Modified Ring Resonator Research Articles

A Millimeter-Wave Frequency Reconfigurable Circularly Polarized Antenna Array

This paper discusses the design of a high gain right-hand circularly polarized millimeter-wave frequency reconfigurable antenna array. The 16-element antenna array is designed to reconfigure its operating frequency over both K- and Ka-bands. More specifically, the reconfigurability is ensured through the integration of a modified ring resonator along with the array's sequentially rotated stacked feeding network. The ring resonator is designed to reconfigure its operating frequency over four distinct bands with center frequencies at 25 GHz, 26 GHz, 27.75 GHz and 29 GHz, respectively. Such integration enables the proposed millimeter-wave antenna array to exhibit unique radiation characteristics by maintaining circular polarization with an Axial Ratio (AR) <; 1 dB in a fractional bandwidth of 37.5% between 21.2 GHz and 31 GHz. A Figure of Merit that takes into account the array's axial ratio, sidelobe levels and fractional bandwidth is developed to highlight the unique performance of the presented millimeter-wave circularly polarized array in comparison to available work in the literature. The fabricated antenna array shows good agreement with the simulated data where it is found that the measured realized gain exceeds 12 dBic with sidelobe levels of less than -17.5 dB over the various frequency bands of the frequency reconfigurable antenna array.

Creating locally interacting Hamiltonians in the synthetic frequency dimension for photons

The recent emerging field of synthetic dimension in photonics offers a variety of opportunities for manipulating different internal degrees of freedom of photons such as the spectrum of light. While nonlinear optical effects can be incorporated into these photonic systems with synthetic dimensions, these nonlinear effects typically result in long-range interactions along the frequency axis. Thus, it has been difficult to use the synthetic dimension concept to study a large class of Hamiltonians that involves local interactions. Here we show that a Hamiltonian that is locally interacting along the synthetic dimension can be achieved in a dynamically modulated ring resonator incorporating χ ( 3 ) nonlinearity, provided that the group velocity dispersion of the waveguide forming the ring is specifically designed. As a demonstration we numerically implement a Bose–Hubbard model and explore photon blockade effect in the synthetic frequency space. Our work opens new possibilities for studying fundamental many-body physics in the synthetic space in photonics, with potential applications in optical quantum communication and quantum computation.

Silicon ring resonator electro-optical modulator utilizing epsilon-near-zero characteristics of indium tin oxide

One crucial component in optical communication systems is the optical modulator. It links between the electric and optical domains as it transforms the electric signal into an optical stream. Electro-optical modulation is a very popular scheme. Recently, indium tin oxide (ITO) has been intensively used in optical modulators due to its epsilon-near-zero characteristics. A silicon electro-optic ring resonator modulator is proposed in terms of the outspread application of ITO. An extinction ratio of about 14 dB as well as an insertion loss of 0.075 dB are achieved at a standard telecommunication wavelength of 1.55 microns. The design has low losses, high efficiency, and compact size.

CMOS-compatible, piezo-optomechanically tunable photonics for visible wavelengths and cryogenic temperatures.

We demonstrate a platform for phase and amplitude modulation in silicon nitride photonic integrated circuits via piezo-optomechanical coupling using tightly mechanically coupled aluminum nitride actuators. The platform, fabricated in a CMOS foundry, enables scalable active photonic integrated circuits for visible wavelengths, and the piezoelectric actuation functions without performance degradation down to cryogenic temperatures. As an example of the potential of the platform, we demonstrate a compact (∼40 µm diameter) silicon nitride ring resonator modulator operating at 780 nm with intrinsic quality factors in excess of 1.5 million, >10 dB change in extinction ratio with 2 V applied, a switching time less than 4 ns, and a switching energy of 0.5 pJ/bit. We characterize the exemplary device at room temperature and 7 K. At 7 K, the device obtains a resistance of approximately 20 teraohms, allowing it to operate with sub-picowatt electrical power dissipation. We further demonstrate a Mach-Zehnder modulator constructed in the same platform with piezoelectrically tunable phase shifting arms, with 750 ns switching time constant and 20 nW steady-state power dissipation at room temperature.

Microring Switching Control Using Plasmonic Ring Resonator Circuits for Super-Channel Use

The multi-wavelength selection and switching system using the hybrid plasmonic add-drop ring resonator (HPARR) for optical communication is proposed for multi-carrier super-channel-based designed. The plasmonic polariton technique applied in the ring resonator mode to the alternate waveguide interferometer switches the multi-wavelength laser emission in the various ranges. The combination of curvature-coupled plasmon ring and substances with different refractive index allows switching the multi-wavelength emission to shorter the free spectrum range (FSR) and specific wavelengths, without an applied pump signal or adjusted the ring size. It is suitable for the super-channel of wavelength division multiplex (WDM) in the future optical network.

Frequency Matching of Orthogonal Wineglass Modes in Disk and Ring Resonators Made From (100) Silicon

Vibrational wineglass modes in disk and rings that are made from (100) silicon are considered. It is shown that all odd-ordered wineglass modes are necessarily frequency matched, each with its orthogonal conjugate. In contrast, all even-ordered wineglass modes are likely not to be frequency matched with their orthogonal conjugate. Some specific cases are presented that show that many wineglass modes do not have a rotational periodic symmetry. This is relevant to disks and rings that are driven and sensed by surrounding gap-closing electrostatic actuators.

Analog Signal Modulation Using an All-Polymer Ring Resonator Modulator

Electro-optic ring resonator modulators (RRMs) are designed and fabricated on an all-polymer platform. A fabrication technique is developed for all-polymer electro-optic modulators based on commercially available polymer materials. Fabricated RRMs are characterized showing Q-factor of ~44000 and electro-optic coefficient of ~89 pm/V. Targeting RRM implementations in RF photonic links the nonlinearity of analog signal modulation is characterized in fabricated RRM presenting suppression of second and third harmonics at specific modulation points of the Lorentzian transfer function as predicted by theoretical studies. The third harmonic distortion is suppressed by ~37 dB, while the fundamental signal decreases by ~4 dB from maximum modulation index operational point showing the unique capability of RRMs in enhancing microwave photonic links spur-free dynamic ranges in terms of third-order intermodulation distortion.

Electromagnetically induced transparency in sinusoidal modulated ring resonator

In the present work, we demonstrate controlling the excitation of bright mode (continuum mode) resonance and dark mode (discrete mode) resonance in a planar metasurface made of sinusoidal modulation inside a closed rectangular metallic ring placed over a dielectric substrate. Unlike asymmetrical breaking of a meta-atom (often referred to as the unit cell) to achieve the dark mode response in regular metamaterials, in the present structure, the bright or dark mode resonance is achieved using even or odd half cycle modulation. The achieved dark-mode shows a sharp resonance for a particular polarization of the incident electric field, which results in an electromagnetically induced transparency like spectrum. The electromagnetic behavior of the proposed meta-atom has been investigated in the frequency domain using commercially available software and validated through experiments in the gigahertz regime.

Tunable Supermode Dielectric Resonators for Axion Dark-Matter Haloscopes

We present frequency tuning mechanisms for dielectric resonators, which undergo "super-mode" interactions as they tune. The tunable schemes are based on dielectric materials strategically placed inside traditional cylindrical resonant cavities, necessarily operating in Transverse Magnetic modes for use in axion haloscopes. The first technique is based on multiple dielectric disks with radii smaller than that of the cavity. The second scheme relies on hollow dielectric cylinders similar to a Bragg resonator, but of different location and dimension. In particular we engineer a significant increase in form factor for the TM030 mode utilising a variation of a Distributed Bragg Reflector Resonator. Additionally, we demonstrate application of traditional Distributed Bragg Reflectors in TM modes, which may be applied to a haloscope. This is the first demonstration of Bragg resonators applied to TM modes, as well as the first application of super-modes to tune Bragg resonators, or haloscope resonators. Theory and experimental results are presented showing an increase in Q-factor and tunability due to the super-mode effect. The TM030 ring resonator mode offers between 1 and 2-orders-of-magnitude improvement in axion sensitivity over current conventional cavity systems and will be employed in the forthcoming ORGAN experiment.

Frequency comb generation in a silicon ring resonator modulator.

We report on the generation of an optical comb of highly uniform in power frequency lines (variation less than 0.7 dB) using a silicon ring resonator modulator. A characterization involving the measurement of the complex transfer function of the ring is presented and five frequency tones with a 10-GHz spacing are produced using a dual-frequency electrical input at 10 and 20 GHz. A comb shape comparison is conducted for different modulator bias voltages, indicating optimum operation at a small forward-bias voltage. A time-domain measurement confirmed that the comb signal was highly coherent, forming 20.3-ps-long pulses.

Linearity optimizations of analog ring resonator modulators through bias voltage adjustments

The linearity of ring resonator modulator (RRM) in microwave photonic links is studied in terms of instantaneous bandwidth, fabrication tolerances, and operational bandwidth. A proposed bias voltage adjustment method is shown to maximize spur-free dynamic range (SFDR) at instantaneous bandwidths required by microwave photonic link (MPL) applications while also mitigating RRM fabrication tolerances effects. The proposed bias voltage adjustment method shows RRM SFDR improvement of ∼5.8 dB versus common Mach–Zehnder modulators at 500 MHz instantaneous bandwidth. Analyzing operational bandwidth effects on SFDR shows RRMs can be promising electro-optic modulators for MPL applications which require high operational frequencies while in a limited bandwidth such as radio-over-fiber 60 GHz wireless network access.

Electro‐optic Polymer Ring Resonator Modulator on a Flat Silicon‐on‐Insulator

AbstractOptical polymers are a promising material of choice in the development of hybrid silicon photonics devices. Particularly, recent progress in electro‐optic (EO) active polymers has shown a strong Pockels effect. A ring resonator modulator is a vital building block for practical applications, such as signal processing, routing, and monitoring. However, the properties of the hybrid silicon and EO polymer ring modulators are still far from their theoretical limits. Here, we demonstrate a unique design of a hybrid ring resonator modulator simply located onto a silicon‐on‐insulator (SOI) substrate. Extra doping and etching of the SOI wafer is not required, even so we measured an in‐device electro‐optic coefficient r33 = 129 pm/V. The ring modulator exhibited a high sensitivity of the electrically tunable resonance, which enabled a 3 dB bandwidth of up to 18 GHz. The proposed technique will enable efficient mass‐production of the micro‐footprint modulators and promote the development of integrated silicon photonics.

Tunable wavelength demultiplexer using modified graphene plasmonic split ring resonators for terahertz communication

This paper presents graphene modified ring resonator based wavelength demultiplexer (WDM) for THz device applications that is, a surface plasmon polaritons (SPPs) demultiplexer consisting of two nanostrip waveguides at input as well as output coupled to each other by a split ring resonator (SRR), which is modified in shape as compared to a simple ring-shaped resonator. A systematic analysis of the transmission spectra for the graphene based SRR poses clear insight on the demultiplexing phenomenon of the proposed nanodevice. The results show resonance peaks in the transmission spectrum, having a linear relationship with the chemical potential of graphene. The influence of structural parameters have also been analyzed. The tuning capability of graphene based tunable WDM, lays its foundation in the applications of optical switches, modulators, etc.

Silicon Photonics Transmitter with SOA and Semiconductor Mode-Locked Laser

We experimentally investigate an optical link relying on silicon photonics transmitter and receiver components as well as a single section semiconductor mode-locked laser as a light source and a semiconductor optical amplifier for signal amplification. A transmitter based on a silicon photonics resonant ring modulator, an external single section mode-locked laser and an external semiconductor optical amplifier operated together with a standard receiver reliably supports 14 Gbps on-off keying signaling with a signal quality factor better than 7 for 8 consecutive comb lines, as well as 25 Gbps signaling with a signal quality factor better than 7 for one isolated comb line, both without forward error correction. Resonant ring modulators and Germanium waveguide photodetectors are further hybridly integrated with chip scale driver and receiver electronics, and their co-operability tested. These experiments will serve as the basis for assessing the feasibility of a silicon photonics wavelength division multiplexed link relying on a single section mode-locked laser as a multi-carrier light source.

Fiber Optic Magnetic Field Sensor Based on Magnetic Nanoparticle Assembly in Microcapillary Ring Resonator

A magnetic field sensor based on the magnetic-field-induced nanoparticle assembly effect in microcapillary whispering gallery mode (WGM) ring resonator is proposed and experimentally demonstrated. The chemical characteristics of nanoparticles and the silica microcapillary are used to link up the surface density of the resonator and the magnetic field intensity. The magnetic field variation changes the surface density of nanoparticles adsorbed on the sensor surface and respond to the WGM transmission spectra shift. Because of the powerful surface sensing capability of WGM, the maximum sensing sensitivity reaches 57.59 nm/mT and the detection limit reaches 1.39 × 10 –4, respectively. The magnetic field response characteristic of the sensor is studied as well. This provides the potential to fiber-based magnetic field sensing applications.

Off-resonant Raman quantum memory in impurity crystals: signal-to-noise ratio analysis

The possibility of implementing an off-resonant Raman scheme of optical quantum memory on the basis of an ensemble of three-level atoms is investigated under the condition of equal polarisations of resonant transitions forming the Λ-scheme. The developed model is used to analyse the signal-to-noise ratio at the output of an optical quantum memory device in 143Nd3+ : Y 7LiF4. It is shown that this ratio can significantly exceed unity for single-photon input pulses. The required values of the parameters can be obtained by using an impurity crystal in the form of a whispering-gallery mode ring resonator.

Spurious free independently controllable compact quad‐band filter using folded T‐shaped stub loaded modified ring resonator

A compact spurious free, quad-band, band-pass filter (BPF) having independently controllable and widely spaced frequency bands is proposed. The design consists of a basic BPF to which the authors introduce transmission zeros (TZs) in the frequency response using T-shaped stubs loaded with a modified ring resonator (MRR) thereby creating the four passbands. This design results in very high band-to-band isolation. The TZs are obtained by transversal signal path cancellation and also due to the loaded T-shaped stubs. The BPF consists of a stepped impedance low-pass filter which provides spurious free out of band characteristics up to 20 GHz. By changing the tapping position of the MRR, the frequencies of the TZs can be adjusted to get the desired pass band characteristics. The proposed quad-band filter provides low-insertion loss (<1 dB) at the four passbands centred at 2.4, 5.1, 7.7 and 10.1 GHz. The simulation results of the filter are verified experimentally.

Generating EPR-entangled mechanical state via feeding finite-bandwidth squeezed light**Projects supported by the National Natural Science Foundation of China (Grant Nos. 61505014 and 11504031), the Yangtze Youth Talents Fund, and the Yangtze Funds for Youth Teams of Science and Technology Innovation (Grant No. 2015cqt03).

Einstein–Podolski–Rosen (EPR) entanglement state is achievable by combining two single-mode position and momentum squeezed states at a 50:50 beam-splitter (BS). We investigate the generation of the EPR entangled state of two vibrating membranes in a ring resonator, where clockwise (CW) and counter-clockwise (CCW) travelling-wave modes are driven by lasers and finite-bandwidth squeezed lights. Since the optomechanical coupling depends on the location of the membranes, CW and CCW can couple to the symmetric and antisymmetric combination of mechanical modes for a suitable arrangement, which corresponds to a 50:50 BS mixing. Moreover, by employing the red-detuned driving laser and tuning the central frequency of squeezing field blue detuned from the driving laser with a mechanical frequency, the squeezing property of squeezed light can be perfectly transferred to the mechanical motion in the weak coupling regime. Thus, the BS mixing modes can be position and momentum squeezed by feeding the appropriate squeezed lights respectively, and the EPR entangled mechanical state is obtained. Moreover, cavity-induced mechanical cooling can further suppress the influence of thermal noise on the entangled state.

High-bandwidth photonic-crystal-based ring resonator pin modulator

The present study described a photonic-crystal-based ring resonator pin modulator on an InP-substrate. The device geometry was based on a single ring resonator coupled to one straight waveguide by creating line defect holes through slab layer stack InP/InGaAsP/InP having a hexagonal lattice. The radius of the hole was calculated to be 187nm with a lattice constant of 500nm. The distribution of carriers and the electrical field in the guiding and cladding layers determined the effective refractive index of the ring resonator. Transient analysis of the pin modulator was carried out by applying a pulse to the electrodes that switched between 0 and −7V. The frequency response of the ring resonator modulator shows over 300GHz of bandwidth.

Efficiency Optimization of Silicon Photonic Links in 65-nm CMOS and 28-nm FDSOI Technology Nodes

Optical interconnects for system-in-package applications can be designed for various bit rates. In this paper, an optimization study is conducted to find the optimal parameters for electrooptical links, based on a silicon photonic technology. We focus on the bit rate to achieve highest possible power efficiencies. This paper takes all the elements of an electrooptical link into account: serialization stage, ring-resonator-based modulator, thermal stabilization, modulator driver, laser, receiver, deserialization stage, and clock-phase generation. The optimization is based on a simulation-supported database for single-ended transimpedance amplifiers (TIAs). For all the other, elements of the link simulation-based power consumption models are presented. Furthermore, an analytical solution for the TIA bandwidth and bit rate relationship is derived based on the system jitter, the TIA noise, transimpedance, bandwidth and minimal output swing, and the available input signal. Optimal bit rates are derived and discussed for a 65-nm CMOS and a 28-nm fully depleted silicon-on-insulator technology. We found that the optimal bit rates increase with more aggressive technology scaling and smaller photodiode capacitances, but decrease if lower static power consumptions can be achieved (e.g., by efficient thermal tuning of ring-resonator modulators). We conclude that further research should aim for lower tuning powers instead of higher speed.