Tamm plasmons are electromagnetic states located at the interface between a dielectric Bragg mirror and a metal . Contrary to conventional surface plasmons, Tamm plasmons can exist in both TE and TM polarization and its parabolic dispersion lies above the light cone which allow a direct optical excitation at normal incidence. Besides, the Tamm mode confinement can be obtained by simply patterning the thin metallic film, such as microdisks [2,3] or microrectangles . Here, we aim at obtaining ultimate confinement using photonic crystal periodic structures in the metallic layer.
The samples are constituted by a DBR with 4 pairs of l/4n layers of Si and SiO2 above which periodic metallic patterns are defined using e-beam lithography and a 50nm gold deposition. Lift-off is performed at the end of the process. The period of the gratings is chosen to obtain a Tamm Bloch mode around 1.3micrometer.
Microreflectivity experiments show that Tamm Bloch modes exist in such 1D periodic structures. Using an original design, we create a 1D photonic band gap as large as 140nm. Finally, we will present experimental results on cavity-confined Tamm Bloch modes. All results are in good agreement with numerical calculations.
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