0
$\begingroup$

Consider two light sources A and B. Exclude things like scattering. Without any kind of barrier A can send light to B and vice versa. I'm looking for some kind of material or setup where A can send to B but not B to A. I'm not much into physics and optics. I'm aware of one way mirrors but I don't know how much it blocks. Are there (practical) alternatives and how much of the reverse channel will they block?

$\endgroup$
  • $\begingroup$ Related (if not a duplicate): Is one way glass possible? $\endgroup$ – Ruslan Feb 20 at 13:02
  • $\begingroup$ Many variants of this question have been asked on this site previously. Please read them carefully; if they do not answer your query, please edit this post to explain what aspects are missing in the existing threads. $\endgroup$ – Emilio Pisanty Feb 20 at 13:09