Nested ring Mach-Zehnder interferometer

Abstract

We propose a new device configuration that incorporates a nested ring with a Mach-Zehnder interferometer. The nested ring is analogous to a dual-bus coupled ring resonator, with the ends of the two buses connected to form a semi-closed loop. With proper design of the length of the U-shaped loop, as well as the coupling coefficient between the ring and the waveguide, the device is capable of generating a box-shaped spectral response. This is shown to be mainly due to the double-Fano resonances that arise from constructive interference between the nested ring and the outer loop. The device is simple in that it requires only one ring, and unique in that it harnesses a pair of Fano resonances to generate a reasonably box-like filter response. The analysis is based on the transfer matrix formalism, and compared and verified with the FDTD simulations.

Analysis on transmission characteristics of nested ring resonators

“…Different structures have different transmission properties and can be used to satisfy various applications, such as filtering [8,9], sensing [10,11], and group velocity control [12,13]. Darmawan et al once proposed a novel configuration named as nested ring resonator (NRR) and used it in a Mach-Zehnder interferometer to generate a boxshaped spectral response [14,15]. The NRR is constructed with a dual-bus ring by connecting the two buses to a U-shaped waveguide.…”

“…For example, when the length of the U-shaped loop is an integer multiple of the inner circle ring, the free spectral range (FSR) will be doubled compared with common singlering resonators of the same size [16]. In addition, it supports coupled-resonator-induced transparency (CRIT), which is impossible for common single-ring structures [14,16]. To know the NRR better, in this paper, more in-depth analysis is applied on its transmission characteristics.…”

Ultrahigh sensing based on feedback double ring configuration beyond the limitation of quality factor on sensitivity

“…Large quantities of these sensing techniques mentioned above are based on optical resonators [10,11]. The root of this configuration is that its transmission exhibits a periodic-notch spectrum, and steep dips appear when the frequency of the input light field is equal to the resonance frequency of the resonator.…”

Mach–Zehnder–Fano interferometer

“…The recent developments moved this concept toward nanoscales, and several studies employed ring-resonator structures in order to low the power threshold [1,2,3,4,5,6,7,8] which can demonstrate very efficient nonlinear response and can be easily tuned. A novel advantage of using additional resonant cavities has been also discussed [9,10,11,12,13].In this Letter we introduce a concept of the MachZehnder-Fano interferometer that can be realized on various platforms such as photonic crystals or ring resonators that possess effective discreteness of periodic photonic structures for engineering the transmission properties. Side-coupled cavity with a resonant state in the transmission band provides a sharp variation of the scattering phase, which allows to alter the transmission properties of the whole structure in a narrow frequency range.…”

“…The recent developments moved this concept toward nanoscales, and several studies employed ring-resonator structures in order to low the power threshold [1,2,3,4,5,6,7,8] which can demonstrate very efficient nonlinear response and can be easily tuned. A novel advantage of using additional resonant cavities has been also discussed [9,10,11,12,13].…”