# Is it possible to get a lasing from every luminescent media?

Let's assume that there is a cavity with a couple of mirrors and gain media between which possesses luminescence under some external excitation/pumping. Let the absolute quantum yield of the gain media be quite high - 50%, luminescence decay is approximately 100 µs and full width at half maximum is about 100 nm with maximum at 500 nm (something like blue-green light). All these parameters are quite real. So with such parameters what do we need to get lasing? And second question, what would the output spectrum look like?

• For lasing you need a population inversion, which may not be achievable in all system. On the other hand, as a laser jock once told me, anything will lase if pumped hard enough (but that is because you will get non-linear effects, overcoming the issues causing the problem in the first sentence). Jan 15 '16 at 17:55
• It's like with flying... you can make a barn door fly (I have seen that) or a lead cube (that I have not, but then, I have not been in the artillery), if you put a powerful enough engine on it. You don't need a cavity for a laser, either. The cavity is there to select a certain frequency, it's not essential for the amplification process. As for numerical predictions... that's not possible with your specifications. As Jon Custer said... one would need a level diagram of the system and a lot more information about the transitions. Jan 15 '16 at 18:18
• In addition, in many cases luminescent emission goes down to the ground state, so absorption directly competes with stimulated emission. That is, the medium itself has high losses that must be overcome. Jan 15 '16 at 18:22
• @CuriousOne The cavity also provides feedback for oscillation. The oscillation function and the frequency-filtering function are, of course closely related, but you can have a filter without the sustained oscillation. Jan 15 '16 at 18:25
• garyp :curiousone is correct. A reasonably long lasing medium will generate a coherent output if well-pumped. It doesn't require a source oscillator as does a laser amp. Jan 15 '16 at 19:39

• To be honest I skipped over that detail. I am not familiar with the abbreviation mks - milli kilo seconds sounds wrong. Can you please explain? Your title question was "every luminescent media", but you seem to be asking about a specific medium. Jan 15 '16 at 19:26