Phase matching with Tamm plasmons for enhanced second- and third-harmonic generation

We demonstrate that the intensity of optical second and third harmonics generated in a one-dimensional photonic crystal--thin metal film sample is greatly enhanced in the presence of Tamm plasmons. The emergence of a localized optical Tamm state means that the local density of photonic states is resonantly enhanced at the interface of photonic crystal and metal within the vicinity of the excitation wavelength. When the fundamental radiation spectrum overlaps with the Tamm mode, the efficiency of the second-harmonic generation was enhanced by two orders of magnitude as compared with a bare metal film. In the case of the off-resonant fundamental radiation and the second-harmonic wavelength overlapping with the Tamm plasmon mode, the conversion efficiency increased by one order of magnitude. The overall intensity of the third-harmonic generation was enhanced by almost five orders of magnitude in the phase-matching conditions. In this case the fundamental radiation resonates with the fundamental Tamm plasmon, while the third-harmonic radiation resonates with the third-order Tamm plasmon.