Dear researchers
It's well-known that the maximum light absorption of any structure can not be greater than 50%.
Is it possible that the single-pass absorption exceeds 50%? How?
"Absorption" of what? Light? or other?
You should be somewhat more specific in your question
Giuseppe Curro
Yes, I mean light absorption. the question is tagged by optics
Ok. Now that it is clear you are referring to light absorption, can you tell me why do you think that the maximum absorption fraction is 50% for a generic structure ? By the way, I suppose you are talking of absorption in the UV-Vis-NIR spectral range.
Giuseppe Curro
Hi, thanks for your answer. this fact was proved in the following paper:
Article Total Absorption in a Graphene Monolayer in the Optical Regi...
Proof: It has long been known that the maximum single-pass absorption of a thin absorbing layer in air is 50%.26,27 The film in air is a two-port system. Light can be injected from either side of the structure; each side then constitutes a port. For a very thin film, one can understand the 50% absorption limit from a symmetry argument: a single wave incident from one side can be decomposed into a superposition between an even mode, where equal amplitude waves with the same phase illuminate the film from both sides, and an odd mode, where the two input waves are 180° out of phase. Only the even mode can contribute to the absorption: since the odd mode has vanishing fields at the thin film, it cannot contribute to the absorption. A wave incident from one side has equal power in the even and odd modes, and therefore the maximum absorption for single illumination cannot exceed 50%.
Fathi Mohammed
Hi, thanks for your answer. this fact was proved in the following paper:
Article Total Absorption in a Graphene Monolayer in the Optical Regi...
Proof: It has long been known that the maximum single-pass absorption of a thin absorbing layer in air is 50%.26,27 The film in air is a two-port system. Light can be injected from either side of the structure; each side then constitutes a port. For a very thin film, one can understand the 50% absorption limit from a symmetry argument: a single wave incident from one side can be decomposed into a superposition between an even mode, where equal amplitude waves with the same phase illuminate the film from both sides, and an odd mode, where the two input waves are 180° out of phase. Only the even mode can contribute to the absorption: since the odd mode has vanishing fields at the thin film, it cannot contribute to the absorption. A wave incident from one side has equal power in the even and odd modes, and therefore the maximum absorption for single illumination cannot exceed 50%.
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