some other desirable characteristics: good beam quality, low divergence, long coherence length.
 

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