Fig. 5.

Theoretical and experimental explorations in the application of thermal-based nonlinearity. (A) Theoretical results of PA signal as a function of temperature. Solid line: absorber with low $\text{Δ}T$. Dashed line: absorber with high $\text{Δ}T$. (B) Theoretical prediction linear and nonlinear PA–F curve at $T_0$=20 °C. (C) Experimental results of PA signal as a function of temperature. Circle: dye molecules. Cross: gold nanosphere. (D) Linear fit analysis for single voxel. R_lin for ink is considerably higher than R_lin for GNPs. Triangle: ink. Dot: gold nanosphere. (E) Plot of R_lin in an MAP image. (F) Plot of $a_2$ in an MAP image. Figures reproduced with publisher’s permission [30,32].