Fig. 2: Experimental geometry.

a Schematic of the microscope configuration used to characterize the second harmonic generation (SHG) response of single particles. This microscope was operated in a reflection mode setup and was equipped with a femtosecond laser, half-wave plate, and objective lenses of different magnifications including a 63× oil immersion lens. b Sketch of the sample geometry of the hybrid Au–LiNbO3 particles