Figure 2
(a) Transmission (solid lines) and reflection (dashed lines) on a logarithmic scale as a function of frequency detuning with different deviation δ. (b) Enlarged version corresponding to the region represented by the dashed box in (a). Even a modest δ = 0.1τ (or about 20% of the loss of individual resonators) can result in a −50 dB minimum transmission. For non-zero δ, the all-pass filter condition is broken due to the difference of the resonators, resulting in non-zero reflection. On the contrary, when the loss coefficients are significantly far from the perfect absorption conditions, such as when τL1 = τL2 = τ (orange line), the maximum absorption is much less profound. It is noteworthy that in such case, since τL1 = τL2, the reflection coefficient is zero, and not shown in the figure.
