Electromagnetically induced absorption in detuned stub waveguides: a simple analytical and experimental model

Abstract

We give an analytical and experimental demonstration of a classical analogue of the electromagnetic induced absorption (EIA) in a simple photonic device consisting of two stubs of lengths d1 and d2 grafted at the same site along a waveguide. By detuning the lengths of the two stubs (i.e. δ = d(2) - d(1)) we show that: (i) the amplitudes of the electromagnetic waves in the two stubs can be written following the two resonators model where each stub plays the role of a radiative resonator with low Q factor. The destructive interference between the waves in the two stubs may give rise to a sharp resonance peak with high Q factor in the transmission as well as in the absorption. (ii) The transmission coefficient around the resonance induced by the stubs can be written following a Fano-like form. In particular, we give an explicit expression of the position, width and Fano parameter of the resonances as a function of δ. (iii) By taking into account the loss in the waveguides, we show that at the transmission resonance, the transmission (reflection) increases (decreases) as a function of δ. Whereas the absorption goes through a maximum around 0.5 for a threshold value δth which depends on the attenuation in the system and then falls to zero. (iv) We give a comparison between the phase of the determinant of the scattering matrix, the so-called Friedel phase and the phase of the transmission amplitude. (v) The effect of the boundary conditions at the end of the resonators on the EIA resonance is also discussed. The analytical results are obtained by means of the Green's function method, whereas the experiments are carried out using coaxial cables in the radio-frequency regime. These results should have important consequences for designing integrated devices such as narrow-frequency optical or microwave filters and high-speed switches.

High Quality Factor Microwave Multichannel Filter Based on Multi-Defectives Resonators Inserted in Periodic Star Waveguides Structure

“…The principal advantage of the electromagnetic SWGs structure presented in this paper is linked to the existence of several transmission peaks of the defects modes depending on the different resonators defects lengths, their numbers, and their positions. The obtained results demonstrate that our proposed filter based on multi-defects modes has a very important transmission coefficient and very high quality factor compared to no-periodic acoustic or photonic waveguides structure system [33,34]. We believe that this paper brings a new piece of work in the field of electromagnetic wave transport in 1D waveguide structures containing different types of metamaterials [35][36][37][38][39][40].…”

Control of acoustic absorption in one-dimensional scattering by resonant scatterers

“…14 Hz is the decay rate due to losses of the HRs [23]. Ignoring the losses, it has been shown that, for small values of the detuning parameter, the transmission coefficient presents an EIT-like mode with unity transmission at f 0 = (f HR 2 +f HR 1 )/2 [2,5,9,24,25]. The lossless transmission coefficient in the complex frequency plane is displayed in Fig.…”

Design of acoustic metamaterials made of Helmholtz resonators for perfect absorption by using the complex frequency plane

“…In this section we review the main features of PA through the interplay of the inherent losses and transparent modes [67][68][69][70][71] with high Q factor as shown in [42]. These modes are generated in a two-port one-dimensional waveguide which is side-loaded by isolated resonators with moderate Q factor.…”