We present an improved analytical model describing transmittance of a metal-dielectric-metal (MDM) waveguide coupled to an arbitrary number of stubs. The model is built on the well-known analogy between MDM waveguides and microwave transmission lines. This analogy allows one to establish equivalent networks for different MDM-waveguide geometries and to calculate their optical transmission spectra using standard analytical tools of transmission-line theory. A substantial advantage of our model compared to earlier works is that it precisely incorporates the dissipation of surface plasmon polaritons resulting from ohmic losses inside any metal at optical frequencies. We derive analytical expressions for transmittance of MDM waveguides coupled to single and double stubs as well as to N identical stubs with a periodic arrangement. We show that certain phase-matching conditions must be satisfied to provide opt al filtering characteristics for such waveguides. To check the accuracy of our model, its results are compared with numerical data obtained from the full-blown finite-difference time-domain simulations. Close agreement between the two suggests that our analytical model is suitable for rapid design optimization of MDM-waveguide-based compact photonic devices.

Two-dimensional (2-D) compact photonic crystal reflectors on suspended InP membranes were studied under normal incidence. We report the first experimental demonstration of 2-D broadband reflectors (experimental stopband superior to 200 nm, theoretical stopband of 350 nm). They are based on the coupling of free space waves with two slow Bloch modes of the crystal. Moreover, they present a very strong sensitivity of the polarization dependence, when modifying their geometry. A compact (50 50 m 2) demonstrator was realized and characterized, behaving either as a broadband reflector or as a broadband transmitter, depending on the polarization of the incident wave. Experimental results are in good agreement with numerical simulations.

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The exciton–polaritonic states are generated by the strong interaction between photons and excitons in confined nanocavities. To achieve strong coupling between excitons in TMDCs and optical modes in cavities is quite challenging due to fabrication issues, modal and material dispersion in the cavity, and the weak confinement of the optical field. Hence, investigation of new photonic structures to achieve strong coupling in TMDCs materials is necessary to develop polariton-based devices. Here, we report the observation of the strong coupling between an anapole mode in a slotted silicon nanodisk and an exciton in a WSe2 monolayer, leading to the creation of anapole–exciton polaritons. Furthermore, we have also demonstrated a strong anapole–plasmon and anapole–plasmon–exciton coupling in Si–Ag, and Si–Ag–WSe2 heterostructures, respectively. The observed polaritonic hybrid states have a large Rabi splitting (159 meV) accompanied by high localized field enhancement (157 times increase) in the near field and at a normal incident angle, suggesting a crucial step toward the creation of exciton–polariton nanodevices.