Abstract

Fano resonances are characterized by an efficient ON/OFF amplitude transition in a more reduced wavelength detuning compared with the classical Lorentzian-type resonator of similar quality factors [1]. The sharp asymmetric lineshape with steep slope shown by a Fano resonance would have a considerable advantage for high sensitivity and low detection limit refractive index (RI) sensors [2]. Miniaturized RI sensors based on Si₃N₄ PhC and MRR can realize easy integration and scalability in CMOS fabs. Furthermore, MRR sensors have higher quality factor, relatively simple fabrication, and better stability. In this work, a PhC-MRR resonator structure to realize a Fano-like shape resonance is presented as shown in Fig. 1(a). The MRR is composed by two semi-circular sections with radius R, width W_R and a coupling section L_c matching the number N of lattice periods a included on the PhC. Besides, the PhC is defined by the vertical size W_y, and the type of partial transmitting element (PTE) included: circular (C) or rectangle (S). The coupling distance g_y controls the coupling coefficient between the two resonators.

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