Synthesis of high-order bandpass filters based on coupled-resonator optical waveguides (CROWs)

Liu, Hsi-Chun; Yariv, Amnon

doi:10.1364/oe.19.017653

Cited by 71 publications

(45 citation statements)

References 26 publications

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“…By further decreasing t 2 , the Q factor, extinction ratio, and group delay of the combined single resonance increases, together with an increase in the insertion loss. In particular, when t 2 = 0.77, a band-pass Butterworth filter 34 with a flat-top filter shape can be realized, which is desirable for signal filtering in optical communications systems. 35,36 On the other hand, when t 2 = 0.742, the CSLR resonator exhibits a flat-top group delay spectrum, which can be used as a Bessel filter for optical buffering.…”

Section: Device Configuration and Operation Principlementioning

confidence: 99%

Advanced photonic filters based on cascaded Sagnac loop reflector resonators in silicon-on-insulator nanowires

et al. 2018

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We demonstrate advanced integrated photonic filters in silicon-on-insulator (SOI) nanowires implemented by cascaded Sagnac loop reflector (CSLR) resonators. We investigate mode splitting in these standing-wave (SW) resonators and demonstrate its use for engineering the spectral profile of on-chip photonic filters. By changing the reflectivity of the Sagnac loop reflectors (SLRs) and the phase shifts along the connecting waveguides, we tailor mode splitting in the CSLR resonators to achieve a wide range of filter shapes for diverse applications including enhanced light trapping, flat-top filtering, Q factor enhancement, and signal reshaping. We present the theoretical designs and compare the CSLR resonators with three, four, and eight SLRs fabricated in SOI. We achieve versatile filter shapes in the measured transmission spectra via diverse mode splitting that agree well with theory. This work confirms the effectiveness of using CSLR resonators as integrated multi-functional SW filters for flexible spectral engineering.

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Section: Device Configuration and Operation Principlementioning

confidence: 99%

Advanced photonic filters based on cascaded Sagnac loop reflector resonators in silicon-on-insulator nanowires

et al. 2018

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“…with the assumption of exp(−κ g L) ≪ 1 [9,18]. The group velocity at resonant frequency is thus , 2 2 exp( )…”

Section: Coupled-mode Formalism For Grating Crowsmentioning

confidence: 99%

“…We choose a group index of 4 and a weak grating with κ g = 0.01/µm. The lengths of the first and last grating sections, L 1 and L N + 1 , are chosen to be L/2 to match the CROW section to the waveguides [18]. According to Eq.…”

Section: Coupled-mode Formalism For Grating Crowsmentioning

confidence: 99%

“…For the first or last resonators, the external loss rate to the waveguides is given by (also shown in the appendix) where n reg is the number of regular holes in the first or last grating section. To match between the CROW and the waveguides, we require κ = 1/τ e [18]. Therefore, the number of holes in the first and last sections is one half of the number of holes in the middle sections, i.e.…”

Section: Crows Based On Tapered Grating-defect Resonatorsmentioning

confidence: 99%

“…For example, Butterworth filters exhibit maximally flat transmission, while Bessel filters possess maximally flat group delay. For a desired filter response, the coupling coefficients which determine the transfer function of CROWs can be derived [18,20]. Table 1 lists the coupling coefficients of N = 10 Butterworth and Bessel filters respectively.…”

Section: Filter Design Based On Grating Crowsmentioning

confidence: 99%

See 2 more Smart Citations

Designing coupled-resonator optical waveguides based on high-Q tapered grating-defect resonators

Liu

Yariv

2012

Opt. Express

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Abstract:We present a systematic design of coupled-resonator optical waveguides (CROWs) based on high-Q tapered grating-defect resonators. The formalism is based on coupled-mode theory where forward and backward waveguide modes are coupled by the grating. Although applied to strong gratings (periodic air holes in single-mode silicon-on-insulator waveguides), coupled-mode theory is shown to be valid, since the spatial Fourier transform of the resonant mode is engineered to minimize the coupling to radiation modes and thus the propagation loss. We demonstrate the numerical characterization of strong gratings, the design of high-Q tapered grating-defect resonators (Q>2 × 10 6 , modal volume = 0.38·(λ/n) 3 ), and the control of inter-resonator coupling for CROWs. Furthermore, we design Butterworth and Bessel filters by tailoring the numbers of holes between adjacent defects. We show with numerical simulation that Butterworth CROWs are more tolerant against fabrication disorder than CROWs with uniform coupling coefficient.

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All‐Bands‐Flat Floquet Topological Photonic Insulators with Microring Lattices

Song,

Van

2024

Advanced Photonics Research

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Coupled microring lattices are versatile photonic systems that can be used to realize various topological phases of matter. In two‐dimensional (2D) microring lattices, the periodic and unidirectional circulation of light in each microring gives rise to a time‐like dimension, so that the lattice emulates a (2 + 1)D system with much richer topological behaviors than static 2D lattices. Accurate treatment of these systems requires a departure from the static tight‐binding model of coupled resonators and take into account the periodic coupling sequence of light in the lattice network. This article provides an overview of the theory and design of (2 + 1)D microring lattices for realizing Floquet topological photonic insulators (TPIs). Particular focus is placed on the microring Lieb lattice with perfect couplings, which emulates an anomalous Floquet insulator with all flat bands. Such a system exhibits some unique properties, including wide edge mode continuum exceeding a Floquet–Brillouin zone, super‐robustness to lattice disorder, Aharonov–Bohm (AB) caging and compact localized flat‐band states that can be used to realize high‐quality factor topological resonators. All‐bands‐flat Floquet–Lieb microring lattices provide a versatile platform for investigating topological physics as well as potential applications in realizing topologically‐protected photonic devices.

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Synthesis of high-order bandpass filters based on coupled-resonator optical waveguides (CROWs)

Cited by 71 publications

References 26 publications

Advanced photonic filters based on cascaded Sagnac loop reflector resonators in silicon-on-insulator nanowires

Advanced photonic filters based on cascaded Sagnac loop reflector resonators in silicon-on-insulator nanowires

Designing coupled-resonator optical waveguides based on high-Q tapered grating-defect resonators

All‐Bands‐Flat Floquet Topological Photonic Insulators with Microring Lattices

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