Fig. 1. Gold nanoparticles of four different mass fractions

Fig. 2. Diagram of experimental device

Fig. 3. Laser coupled into the fiber through a planoconvex lens

Fig. 4. Excitation and detection of ultrasound in the water tank

Fig. 5. Reference groups of two slides

Fig. 6. Spectra of Au NPs mixture with 0.47% concentration of gold nanoparticles at different laser energies

Fig. 7. Spectra of Au NPs mixture with 0.86% concentration of gold nanoparticles at different laser energies

Fig. 8. Spectra of Au NPs mixture with 1.79% concentration of gold nanoparticles at different laser energies

Fig. 9. Spectra of Au NPs mixture with 3.75% concentration of gold nanoparticles at different laser energies

Fig. 10. Spectra of Au NPs of various mass fractions at different laser frequencies

Fig. 11. Waveform of different concentrations of Au NPs under laser exposure of 50 mJ and 1 Hz

Fig. 12. Spectra of Au NPs with different concentrations under laser exposure of 50 mJ and 1 Hz

Fig. 13. Comparison of spectra of gold nanoparticle with different thickness

Fig. 14. Comparison of two photoacoustic materials in time domain and frequency domain