Microring Resonator Structure Research Articles

Whispering-Gallery Mode Micro-Ring Resonator Integrated with a Single-Core Fiber Tip for Refractive Index Sensing

A micro-ring resonator structure was fabricated via the two-photon polymerization technique directly on a single-mode fiber tip and tested for refractive index sensing application. The micro-ring structure was used to excite whispering-gallery modes, and observations of the changes in the resonance spectrum introduced by changes in the refractive index of the environment served as the sensing principle. The proposed structure has the advantages of a very simple design, allowing for measurements in reflection mode, relatively easy and fast fabrication and integration with a single tip of a standard single-mode fiber, which allowed for quick and convenient measurements in the optical setup. The performance of the structure was characterized, and the resonant spectrum giving high potential for refractive index sensing was measured. Future perspectives of the research are addressed.

Compact and High-Speed All-Optical 2n:1 Multiplexer Scheme Using MRRs

The purpose of this research paper is to present a new all-optical scheme to implement the logical behavior of generalized [Formula: see text]th-order (2[Formula: see text]:1) multiplexer logic. The proposed all-optical design is based on micro-ring resonator (MRR)-based all-optical switches and constructed by using “2[Formula: see text]-2” MRR structures, arranged in a series “[Formula: see text]” stage architecture. The presented configuration enjoys advantageous features like compact-sized systematic structure and ultra-fast speed. To validate the logical behavior of the proposed [Formula: see text]th-order multiplexer, a second-order (22:1) multiplexer is derived (from the proposed scheme) and discussed. Further, the usability of the presented all-optical multiplexer is demonstrated by developing an all-optical reconfigurable logic gate that can be reconfigured to perform various logic operations. To verify the logical behavior of MRR-based all-optical switch and presented all-optical multiplexer logic, numerical simulations through MATLAB software have been performed. The reported reconfigurable logic structure is also simulated in the MATLAB environment to validate the desired behavior.

Sidewall grating slot waveguide microring resonator biochemical sensor.

Integrated microring resonator structures based on silicon-on-insulator (SOI) platforms are promising candidates for high-performance on-chip sensing. In this work, a novel sidewall grating slot microring resonator (SG-SMRR) with a compact size (5 µm center radius) based on the SOI platform is proposed and demonstrated experimentally. The experiment results show that the refractive index (RI) sensitivity and the limit of detection value are 620 nm/RIU and 1.4 × 10-4 RIU, respectively. The concentration sensitivity and minimum concentration detection limit are 1120 pm/% and 0.05%, respectively. Moreover, the sidewall grating structure makes this sensor free of free spectral range (FSR) limitation. The detection range is significantly enlarged to 84.5 nm in lab measurement, four times that of the FSR of conventional SMRRs. The measured Q-factor is 3.1 × 103, and the straight slot waveguide transmission loss is 24.2 dB/cm under sensing conditions. These results combined with the small form factor associated with a silicon photonics sensor open up applications where high sensitivity and large measurement range are essential.

High-sensitivity electrocardiogram sensor based on Fano resonance in a double-stub-assisted plasmonic micro-ring resonator

Detecting Electrocardiogram (ECG) signals remains a challenge due to its low signal amplitude and low frequency characteristic. In this paper, we suggest a solution to ECG sensor based on Fano resonance of surface plasma wave (SPW) in a Double-Stub-Assisted plasmonic micro-ring resonator (DS-PMRR) structure by exploiting the electro-optic (EO) effect of EO polymer. A theoretical model of Fano resonance of SPW in DS-PMRR is established to analyze the sensitivity of ECG sensor. A moderately symmetrical cone mode converter is designed to achieve the efficient coupling between silicon on insulator (SOI) waveguide and metal–insulator–metal (MIM) waveguide. The whole structure with an active zone as small as 5 μm × 8.4 μm × 0.2 μm is analyzed by finite-element method (FEM) and a sensitivity of 11740 pm/V is obtained. In combination with a sub-picometer optical spectrum analyzer, the proposed sensor can detect ECG signals with the magnitude on the order of 10 μv.

On chip optical neural networks based on MMI microring resonators for image classification

We propose a new on-chip optical neural network (OONN) based on multimode interference-microring resonators (MMI-RRs). The suggested structure eliminates the need for wavelength division multiplexers (WDM) to create an optical neuron on a single chip. New microring resonator structure based on 4×4 MMI coupler with a size of 24µm × 2900 µm is used for the basic elements of the computation matrix, as a result a higher bandwidth and free spectral range (FSR) can be achieved. The Si3N4 platform along with the graphene sheet is designed to modulate the signals and weights of the neural networks at a very high speed. The Si3N4 can provide wide range of operating wavelengths and can work directly with the wavelengths of color images. The structure's benefits include rapid computing speed, little loss, and the ability to handle both positive and negative values. The OONN has been applied to the MNIST dataset with a speed faster than 2.8 to 14x times compared with the conventional GPU methods.

Thermo-optic phase shifter based on amorphous silicon carbide

We report the preliminary experimental results for an amorphous silicon carbide (a-SiC) thermo-optic phase shifter (TOPS). This device is based on microring resonator (MRR) structure with a titanium (Ti) heater placed on the top of the device, separated by 1.5 μm thick SiO2 to reduce the optical loss. The proposed a-SiC microring has a thickness and a radius of 1.1 μm and 33 μm, respectively. By applying an electrical power in the Ti heater, a resonance wavelength shift at an optical wavelength of λ=1550 nm is shown, and the extracted thermal tunability is 52.2 pm/mW.

Racetrack microring resonator with improved quality factor based on asymmetric waveguide bend

Racetrack microring resonators with improved quality factors based on asymmetric Bezier waveguide bend for silicon nitride photonics integration platform have been proposed and demonstrated experimentally in this paper. The asymmetric Bezier waveguide bend can reduce bend loss which is one of the major limitations of the Q factor of racetrack microring resonators. The proposed racetrack microring resonator structure based on an asymmetric Bezier bend waveguide can significantly improve the Q factor while maintaining the same device area. Such racetrack microring resonators with superior performance can help improve the performance of on-chip devices and further promote the development of a photonic integration platform.

Sensing performance of temperature insensitive microring resonators with double-layer U-shaped waveguide

An temperature insensitive microring resonator with double-layer U-shaped waveguide for sensing applications is proposed and investigated theoretically. The unique structure of microring resonator with double-layer U-shaped waveguide not only limits the light field in the ring, but also releases the evanescent field from the waveguide through the coupling of the upper and lower layers, thus enhancing the interaction between light and matter and improving the sensing ability. Then, through correctly selecting the cross-sectional dimensions of the waveguide, the bending radius, the spacing between the upper and lower waveguides and the shape of overlapping area, it is designed to have very low temperature dependence in aqueous solution, so as to obtain sensing accuracy and stability. The simulation results show that the sensitivity is 496 nm/RIU ± 5 pm/K. Within the temperature change range of 3.2 K, it can be considered that the measurement result is irrelevant to the change in ambient temperature. Compared with the other ring resonators, this resonator does not need extra temperature compensation equipment, active temperature controller, polymer cladding, or even extra processing of the measured data to eliminate the effect of temperature. Thanks to its excellent performance in temperature insensitive and sensing performance, the device is suitable for refractive index measurement in a complex environment. It might have broad application prospects in portable real-time monitoring equipment, for example, analyzing health status from the change of sweat composition, or detecting the content of microorganisms and other harmful substances in drinking water.

Design and analysis of all-optical nibble multiplexer with tri-stated outputs using micro-ring resonator structure

Design and analysis of all-optical nibble multiplexer with tri-stated outputs using micro-ring resonator structure

Design and Analysis of All Optical Sequence Detector Using Micro-ring Resonator Structures

Design and Analysis of All Optical Sequence Detector Using Micro-ring Resonator Structures

Controlling Microring Resonator Extinction Ratio via Metal‐Halide Perovskite Nonlinearity

AbstractThe exceptionally high optical nonlinearities, wide bandgap, and homogeneity in solution‐processed metal‐halide perovskite media are utilized as optical nonlinear elements on a silicon photonic platform for low‐power‐active components, such as all‐optical switches, modulators, and lasers. With room temperature back‐end‐of‐line compatible processing, a hybrid metal‐halide perovskite (CH3NH3PbI3) microring resonator (MRR) structure is fabricated on a foundry‐processed low‐loss silicon photonic platform. With in‐plane excitation near the light intensity of 110 W m−2, strong two‐photon absorption and free‐carrier absorption saturation are observed. With 103 field enhancements by MRRs, the photorefractive effect in the metal‐halide perovskite reduces linear absorption, represented by 102 improvement of the MRR's intrinsic quality factor and 20 dB enhancement of the extinction ratio.

Implementation of all-optical 1 × 4 memory register unit using the micro-ring resonator structures

Implementation of switching activity in the all-optical domain is an essential aspect of modern high-speed and secured communication technology. Micro-ring Resonator (MRR) based switching activity can be used to implement all-optical active low tri-state buffer logic and clocked D flip-flop. The paper describes the switching activity of micro-ring resonator structures. The switching activity is further used to implement the effective all-optical 4-bit memory register using the appropriate arrangement of all-optical tri-state buffers and clocked D flip-flops with the functionality of read (RD) and write (WR). The complete description of layouts and switching mechanisms of all-optical 4-bit memory registers have been explained, and appropriate MATLAB simulation results are presented to observe the suitability of the proposed unit. The analysis shows that implementation of tri-state buffer logic and D flip-flop assisted 4-bit memory register in the all-optical domain includes the considerable advantages of optical communication, e.g., immunity to electromagnetic interference, parallel computing, compactness, signal security, etc. The manuscript describes the detailed analysis of performance parameters, e.g., extinction ratio, contrast ratio, amplitude modulation, on–off ratio, and switching speed of micro-ring resonator structures to efficiently select device parameters. Finally, it describes an efficient technique to implement all-optical MRR based $$1\times 4$$ 1 × 4 memory registers.

Design of ultra-compact TE mode ring optical isolator using a cobalt ferrite film for silicon photonic integrated circuits

In this study, we present the design of an integrated transverse electric mode isolator realized by the epitaxial growth of a cobalt ferrite (CFO) film on a silicon micro-ring resonator structure. Exploiting the large magneto-optical activity of CFO along with the good characteristics of resonator structures, we numerically demonstrated isolator designs with ultra-compact sizes. The use of ring resonator structures with the reduced size is appealing because of lower insertion loss values. The nonreciprocal phase shift was maximized by optimizing the ring cross-section and was further studied in terms of the ring radius employing a transformation optics theory. Finally, we analyzed the optical isolator characteristics in terms of ring size and ring-waveguide power coupling ratio. The computed results pointed out that decreasing the ring size improves the device performance and can ease the device design and fabrication process.

Simulation and Analysis of Microring Electric Field Sensor Based on a Lithium Niobate-on-Insulator

With the increasing sensitivity and accuracy of contemporary high-performance electronic information systems to electromagnetic energy, they are also very vulnerable to be damaged by high-energy electromagnetic fields. In this work, an all-dielectric electromagnetic field sensor is proposed based on a microring resonator structure. The sensor is designed to work at 35 GHz RF field using a lithium niobate-on-insulator (LNOI) material system. The 2.5-D variational finite difference time domain (varFDTD) and finite difference eigenmode (FDE) methods are utilized to analyze the single-mode condition, bending loss, as well as the transmission loss to achieve optimized waveguide dimensions. In order to obtain higher sensitivity, the quality factor (Q-factor) of the microring resonator is optimized to be 106 with the total ring circumference of 3766.59 μm. The lithium niobate layer is adopted in z-cut direction to utilize TM mode in the proposed all-dielectric electric field sensor, and with the help of the periodically poled lithium niobate (PPLN) technology, the electro-optic (EO) tunability of the device is enhanced to 48 pm·μm/V.

Implementation of all-optical ripple down counter using the micro-ring resonator structures

Micro-ring resonator (MRR)-based switching is one of the promising technologies in modern optical signal processing and optical computing. In this paper, we present a scheme of all-optical 2-bit ripple down counter, using the MRR-based all-optical switching activity. The proposed mechanism shows the generation of all-optical two bits ripple down sequences without any involvement of electrical pumping. The optical pumping shows one of the innovative ways to overcome the complexity associated with electrical pumping. The paper includes the detailed mathematical analysis of all-optical switches in the form of a micro-ring resonator structure. We proposed four cascaded micro-ring resonator structures representing all-optical ripple down counters, and numerical simulation is presented with some additional analysis. The proposed design is simple and may be helpful for all-optical signal processing and logical computation.Author names: Please confirm if the author names are presented accurately and in the correct sequence (given name, middle name/initial, family name). Given name: [Sumit Kumar] Last name [Jindal]. Also, kindly confirm the details in the metadata are correct.It is OKAuthor details: Kindly check and confirm whether the corresponding author and mail ID are correctly identified.ok

On the Ring Resonator-Based Dispersion Compensation Method for Analog 5G/B5G Mobile Fronthauling

We present a novel technique for dispersion compensation by exploiting the filtering properties of a fully reconfigurable serially coupled microring resonator (MRR) structure in analog intermediate frequency-over-fiber/mmWave (IFoF/mmWave) fiber/wireless 5G and beyond 5G(B5G)-oriented mobile fronthaul. To this extend, we demonstrate simulation and experimental results on analog photonic processing of 1 Gbaud quadrature phase shift keying (QPSK) modulated radio signal. By tuning filter's bandwidth in the range of 14–69 GHz, and resonance within a resonance free spectral range (FSR) range, dispersion induced power fading mitigation was achieved, for a set of widely adopted intermediate frequencies (IFs) and transmission distances. Analytical calculations carried out in MATLAB environment, highlighting significant improvement of transmission system output power, whereas are verified via transmission system simulations, resulting to error vector magnitude (EVM) improvement up to ∼ 30%. Experimental results verified both analytical and transmission simulation results for a series of IFoF downlink transmission system configurations. For widely used wireless transmission configuration at 8.5 GHz IF, by tuning the filter to appropriate bandwidth of 14 GHz and resonance peak properly, successful fiber wireless transmission for over 25 km of fiber was demonstrated, achieving 16.9% EVM for QPSK, below the 3GPP (<17.5%) requirements for 5G NR.

Reflective-Type Microring Resonator for On-Chip Reconfigurable Microwave Photonic Systems

Microring resonator (MRR) is regarded as one of the most widely-used building blocks in photonic integration, which is employed to implement optical filtering, routing, sensing, true time delay, signal processing, logic operations and so on. However, a single MRR intrinsically produces Lorentzian or Lorentzian-derivative shape responses with very sharp peaks, which is incapable of handling wideband signals for microwave photonic systems. In this paper, we introduce a reflective-type MRR with a reflector connected to the drop port of an add-drop MRR. Thanks to the reflector, reconfigurable intensity and group delay responses can be achieved by setting the coupling coefficients of the MRR, leading to the implementation of flat-top filtering, wideband optical true time delay, XNOR/XOR optical logic operation and electro-optic modulation. Both theoretical analysis and experimental demonstration are carried out. This new MRR structure may enable a new, compact and low-cost design strategy for the integrated reconfigurable or programmable microwave photonic systems.

Subwavelength hole defect assisted microring resonator for a compact rectangular filter.

We propose and demonstrate a subwavelength hole defect assisted microring resonator (SHDAMR) structure. With the manipulated modal coupling between two degenerate counterpropagating modes induced by a subwavelength hole defect embedded in the microring waveguide, the SHDAMR structure shows a rectangular resonance lineshape instead of the Lorentzian resonance lineshape of a conventional microring. As a proof of concept, the SHDAMR structure is fabricated on the Si3N4 waveguide platform, for achieving a rectangular filter with a 3-dB bandwidth of 2.03 GHz and an improved shape factor. The demonstrated SHDAMR structure shows the advantages of compact footprint, simplified tunability, and large tolerance of fabrication errors, showing great potential for various applications.

Design of an Ultra-Compact and Highly-Sensitive Temperature Sensor Using Photonic Crystal Based Single Micro-Ring Resonator and Cascaded Micro-Ring Resonator

In the present report, a photonic crystal based micro-ring resonator (MRR) structure is proposed which is very compact in size and has very fast response and is employed for temperature sensing purpose. Temperature sensing application for both the single MRR and cascaded MRR is illustrated in this paper. The sensitivity of the reported structure is increased from 2.9 nm/°C to 3.4 nm/°C by cascading two MRR. The refractive index of the material is subjected to change with the variation in temperature which results in the shift of the resonant wavelength of the proposed sensor. The finite difference time domain (FDTD) simulation is utilized to see the transmission spectrum of the proposed structure and analyzing the shift in the resonance wavelength the temperature is calculated. The proposed design is simple, reliable and may be integrated into different transducer and sensing applications.

Silicon sub-wavelength grating resonator structures for gas sensor

Abstract This study investigates the use of silicon material as an optical waveguide for a subwavelength grating (SWG) design and micro-ring resonator structure under different conditions with CO2 as upper cladding. The CO2 was chosen to measure the sensitivity of the optical waveguide sensor, as it has a refractive index similar to air. The highest Qfactor was achieved (96.87) in the throughput port when CO2 was used as Bragg grating. The CO2 as upper cladding had a 0.4 fs time delay, considering the air as a reference spectrum. The time delay that is measured can be used to achieve higher material sensitivity. Frequency in the THz range was successfully achieved using the proposed optical waveguide sensor design and structure.