Fig. 3. Thermal one-side coherent perfect absorption (CPA).

The ring-shaped object has an arbitrary thermal conductivity κ that is (a, c) larger or (b, d) smaller than that of the background κ₀. a, b The temperature distributions on the entire system with isothermal lines (white). c, d Temperature distributions along the line h = 0. The regions of the background (beige) and the object (light blue) are shaded. The incident fields input-1 (red) and input-2 (blue) are also plotted. For one-side CPA only the field outside the object meets the input field. e The required inputs (black) and the reflection (blue) and transmission (red) coefficients for different combinations of the object and background materials.