Fig. 5: Second-harmonic generation (SHG) enhancement of near-infrared laser pulses due to the stimulated phonon polariton-mediated light–matter interaction.

a Experimental setup for excitation of the stimulated phonon polaritons and the measurement of SHG signal of infrared laser pulses. CL: convex lens; LN: lithium niobate slab; BF: blue filter; SP: spectrometer; FP: focus plane; IP: image plane. b Spectra of the SHG signal obtained by moving the LN slab. c Peak intensity and the total energy of the SHG signal when the sample is moved. The inset shows the details of the peak value near the image plane.