Classic analogue of Autler–Townes-splitting transparency using a single magneto-optical ring resonator

We show that an optical transparency can be obtained by using only one single magneto-optical ring resonator. This effect is based on the splitting of counterclockwise and clockwise modes in the ring resonator. Within a proposed resonator-waveguide configuration the superposition between the two degeneracy broken modes produces a transparency window,which can be closed, open, and modified by tuning the applied magnetic field. This phenomenon is an analogue of Autler–Townes splitting, and the magnetic field is equivalent to the strong external pump field. We provide a theoretic analysis on the induced transparency, and numerically demonstrate the effect using full-wave simulation. Feasible implication of this effect and its potential applications are also discussed.

Terahertz Transmission Properties of Split Ring Resonator Arrays

The transmission properties of double-ring split ring resonator(SRR) arrays and closed ring resonator arrays are measured using terahertz(THz) time-domain spectroscopy. This technique allows for the simultaneous measurement of the amplitude and phase of the transmission coefficient as a function of frequency. The ability to directly measure the phase spectrum is expected to be important in characterizing potential negative index media. In the employed experimental geometry, THz pulses are normally incident on the arrays. Thus, the magnetic field lies in the plane of the arrays and cannot contribute to the magnetic resonance of the SRR. However, it is found that the electric field, when appropriately polarized, can couple to the magnetic resonance. Shifts in the resonance properties with changes in the SRR dimensions and the substrate medium are measured, the results of which are consistent with theory.

Design and analysis of multi-channel drop filter using dual L defected hexagonal photonic crystal ring resonator

In this paper,dual L defected hexagonal Photonic Crystal Ring Resonator(PCRR)using Channel Drop Filter(CDF)is designed for Coarse Wavelength Division Multiplexing(CWDM)systems.In this structure,the external rods of the ring resonator are arranged in a hexagon and the internal rods are removed in L arrangement for introducing defects.Scatter rods are used to prevent leakage.By using the L defected hexagonal resonator,a multi-channel CDF is designed,which exhibits multiple wavelengths of CWDM(1500 nm–1600 nm)region.In addition,the selection of rod size and the position of rods in the proposed multi-channel CDF are validated by varying the radius of coupling and scattering rods,as well as the position of resonators,respectively.By using plane wave expansion and opti Finite Difference Time Domain(FDTD)method,the electromagnetic wave propagation and the photonic band gap are obtained.

Electric and magnetic dipole couplings in split ring resonator metamaterials

In this paper, the electric and the magnetic dipole couplings between the outer and the inner rings of a single split ring resonator （SRR） are investigated. We numerically demonstrate that the magnetic resonance frequency can be substantially modified by changing the couplings of the electric and magnetic dipoles, and give a theoretical expression of the magnetic resonance frequency. The results in this work are expected to be conducive to a deeper understanding of the SRR and other similar metamaterials, and provide new guidance for complex metamaterials design with a tailored electromagnetic response.

Miniaturized multi-band antenna using deformed splot ring resonator

A 48 mm x 60 mm x 1 mm miniaturized multi band antenna based on deformed split ring re sonators was presented. The antenna was consisted of a micro strip line and a deformed split square ring. Its/S11/parameters were determined through numerical simulation and experimental measure ment within three working bands of 2.6 GHz to 3. 0 GHz, 3. 9 GHz to 4. 4 GHz and 5.2 GHz to 5. 8 GHz and the results showed that the parameters within all the bands were less than 10 dB. The gain at every frequency for the antenna was above 2.2 dB and it increased monotonously with the frequency from 5. 5 GHz to 7. 0 GHz.

Analysis of Metamaterial Cloaks Using Circular Split Ring Resonator Structures

A novel microwave cloak using circular split ring resonator(SRR)based metamaterial structure has been proposed in this paper.The cloak which operates at a frequency of 10.6 GHz is composed of cylindrical dielectric sheets printed with circular split ring resonators of spatially varying and anisotropic material properties.The article also focuses on the phenomenon of resonant splitting in circular SRR microwave cloak.A detailed analysis of various linear metamaterial arrays and their response has also been elucidated.

Orbital Angular Momentum Generation Using Circular Ring Resonators in Radio Frequency

Electromagnetic field generators based on circular ring resonators, whose perimeters are integer times of equivalent wavelength, are well known to have attractive potential for producing radio vortexes carrying orbital angular momentum （OAM）. We study the radiation characteristics of the generators based on radiation vector and antenna array theory. The behaviors of radiation patterns, field intensity and phase distribution are investigated in detail, and show classical features of OAM beams. The evolution of the generators performance versus the OAM state is also analyzed. The proposed generators can be realized by all kinds of microwave transmission lines, verified by two different prototypes. The discussions and conclusions drawn in this study are useful and meaningful for the radio OAM generator design.

Acoustic concept based on an autonomous capsule and a wideband concentric ring resonator for pathophysiological prevention

BACKGROUND Research on the performance of elements constituting our modern environment is constantly evolving,both on a daily basis and on technological basis.But to date,the response of the system to the expectations of the population remains too modest.AIM To elaborate an ultrasonic technique to scan and evaluate in-vivo physiological properties by coupling sensors and multilayer biological tissues model.METHODS A low-frequency ultrasonic method(around a frequency of 32 KHz)based on the use of an innovative autonomous ultrasonic capsule as a miniaturized elementary spherical sensor(1 cm of diameter)and micro-rings resonators were examined.RESULTS Other their functions as passive listeners for the prevention and diagnosis in physiopathology of the respiratory and laryngeal apparatus,these microresonators coupled to the ultrasonic capsule through biological tissues(the body)are capable of evaluating the effects of aggression of the environment on human metabolism.CONCLUSION This would allow consequently the detection of some potential diseases at an early stage,even in people who still represent no symptoms,which would permit an early treatment and a higher chance of cure.

Ultrasensitive terahertz metamaterial sensor based on vertical split ring resonators

An ultrasensitive metamaterial sensor based on double-slot vertical split ring resonators(DVSRRs) is designed and numerically calculated in the terahertz frequency. This DVSRR design produces a fundament LC resonance with a quality factor of about 20 when the incidence magnetic field component normal to the DVSRR array. The resonant characteristics and sensing performance of the DVSRR array design are systematically analyzed employing a contrast method among three similar vertical split ring resonator(SRRs) structures. The research results show that the elimination of bianisotropy, induced by the structural symmetry of the DVSRR design, helps to achieve LC resonance of a high quality factor. Lifting the SRRs up from the substrate sharply reduces the dielectric loss introduced by the substrate. All these factors jointly result in superior sensitivity of the DVSRR to the attributes of analytes. The maximum refractive index sensitivity is 788 GHz/RIU or 1.04 × 10~5 nm∕RIU.Also, the DVSRR sensor maintains its superior sensing performance for fabrication tolerance ranging from -4% to 4% and wide range incidence angles up to 50° under both TE and TM illuminations.

Tunable filters based on an SOI nano-wire waveguide micro ring resonator

Micro ring resonator（MRR） filters based on a silicon on insulator（SOI） nanowire waveguide are fabricated by electron beam photolithography（EBL） and inductive coupled plasma（ICP） etching technology.The cross-section size of the strip waveguides is 450×220 nm2,and the bending radius of the micro ring is around 5μm.The test results from the tunable filter based on a single ring show that the free spectral range（FSR） is 16.8 nm and the extinction ratio（ER） around the wavelength 1550 nm is 18.1 dB.After thermal tuning,the filter＇s tuning bandwidth reaches 4.8 nm with a tuning efficiency of 0.12 nm/℃Meanwhile,we fabricated and studied multi-channel filters based on a single ring and a double ring.After measurement,we drew the following conclusions： during the signal transmission of multi-channel filters,crosstalk exists mainly among different transmission channels and are fairly distinct when there are signals input to add ports.

Novel Design of Ring Resonator Based Temperature Sensor Using Photonics Technology

In the present paper, we study the transmission of the two-dimensional photonic crystal （PC） superellipse ring resonator. The fast growing applications of optomechanical systems lead to strong demands in new sensing mechanism in order to design the sensing elements to nanometer scale. The photonic crystal based resonator has been investigated as promising solutions because the band gap structure and resonator characteristics are extremely sensitive to the deformation and position shift of rod/cavity in PC resonators. This structure opens a single channel filter. The study is extended for tuning of channel filter＇s wavelength with a temperature of this structure. The transmission of the channel filter shows a red shift with temperature linearly. This wavelength shift of the channel filter is used for the sensor application. The sensitivity for the proposed structure is found to be 65.3pm/℃. The outstanding sensing capability renders PC resonators as a promising optomechanical sensing element to be integrated into various transducers for temperature sensing applications.

High-Q ring resonators directly written in As2S3 chalcogenide glass films

Planar ring resonator waveguides are fabricated in thin films of As2S3 chalcogenide glass,deposited on silicaon-silicon substrates.Waveguide cores are directly written by scanning the focused illumination of a femtosecond Ti:sapphire laser at a central wavelength of 810 nm,through a two-photon photo-darkening process.A large photoinduced index change of 0.3–0.4 refractive index units is obtained.The radius of the ring resonator is 1.9 mm,corresponding to a transmission free spectral range of 9.1 GHz.A high loaded（intrinsic） Q value of 110,000（180,000） is achieved.The thermal dependence of the resonator transfer function is characterized.The results provide the first report,to the best of our knowledge,of directly written high-Q ring resonators in chalcogenide glass films,and demonstrate the potential of this simple technique towards the fabrication of planar lightguide circuits in these materials.

Waveguide-type optical passive ring resonator gyro using frequency modulation spectroscopy technique

This paper reports the experimental results of silica on a silicon ring resonator in a resonator micro optic gyroscope based on the frequency modulation spectroscopy technique by our research group. The ring resonator is composed of a 4 cm diameter silica waveguide. By testing at D1550 nm, the FSR, FWHM and the depth of resonance are 3122 MHz, 103.07 MHz and 0.8 respectively. By using a polarization controller, the resonance curve under the TM mode can be inhibited. The depth of resonance increased from 0.8 to 0.8913, namely the finesse increase from 30.33 to 33.05. In the experiments, there is an acoustic-optical frequency shifter（AOFS） in each light loop. We lock the lasing frequency at the resonance frequency of the silica waveguide ring resonator for the counterclockwise lightwave; the frequency difference between the driving frequencies of the two AOFS is equivalent to the Sagnac frequency difference caused by gyro rotation. Thus, the gyro output is observed. The slope of the linear fit is about 0.330 m V/（°/s） based on the 900 to 900 k Hz equivalent frequency and the gyro dynamic range is ±2.0×10^3rad/s.

Electro-optic polymer ring resonator modulators [Invited]

Electro-optic(EO) ring resonator modulators have a number of communications and scientific applications, including analog optical links, optical signal processing, and frequency comb generation. Among the EO materials used to fabricate ring modulators, the EO polymer has many promising characteristics, including a high EO coefficient of 100–200 pm/V(3–7 times larger than that of Li Nb O3), an ultrafast EO response time(< 10 fs), a low dielectric constant(3 to 4) with very little dispersion up to at least 250 GHz, and a straightforward spin-coating fabrication process. These inherent characteristics will be able to combine excellent EO properties with simple processing in achieving exceptional performance in a variety of high-speed optical modulation and sensing devices. This review focuses on the research and recent development of ring resonator modulators based on EO polymers. The first part describes the operation principle of EO ring resonator modulators, such as modulation mechanism, EO tunability, and 3 d B bandwidth. Subsequently, the emphasis is placed on the discussion of the ring modulators with EO polymers as the waveguide core and the improvement of EO modulation by using an EO polymer/titanium dioxide hybrid core. At the end, a series of EO polymers on silicon platforms including slot modulators, etching-free modulators, and athermal modulators are reviewed.

All-optical AND/OR/NOT logic gates based on photonic crystal ring resonators

Photonic crystal based ring resonators are best choice for designing all-optical devices. In this paper, we used a basic structure of photonic crystal ring resonators and designed all optical logic gates which are working using the Kerr effect. The proposed gates consisted of upper and lower wavegnides coupled through a resonator which was designed for dropping of special wavelength. The resonance wavelength was designed for 1550 nm telecom operation wavelength. We used numerical meth- ods such as plane wave expansion and finite difference time domain （FDTD） for performing our simulations and studied the optical properties of the proposed structures. Our results showed that the critical input power for triggering the gate output was lower compared to previously reported gates.

Curvature Sensor Based on a Long-Period Grating in a Fiber Ring Resonator Interrogated by an OTDR

The proposed technique demonstrates a fiber ring resonator interrogated by an optical time domain reflectometer(OTDR),for intensity sensing.By using this methodology,a cavity round trip time of 2.85ms was obtained.For a proof of concept,a long-period grating was inserted in the resonant cavity operating as a curvature sensing device.A novel signal processing approach was outlined,regarding to the logarithmic behavior of the OTDR.Through analyzing the experimental results,an increase in the measured sensitivities was obtained by increasing applied bending.With curvatures performed from 1.8 m^(-1) to 4.5 m^(-1),the sensitivity values ranged from 2.94 dB·km^(-1) to 5.15 dB·km^(-1).In its turn,the sensitivities obtained presented a linear behavior when studied as a function of the applied curvature,following a slope of 0.86×10-3 dB.The advantages of applying this technique were also discussed,demonstrating two similar fiber rings multiplexed in a series of configurations.

An Optical MIM Pressure Sensor Based on a Double Square Ring Resonator

In this paper, we have proposed a metal-insulator-metal （MIM） pressure sensor which consists of two plasmonic waveguides and a double square ring resonator. The two square rings are connected via a rectangular patch located between the two of them. The surface plasmon polaritons （SPPs） can be transferred from a square ring to the other through this patch. The finite-difference time-domain method （FDTD） has been used to simulate the device. Applying a pressure on the structure, it deforms, and a red shift of 103 nm in the resonance wavelength has been calculated. The deformation is linearly proportional to the wavelength shift in a wide range of wavelength. The proposed optical plasmonic pressure sensor has a sensitivity of 16.5nm/MPa which makes it very suitable for using in biological and biomedical engineering.

Single-cavity triangular substrate integrated waveguide bandpass filter with complementary triangular split ring resonator

A novel single-cavity equilateral triangular substrate integrated waveguide(TSIW) bandpass filter(BPF) with a complementary triangular split ring resonator(CTSRR) is designed in this paper. A metallic via-hole is used to split the degenerate modes and adjust the transmission zeros(TZs) properly. Meanwhile, the CTSRR is utilized as a resonator to work together with the degenerate modes of the TSIW cavity. The resonant frequency of the CTSRR can be adjusted by its own size. Meanwhile, a TZ is observed in the lower band due to the CTSRR. Finally, a 16% 3 dB fractional bandwidth(FBW) triple-mode TSIW BPF with three TZs in both lower and upper bands is simulated, fabricated, and measured. There is a good agreement between the simulated and measured ones.

Method for eliminating mismatching error in monolithic triaxial ring resonators

Several results on optical-axis perturbation and elimination of the mismatching error C of a monolithic triaxial ring resonator （MTRR） are reported. Based on the augmented 5×5 ray matrix method, by simultaneously considering axial displacement of a mirror and the misalignments in three planar square ring resonators of a MTRR, the rules of optical-axis perturbation are obtained. The mismatching error C of the MTRR is eliminated. The results obtained are important for cavity design, as well as in the improvement and alignment of MTRR.

A photonic crystal L-shaped bend based on ring resonators

We propose a new type of two-dimensional （2D） photonic crystal L-shaped bent waveguides based on ring resonators with an acceptable bandwidth. The proposed structure mechanism is based on coupling between a waveguide and a ring resonator. This structure is designed and verified by finite-difference time-domain （FDTD） computation. Our simulation using this method gets over 90% output.