Optical third-harmonic generation (THG) is dipole allowed. I report a 103 signal enhancement of THG that is due to the excitation of a surface plasmon in thin silver films by an attenuated-total-internal-ref lection geometry. Because the THG signal depends on the cube of the incident intensity and the second-harmonic generation depends on the square of the intensity, the THG overtakes the second-harmonic generation at laser intensities beyond 6 × 1011 W/cm2.
© 1996 Optical Society of America
Thomas Y. F. Tsang, "Surface-plasmon-enhanced third-harmonic generation in thin silver films," Opt. Lett. 21, 245-247 (1996)