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.

Figure 1

(a) Sketch of the experiment. Transmittance spectrum of type 1 (b) and type 2 (c) samples measured at normal incidence. Shaded areas indicate the regions which are spectrally scanned with the change of the angle of incidence from $0^{\circ }$ to ${60}^{\circ }$.

Figure 2

Angular dependence of normalized efficiency of the second-harmonic generation in type-1 sample (dots), numerical calculations of the SHG efficiency (dotted curve), and transmittance of the fundamental radiation with the wavelength of 1560 nm (red curve).

Figure 3

Normalized THG efficiency in type-2 sample, measured in a $pp$ geometry (dots). The transmittance of a fundamental radiation at the wavelength of 1560 nm (red curve). Inset shows the TH intensity vs fundamental power in log-log scale.

Figure 4

Angular dependence of the normalized THG efficiency in a PC/metal sample in pp-polarization combination. Black diamonds correspond to the case when the PC side of the sample faces the fundamental radiation; red dots correspond to the case when the metal layer faces the fundamental radiation. Inset shows magnitudes of partial contributions of individual layers to the third-harmonic field calculated at ${21}^{\circ }$ angle of incidence for the described orientations of the sample.

Figure 5

Calculated dependence of THG efficiency vs angle of incidence and thickness of the topmost layer of photonic crystal normalized to the thickness of the regular $B*$ layer.