We propose and theoretically investigate integrated photonic filters based on two coupled Sagnac loop reflectors (SLRs) formed by a self-coupled optical waveguide. Recently we investigated integrated photonic filters based on cascaded SLRs and coupled SLRs. Here, we advance this field by presenting a unique approach of using coupled SLRs formed by a self-coupled optical waveguide. This enables us to achieve high performance filter functions including Fano-like resonances and wavelength interleaving with a simpler design and a higher fabrication tolerance by tailoring coherent mode interference in the device. Our design takes into account the device fabrication issues as well as the requirements for practical applications. As a guide for practical device fabrication, an analysis of the impact of the structural parameters and fabrication tolerance on each filter function is also provided. The Fano-like resonances show a low insertion loss (IL) of 1.1 dB, a high extinction ratio of 30.2 dB, and a high slope rate (SR) of 747.64 dB/nm. The combination of low IL and high SR promises this device for Fano resonance applications. Our device also can achieve wavelength de-interleaving function with high fabrication tolerance which is attractive for optical interleavers that need a flat-top symmetric filter shape. Optical interleavers and de-interleavers are core elements for signal multiplexing and demultiplexing in wavelength division multiplexing optical communication systems. Versatile spectral responses with a simple design, compact device footprint, and high fabrication tolerance make this approach highly promising for flexible response shaping in a wide variety of applications.
We present theoretical designs of high performance optical filters in integrated silicon photonic nanowire resonators. We use mode interference in formed by zig-zag waveguide coupled Sagnac loop reflectors (ZWC-SLRs), tailored to achieve diverse filtering functions with good performance. These include compact bandpass filters with improved roll-off, optical analogues of Fano resonances with ultrahigh spectral extinction ratios (ERs) and slope rates, and resonance mode splitting with high ERs and low free spectral ranges. The analysis verifies the feasibility of multi-functional integrated photonic filters based on ZWC-SLR resonators for flexible spectral engineering in diverse applications.
Advanced photonic filters implemented by cascaded Sagnac loop reflectors (CSLRs) in silicon-on-insulator (SOI) nanowires are experimentally demonstrated. Based on mode splitting in these standing-wave (SW) resonators, we achieved diverse filtering shapes for spectral engineering showing good agreement with theory.
We have proposed and numerically investigated two plasmonic structures for bandpass and band-stop filters. The bandpass filter is composed of two metal–insulator–metal (MIM) waveguides coupled to each other by a nonlinear rectangular nanocavity. The band-stop filter consists of an MIM waveguide side coupled to a Kerr-type nonlinear rectangular nanocavity. The optical filtering effect is verified by two-dimensional (2-D) finite-difference time-domain (FDTD) simulations. It is demonstrated that based on optical nonlinearity we can easily make the proposed filters tunable by properly adjusting the intensity of incident light without changing the dimensions of the structures. The simulation results revealed that within the transmission spectrum, the selected central wavelength and the bandwidth of the filter can be tuned by the input signal intensity. The proposed structures are suitable to be used as highly dense integrated optical circuits, where limitations on the dimensions of the filter structure are vital.
A nanoscale optical filter based on metal-insulator-metal waveguides and a Kerr-type nonlinear nanoslot resonator is introduced and numerically investigated by finite-difference time-domain simulations. It is demonstrated that the resonant wavelengths of the nanoslot resonator experience a red shift due to the intensity dependence of the Kerr nonlinear effect. The simulation results reveal that the resonant modes of the proposed filter can be tuned by properly adjusting the input signal intensity without changing the dimensions of the filter structure. The findings of this study are useful for highly integrated optical circuits, for which we have limitations on the dimensions of the filter structure. In addition, the results are suitable for design of integrated optical waveguides and resonators based on the plasmonic effect. A significant advantage of the proposed tunable filter is its ease of fabrication.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.