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While most common lasers are electrically powered, there are also chemically powered lasers. These are high power systems, since for lower power systems electrically powered lasers (including optically pumped) are more practical. The chemistries I'm aware of (from wikipedia) use highly toxic fuels or have highly toxic reaction products. (Iodine based lasers that I could find use chlorine gas as an input, hydrogen fluoride lasers result in hydrogen fluoride.)

Are there any chemistries that could conceivably be used as a chemical laser that do not require handling of such dangerous compounds? (That preferably are usable at a smaller scale, although I am not aware of any reason why existing chemical lasers could not be used at small scales.)

edit: The question is just out of curiosity, for practical applications other types of lasers would be more useful.

JanKanis
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    If there were numerous reactions that produced excited states chemically then these might be of some use, but reactants are needed in huge quantities and so these types of lasers are v. expensive to run and of limited use anyway since there are alternative solid state lasers for most tasks nowadays. If you want to shoot down planes or satellites then multi-kw chemical lasers may be your only choice. (btw most lasers are optically pumped say from another laser, laser diode or flash lamps. Argon ion (gas) lasers are still electrically excited but these are rarely used nowadays due to cost). – porphyrin May 16 '20 at 15:24
  • @porphyrin Yes electrically powered (including with diodes, flash lamps) lasers are more practical at small scale, I'm just wondering if these chemical lasers need to use dangerous chemicals or if more safe-ish reactions could in theory also work. For a smaller laser you'd also need less chemicals. Or are you saying that the amount of reactant doesn't scale more or less linearly with the output power of a laser? – JanKanis May 16 '20 at 21:59
  • @EdV What do you base that conclusion on? Lack of googlable alternatives? I also considered that line of reasoning, but on the other hand, chemical lasers have only really been considered for the highest power regimes, where more energetic and thus dangerous compounds are preferable and the dangers can be managed by professionals. So there probably just hasn't been much research into safer chemistries. I'm also happy with answers that just 'in principle' could lead to laser action but which haven't been demonstrated. – JanKanis May 17 '20 at 07:54
  • I don't doubt their competence, but what did their design space and trade offs look like? My guess is that concerns like high output power were more important to them than chemical toxicity. – JanKanis May 18 '20 at 10:09

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Existing chemical lasers work fine on small scales. Usually they were developed at small scales and later scaled up.

Chemical fuels for lasers need high energy reactants in order to create excited states. High energy substances are often reactive, which makes them toxic as they will also react with human body components. Stable laser fuels also exist, in the form of regular hydrocarbon fuels. Many hydrocarbon fuels can be used to power CO₂ gas-dynamic lasers.

The reason iodine and hydrogen fluoride lasers are used is that these are the few types of chemistries that produce relatively short wavelength output. Most chemical reactions deposit their energy into rotational-vibrational exitation modes. These have a much lower energy than electronic exitation modes and will lase in the deep infrared. CO₂ gas dynamic lasers emit light in the 10 µm range. There has been research into other chemical laser pathways resulting in visible or near visible output, but so far without result as far as I was able to find. Some (old, 1980s) background: Technical Report JSR-80-14: Visible Chemcial Lasers

JanKanis
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