I wonder if the following "image amplification" idea would work.
For instance, imagine observing the sky and you are interested for the H-alpha at 656nm wavelength. As there is low signal level, you have to do a long exposure and would also eventually get a high background noise..
Add an array of amplification medium (656nm laser diode array without OC and HR mirrors) to the front of every CCD/CMOS pixel. Every time a 656nm photon hits the given array element, it will be amplified, so you get a larger signal on your sensor. Other wavelengths wouldn`t be amplified so it works also as a very narrow band pass filter.
Using a similar design but somewhere at the night sky glow wavelength, one could build a night vision kit.
There must be a lot of practical or theoretical issues, I wonder what these are. Let me know your thoughts.
The problem is noise - it is going to be very high due to spontaneous emission inside the laser. On another hand, excellent single photon detector which can be tightly arrayed already exist, e.g. SPAD arrays https://www.laserfocusworld.com/detectors-imaging/article/14174261/photoncounting-camera-has-megapixel-spad-array-for-singlephoton-tof-and-other-imaging
The ASE gives a base level offset which could be handled with a ND filter. At single photon level it would just generate noise, you are right.
I like the SPAD array idea, I would have expected larger dark current from it. The disadvantage (or advantage) against the optical amplification that it would need an extra filter to make it wavelength selective.
Daniel Csati The spontaneous emission is highly random (Poisson) process, so statistical variations of it cannot be cancelled. On another hand, one indeed may consider practical short range lidar based on superregenerative laser e.g. you may check
"An example of double-pulsed supperegenerrative conditions in small VCSEL array "
- DOI:10.13140/RG.2.2.14064.30729
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