Ring Resonator Configuration Research Articles

Triple Micro Optical Multiple Asymmetric Ring Resonator Performance Analysis as Optical Filter

The present article implements the modelling of triple asymmetrical optical micro ring resonator (TAOMRR) in z-domain and the waveguide spacing is designed using Finite Difference Time Domain (FDTD) methodology. The formulation of the transmission function is prepared in z-domain utilizing the delay line signal processing technique. The developed configuration is scrutinized by evaluating the frequency response analysis as well as various important characteristics that are dispersion, group delay, and finesse using MATLAB software. The efficacy of the proposed methodology is tested using OptiFDTD software and it is found that the results of both MATLAB and OptiFDTD are in very nearby settlement. The field analysis of propagated wave inside the microring resonator is shown. The specific gap for various optical directional couplers is also determined using OptiFDTD in this article. The proposed technique is very useful for modeling and analyzing of different configurations of micro optical asymmetric ring resonator which found great application in the field of optical filters as well as optical sensors.

Palm-sized, vibration-insensitive, and vacuum-free all-fiber-photonic module for 10−14-level stabilization of CW lasers and frequency combs

Compact and robust frequency-stabilized laser sources are critical for a variety of fields that require stable frequency standards, including field spectroscopy, radio astronomy, microwave generation, and geophysical monitoring. In this work, we applied a simple and compact fiber ring-resonator configuration that can stabilize both a continuous-wave laser and a self-referenced optical frequency comb to a vibration-insensitive optical fiber delay-line. We could achieve a thermal-noise-limited frequency noise level in the 10 Hz–1 kHz offset frequency range for both the continuous-wave laser and the optical frequency comb with the minimal frequency instability of 2.7 × 10−14 at 0.03-s and 2.6 × 10−14 at 0.01-s averaging time, respectively, under non-vacuum conditions. The optical fiber spool, working as a delay reference, is designed to be insensitive to external vibrations, with a vibration sensitivity of sub-10−10 (1/g) and a volume of 32 ml. Finally, the ring-resonator setup is packaged in a palm-sized aluminum case with 171-ml volume with a vibration-insensitive spool, as well as an even smaller 97-ml-volume case with an ultracompact 9-ml miniaturized fiber spool.

Simulation on continuous-wave silicon carbide Raman laser pumped by 1550 nm lasers

We present a detailed simulation-based analysis of continuous-wave (CW) Raman laser in silicon carbide (SiC) waveguide based on SiC-on-insulator (SiCOI). Both Fabry–Perot (FP) cavity and ring-resonator configurations were designed for Raman lasing, which are pumped by 1550 lasers. According to the Raman coupled wave equation, for FP cavity Raman laser, the relations between laser output performances and key parameters such as output reflectivity, waveguide length, and pump power had been systematically analyzed. Similarly, the effects of ring length, coupling coefficient, and coupler position on the output performance were also investigated based on the ring resonator. The results demonstrate the significant potential of near-infrared Raman lasing from SiC. It provides theoretical guidance for the experimental design of the on-chip SiC Raman laser.

Advancing frequency fine-tuning: a theoretical approach to a novel metamaterial-inspired Bi-layer resonator

This study presents a novel adjustable device designed for precise frequency tuning within the S-band of the microwave spectra. In addition to the geometrical design and dielectric behavior of the resonator, this study identifies an influential governing factor that affects the resonant frequency. The proposed method utilizes a bi-layer split ring resonator configuration implemented on a FR4 epoxy substrate with a dielectric constant of 4.4. The substrate is coated with a 35 μm- thick layer of copper and patterned as split ring resonator. Frequency tuning was achieved by spatially separating the two parallel split ring resonators in increments of 800 μm. This innovative approach allows for a shift in the resonant frequency range from 2.36 GHz to 2.61 GHz, covering the desired frequencies in the S-band for applications such as biomedical and wireless communications. This study demonstrates that the alteration in the frequency domain is dependent on the distance between the two layers of split ring resonators. Compared to existing frequency tuning mechanisms, this adjustable bi-layer split ring resonator offers numerous advantages including simplicity, cost-effectiveness, and high sensitivity. The research employs a combination of finite-element simulations and theoretical analysis to validate the findings.

Design and analysis of ring resonator with slot waveguide coupling into a slab ring construction for refractive index sensing applications

AbstractWe proposed a theoretical study of silicon nitride ring resonator configuration for the application of refractive index sensing. In this paper, a slot waveguide has been used to couple the light into the slab ring structure. We have designed the slab ring and slot waveguides with silicon nitride (Si3N4) on a substrate made of silica (SiO2). Transverse electric (TE) mode has been used for the entire analysis at an operating wavelength of 1550 nm. The presented structure has been geometrically optimized to get the better transmission results. The design shows a resonance wavelength of 1538.74 nm when the cladding refractive index is equal to 1, which is placed at the top of the slab ring structure. We have also calculated the effect on the transmission curve for different waveguide parameters. For, the structure achieves a resonance wavelength around 1563.65 nm. The geometrically optimized structure achieved a Q‐factor of 750 and a sensitivity of 70 nm/RIU. In the proposed paper, the shift in the resonance of the transmission spectrum has been utilized to detect the Refractive Index (RI) changes on the surface of the ring. Therefore, the proposed structure can be used effectively in the applications of refractive index sensing.

Detection of Biomolecules and Glucose Concentration in Blood Using a Subwavelength Grating Optical Biosensor

The research paper describes the design and simulation of an optical biosensor based on a ring resonator with a strip waveguide and a subwavelength grating waveguide. The main goal of the device is to function in low‐loss regions and prevent bending losses in ring resonator configuration. The finite‐difference‐time‐domain analysis is performed to simulate the device and to observe the sensing parameters. The biosensor is intended to be used for sensing biological molecules. The working principle of the sensor is to detect changes in the resonant wavelength caused by changes in the refractive index of biomaterials. By observing the shift in the resonant wavelength, the sensor can provide sensitive and reliable detection of biomolecules in solution. The evaluated sensitivity of the device is 206.3 nm/RIU, with a limit of detection of the order of 10−5 RIU. The device is also tested for the detection of glucose concentration in blood and found to be well‐suited for on‐chip applications. This makes it a promising candidate for use in a wide range of biosensing applications, from medical diagnostics to food safety testing.

Generating Loss Dependent Bifid Dips of Optical Carrier Based Microwave With Self-Feedback Anti-Symmetric Coupled Fiber Ring Resonator

A self-feedback anti-symmetric coupled fiber ring resonator (SACFRR) is proposed and demonstrated to generate the distinctive loss dependent bifid dips. The universal derivation of the ring resonators in both lightwave and optical carrier based microwave domains considering different conditions including attenuation, coupling and self-feedback is systematically elaborated, which is applicable to diverse ring resonator configurations. The lightwave and optical carrier based microwave experience different phase evolution during the cross-coupling procedure, thereby causing very different output. The anti-symmetric coupling strategy is creatively introduced into the ring resonator, which dominates the splitting of the original resonance dip for the optical carrier based microwave interferometry (OCMI). And OCMI shows the noticeable bifid dips within the lower envelope which receives less attention before. By performing the measurement of temperature and bend-induced loss, the bifid dips based demodulation of OCMI is employed to present the property of SACFRR and compared with the conventional upper envelope based demodulation, contributing to the utilization of lower envelope information. The temperature sensitivity is 521.4 kHz/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{\circ }$</tex-math></inline-formula> C at 3.05 GHz and the bend-induced loss sensitivity is 24.845 MHz/turn (diameter of 2.30 cm) at 10 turns where is adjacent to the critical point of bifid dips merging. The proposed scheme provides an extraordinary design avenue which can be extended to diverse ring resonators in both photonic integrated circuits and fiber links for exploring compelling functions.

Demonstration of Coherent Interference between Acoustic Waves Using a Fiber Ring Resonator.

Optical fibers were previously demonstrated to propagate and detect acoustic modes that were converted from Lamb waves for structural health-monitoring applications; typically, a fiber Bragg grating sensor in the optical fiber is used to detect acoustic modes. Acoustic modes can transfer from one fiber to another through a simple adhesive bond coupler, preserving the waveform of the acoustic mode. This paper experimentally investigates the coherence of acoustic waves through the adhesive coupler, using a fiber ring resonator (FRR) configuration. This configuration was chosen because the wave coupled to the second fiber interferes with the original wave after it encircles the fiber ring. We performed this experiment using different geometries of optical fibers in the ring, including a standard single-mode optical fiber, a hollow silica capillary tube, and a large-diameter multi-mode fiber. The results demonstrate that the acoustic wave, when transferring through an adhesive coupler, interferes coherently even when the main and ring fibers are of different types. Finally, we demonstrate that the FRR can be applied for sensing applications by measuring the mode attenuations in the ring due to a changing external environment (water-level sensing) and measuring the optical-path length change in the ring (temperature sensing).

Multiplexed Mach-Zehnder interferometer assisted ring resonator sensor.

A Mach-Zehnder interferometer assisted ring resonator configuration (MARC)-based multiplexed photonic sensor with a large measurement range is experimentally demonstrated. The presented MARC sensor consists of a balanced Mach-Zehnder interferometer and a ring resonator acting as a sensing component. It produces transmission responses with unique spectral signatures, which depend on the physical angular separation between the through port and the drop port waveguides. These unique spectral signatures enhance the effective free spectral range of ring resonators. Hence MARC sensors with a large measurement range are realized. We experimentally demonstrated that the measurement range from the MARC with 135° angular separation is 8x larger than a standard ring resonator. Moreover, by utilizing the MARC, we distinguished the responses from two and three ring resonators multiplexed together. These results verify proof-of-principle for the MARC-based sensors. This inexpensive compact multipurpose device holds promise for numerous applications.

Modelling and Analysis of Quadruple Asymmetrical Optical Micro-Ring Resonator for Biosensing Application

In this paper, modelling of an asymmetrical micro-ring resonator and its performance as an optical filter and optical sensor is analysed. Quadruple asymmetrical optical micro-ring resonator (QAOMRR) is mathematically modelled in Z-domain using delay line signal processing technique. The transmittance of the configuration is calculated using signal flow graph method. Vernier principle method is applied to achieve larger free spectral range (FSR). Also, the proposed QAOMRR in silicon-on-insulator (SOI) platform is used for biochemical sensing. The proposed QAOMRR offers a FSR of 3.155 THZ and Q- factor of 3875 as well as provide significant shift in resonant wavelength whenever any different analyte is present in biomolecules. Field investigation of the proposed QAOMRR is done using Finite Difference Time Domain (FDTD) method. The directional couplers are designed using FDTD simulations. The proposed method will be extremely useful for modelling analysis and design of different micro optical asymmetrical ring resonator configurations.

Fiber based all-optical infinite impulse response filter tuned via stimulated Brillouin scattering

In this paper, we present a novel configuration for an all-fiber tunable infinite impulse response optical filter using stimulated Brillouin scattering. By applying the Brillouin acoustic waves within the coupling area of an optical coupler, we can control its transmissivity and so to affect the spectral response of the IIR optical filter. In this paper, we explain the principle of operation of the proposed device and experimentally demonstrate the ability to control the spectral response of an optical filter based on fiber ring resonator configuration.

Numerical investigation into the output performance of a silicon Raman laser based on a silicon-on-insulator waveguide pumped by 2 µm lasers

We numerically analyze the characteristics of a mid-infrared continuous-wave (CW) Raman laser in silicon-on-insulator (SOI) photonics circuits including standing-cavity and ring resonator configurations, which are pumped by lasers at 2 µm. The dependence of cascaded Raman laser performance on the cavity length, effective free carrier lifetime, and the power transmission is investigated for the optimization of CW Raman silicon standing-cavity lasers. In addition, the mid-infrared Raman laser in the ring resonator is also presented under different parameters; in particular, the coupling strengths between the bus waveguide and the ring resonator for both the pump and Raman lasers are crucial to the laser performance. The numerical simulation results also reveal that the position of the coupler for extracting the Raman light from the ring resonator plays an important role in optimizing the structures of such Raman lasers.

Spectral shaping of ring resonator transmission response.

We present a Mach-Zehnder interferometer assisted ring resonator configuration (MARC) to realize resonator transmission spectra with unique spectral signatures and significantly large effective free spectral ranges. Transmission spectra with unique spectral signatures are generated by changing the angular separation between the through port and the drop port waveguides of the ring resonator (RR). These spectral signatures are comprised of several distinct resonance lineshapes including Lorentzian, inverse Lorentzian and asymmetric Fano-like shapes. One of the spectral signatures generated from the MARC device is utilized for the temperature sensing measurement to demonstrate a MARC-based sensor with high Q-factor and wide measurement range.

Transmission spectra of single ring coupled-waveguide resonator configuration by finite difference time domain method

Development of optical waveguide resonators have greatly expanded and continues to grow since they have kinds potential applications such as wavelength filtering, switching, coupling and multiplexing. One of resonators, coupled waveguides, ring resonators are designed and operated using various coupling configurations. Ring resonators can be particularly used as wavelength filter if the wavelength can fit a whole multiple time in the circumference of the ring. This article proposes to investigate the transmission spectra from the power source and amplify it in linearized ring resonator configurations and varies the input amplitude on five different wavelengths. With finite difference time domain method, the geometry and power source are simulated to obtain the better result and configuration. The results show the intensity phenomena of filtering in optical circuit.

Novel configuration of ultra‐wide band uni‐planar configuration of complementary split ring resonator composite right/left‐handed based band pass filter with sharp roll off and good stopband attenuation

In this paper, a compact novel simple design of ultra-wide bandpass filter with high out of band attenuation is presented. The filter configuration is based on combining an ultra-wide band composite right/left-handed (CRLH) band pass filter (BPF) with simple uni-planar configuration of complementary split ring resonator (UP-CSRR). By integrating two UP-CSRR cells, the ultra-wideband CRLH filter roll-off and wide stopband attenuation are enhanced. The filter has 3 dB cutoff frequencies at 3.1 GHz and 10.6 GHz with insertion loss equals 0.7 dB in average and minimum and maximum values of 0.48 dB and 1.05 dB, respectively over the filter passband. Within the passband. The transition band attenuation from 3 dB to 20 dB is achieved within the frequency band 1.9 GHz to 3.1 GHz (48%) at lower cutoff and the frequency band 10.6 GHz to 11.4 GHz (7%) at upper stopband. Moreover, the filter has a wide stopband attenuation >20 dB in frequencies 11 GHz to 13.6 GHz (21%) and ends with 3 dB cutoff frequency at 14.8 GHz. Furthermore, the designed filter size is very compact (23 × 12 mm2) whose length is only about 0.17 λg at 6.85 GHz. The filter performance is examined using circuit modeling, full-wave simulations, and experimental measurements with good matching between all of them.

Nanodots decorated asymmetric metal–insulator–metal waveguide resonator structure based on Fano resonances for refractive index sensing application

The optical sensors are widely used in biological, chemical and food processing industries for refractive index measurement. A novel metal–insulator–metal square ring resonator configuration is introduced where a nano-slit is diagonally positioned on two opposite sides of the square ring and cavity is decorated with a set of silver nanodots. The resonator’s spectral properties are thoroughly studied by varying the geometric parameters using the finite element method. The sensitivity of the proposed design is improved by regularly positioning the array of nanodots in the cavity where the concentration of E-field is high, as a result, the surface plasmon polaritons (SPPs) are intensified at the boundaries of the dots which enhances the interaction between SPPs and the ambient medium. The device sensitivity can be improved by increasing the size of the nanodots. The maximum sensitivity offered by standard square ring resonator is 1520 nm RIU−1 while the maximum sensitivity of up to 2464 nm RIU−1 can be achieved by adding 16 nanodots of 10 nm radius in two long sides of the cavity in the standard ring resonator. We believe that our findings are useful for the compact and highly sensitive sensor designs and may further enhance the integration level of the integrated optical circuits.

Modeling and performance analysis of single fiber ring incorporated with fiber Bragg grating

The mathematical model of an optical ring resonator (RR) configuration using a single directional optical coupler (DOC) with a uniform fiber Bragg grating (FBG) incorporated and an RR configuration using two DOCs with an FBG incorporated is developed in the Z-domain. The developed mathematical model is used for the evaluation of transmission response. Spectral characteristics in terms of peak transmittance, resonant frequency, and free spectral range are determined for a single fiber ring configuration using two DOCs with an FBG incorporated. The results are found to be in very close agreement with measured values. The transmission characteristic of the single waveguide structure comprising a ring of length 2 mm enclosing a Bragg grating is analyzed. By properly optimizing the grating reflectivity and power coupling ratios of the coupler, a narrow full width at half maximum of 4.72 GHz that is around 78 times sharper than the normal FBG resonance is obtained. Further narrowing of the spectral width is achieved by increasing the RR length. The grating lengths are chosen judiciously to minimize the side peaks. The group delay and dispersion characteristics are addressed.

Advanced realization and characterization of directed optical logic gates using electroabsorptive quantum-well-based micro ring resonator

We propose the implementation of directed logic gates using electroabsorptive (EA) quantum-well (QW) based p-i-n diodes embedded in the waveguiding regions of optical microring resonators (MRR). The absorption of the QW incorporated in the MRR configurations varies with respect to the applied field due to the quantum confined stark effect and results in optical switching by shifting the resonant wavelength. The optical logic gates are realized by representing the operands as the applied field on the rings while the operation results of logic gates appears as in the form of light intensities at the output ports of MRR. The proposed configurations are optimized (in terms of coupling coefficient, operating wavelength and applied field) to acheive logic operations such as AND, NAND, XOR, XNOR and Fredkin gates. EA modulation mechanism fails to implement OR and NOR gates on a parallel MRR configuration due to significant Q-factor reduction as the absorption increases with applied field. A novel electroabsorptive triple ring resonator configuration is proposed which can simultaneously realize optical OR as well as AND gate at the output ports.

Novel single-frequency Nd:YAG ring laser by reducing the depolarization loss

A principle study on reducing the depolarization loss in a single-frequency Nd:YAG ring laser by a novel ring resonator configuration is reported. In the resonator, one cavity mirror with 99.5% reflectivity at 1064 nm for 45-degree incident s-polarized light and about 75% transmissivity for 45-degree incident p-polarized light was employed. Besides, the transmissivity for the 45-degree incident p-polarized and s-polarized light for the output-couple mirror were 32% and 3.5%, respectively. The cavity mirror and the output-couple mirror were utilized as the polarizer to enforce the s-polarized beam unidirectionally operating in the resonator. 2.1 W single-frequency output at 1064 nm with elliptical polarization was obtained from this ring resonator. Compare with the existent Nd:YAG ring resonator, this novel resonator has a potential advantage in reducing depolarization loss and increasing the efficiency.

An array of nano-dots loaded MIM square ring resonator with enhanced sensitivity at NIR wavelength range

A novel configuration of MIM square ring resonator loaded with an array of silver nano-dots is proposed and investigated using the finite element method. The spectral characteristics of the resonator are studied in detail by varying the geometric parameters and material of the inner space of the ring. The sensitivity of the proposed design is enhanced by arranging the array of nano-dots periodically in the cavity which forms a grating and intensifies the SPPs at the boundaries of the dots. As a result, the interaction between SPPs and the surrounding medium is enhanced. The sensitivity of the device can be improved by increasing the number and size of the nano-dots. The maximum sensitivity of standard square ring resonator is 930 nm/RIU. Whereas our proposed design containing 21 nano-dots of 3 nm radius on each side of the cavity can offer a maximum sensitivity up to 1240 nm/RIU. Moreover, our proposed sensor design has FOM and Q-factor of 20 and 20.9 which is better than the standard square ring resonator, respectively. We believe that our findings are valuable for the compact and high sensitive sensors and may advance the integration level of the integrated optical circuits.