A silicon-on-insulator submicron multimode micro-ring resonator symmetrically coupled to two bus waveguides via bent asymmetrical directional coupler to achieve unprecedented-large FSR is proposed ...based on double-injection configuration. An analytical model based on the transfer matrix method is developed to analyze the proposed structure and the physical mechanism for the FSR enlargement is thoroughly analyzed. In addition, the coupling angle is cleverly selected to improve the spectral shape and the extinction ratio at the resonant wavelengths. Finite difference time domain simulations show that ultra large FSRs of 180 nm and 206 nm can be obtained.
•The unprecedented-large FSRs of 180 nm and 206 nm have been achieved via double-injection configuration.•The resonant wavelengths can be switched by simply tuning the additional phase introduced by the phase shifter.•The physical mechanism of FSR doubling and the formation mechanism of the output spectrum, have been analyzed in detail.•We optimize the coupling angle of the bent asymmetrical directional coupler to obtain better spectral shape and extinction ratios.•We believe that the optical add-drop filter based on submicron multimode SOI MRR with double-injection configuration can be better used in ultra-wideband DWDM systems, sensing, optical spectral analyzing, etc.
On-chip photonic generation of tunable wideband phase-coded linearly-chirped microwave waveforms (PC-LCMWs) is proposed and experimentally demonstrated. The on-chip generation system consists of two ...main parts. One part is a hybrid Fourier-domain mode-locked opto-electronic oscillator (FDML-OEO) for a wideband linearly-chirped microwave waveform (LCMW) generation; the other part is a high-speed microwave photonic phase shifter (MPPS) to perform the phase-coding. By synchronizing the two parts, a PC-LCMW is finally generated. In the proposed chip, a thermally-tunable ultrahigh-Q micro-ring resonator (MRR) is a key component which is incorporated in the FDML-OEO loop to select the oscillation frequency, and an electrically-tunable micro-disk resonator (MDR), as another key component, is used to code the phase of the generated microwave signal while maintaining the amplitude by controlling the free carrier concentration in the lateral PN junction of the disk. With the use of the two key component chips, an experiment is performed and different PC-LCMWs are generated with a tunable center frequency from 12 to 16 GHz, a bandwidth from 2 to 6 GHz, and phase code of 7-bit and 13-bit Barker code. In particular, a PC-LCMW with a maximum bandwidth as wide as 6 GHz and an ultra-large time-bandwidth product (TBWP) as large as 1.96×10 6 is experimentally demonstrated. The proposed integrated PC-LCMW generation system holds great advantages including ultracompact configuration and fast tunability, which holds a high potential for applications in modern high-resolution multi-functional radar system.
Training all-optical neural networks in itself remains an unresolved problem, and the challenges compound when the problem is turned into the hardware implementations. In this paper, we propose a ...nonlinear activation function based on optical bistability within a micro-ring resonator (MRR), achieving threshold control without external modulation. Furthermore, a convolutional neural network similar to the Le-Net-5 architecture is designed, in which all nonlinear activation functions are composed of optical bistable hysteresis loop. The numerical simulation results demonstrate that the recognition rate on the Fashion-MNIST dataset can achieve 91.3%, which means that the optical neuromorphic computation can be implemented by utilizing the nonlinear optical effects themselves in the all-optical hardware. Such a scheme promises access to the all-optical neural network training in the optical hardware environment compared to numerical activation functions.
•This paper proposed a nonlinear activation function based on optical bistability within a micro-ring resonator (MRR), achieving threshold control without external modulation. Furthermore, a convolutional neural network similar to the Le-Net-5 architecture is designed, in which all nonlinear activation functions are composed of optical bistable hysteresis loops. The numerical simulation results demonstrate that the recognition rate on the Fashion-MNIST dataset can achieve 91.3%, which means that the optical neuromorphic computation can be implemented by utilizing the nonlinear optical effects themselves in the all-optical hardware.
•We propose a new optical Electrocardiogram (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 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 simulation result shows that the sensitivity of sensor is 11740 pm/V, which can detect ECG signals as small as 10uV, offering the possibility of detecting small ECG waves, such as U wave and J wave.•The proposed DS-PMRR structure can also be easily integrated with other photonic devices at the chip scale, which provides great convenience for miniature ECG sensor.
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.
A compact grating double-slot micro-ring resonator (GDSMRR) based on an SOI platform with a footprint of less than 11 μm ×11μm is analyzed and proposed in order to achieve a refractive index sensor ...with high sensitivity (S) and large measurement range. And EIT-like effects of high Q factor are achieved by combining structure of the double-slot micro-ring and Bragg grating. In the absence of a free spectral range (FSR) limitation, the measurement range of the sensor is significantly improved. In the refractive index sensing applications, Q value is 4325, S value is 433.33 nm/RIU, and DL 8.26 × 10−4 RIU. Thus, the proposed compact GDSMRR with excellent performance has great value for exploration in sensing applications.
•The slot waveguide is used as transmission medium, providing a stronger light confinement ability and has a lower light dissipation in the slot area of low refractive index. Light waves propagating in the slot waveguide are exposed to the external environment. In optical sensing applications, the slot is completely covered and filled by the detected material, which enhances the interaction between light and the external environment and increases the sensing sensitivity of the device.•The EIT-like effect is produced by the interaction of light waves with different resonant wavelengths in GDMRR. Our structure works in a similar way to the cascaded micro-rings, but takes up a very small footprint. The spectral slope of the EIT-like line-shape is sharper and therefore improves the sensitivity.•Side-modes around the main resonance peak of DGMRR are filtered by the wavelength-selective characteristic of the grating. The measurement range of the sensor is significantly improved.•Our structure provides a new method for how to solve the compatibility of high sensitivity and large measurement range of current optical sensors under the premise of a simple structure.•The designed compact device is easy to integrate, suitable for application in sensing arrays, and has great potential in the field of optical sensing.
The electro-optic modulator is an important component in many low cost optical applications especially the ones based on micro-ring for their micromation, low loss etc. In order to enlarge the free ...spectral range and extinction ratio, a U-shaped structure is introduced in the traditional micro-ring electro-optic modulator. Besides, the double-layer graphene separated by a thin insulating layer is used as the tunable material, because its conductivity can be varied upon injection of carriers at optical frequencies. Through numerical simulations, we show that when the distance between two coupling points is equal to the circumference of micro-ring, the FSR is about 130 nm which can reduce the crosstalk in signals during electro-optic modulation greatly. And at the resonance point near λ=1550 nm, when the chemical potential of graphene declines from 0.5 eV to 0.3 eV, the extinction ratio (ER) is about 17dB, also the modulation depth (MD) reaches 98%. In addition, the modulator can be operated with driving voltages below 1.2 V through mainly adjusting the refractive index of the insulating layer. These results promise an efficient electro-optic modulator which will contribute to the applications in large scale on-chip optical interconnects.
•The double-layer graphene separated by a thin insulating layer is used as the tunable material.•The U-shaped structure is introduced which has highly improved its FSR and ER.•At resonance near λ=1550nm, the ER can reach 17dB when μc decreased from 0.5 eV to 0.3 eV, also the MD reaches 98%.•The driving voltage can be reduced less than 1.2V, and the switching energy approaches the level of fJ per bit.•The design will contribute to applications in large scale on-chip optical interconnects.
Sensing nitrate concentrations in soil with high sensitivity and selectivity using field-deployable compact sensor platforms is a sought-after goal for environment and agriculture applications. This ...study demonstrates a new optically based nitrate sensing platform based on ion-selective membrane (ISM) functionalized chip-scale photonic micro-ring resonators. Our approach relies upon measurements of resonance shifts in the micro-resonators and leverages the excellent, though little studied, optical properties of ISMs. Using a high-quality micro-ring resonator, a nitrate ion-selective photonic sensor exhibits a detection limit down to 0.1 parts per million (ppm) and enables nitrate concentration measurements in the 1-100 ppm level, appropriate for soil science and agriculture. Importantly, the sensor also shows high selectivity over other competing anions in soil, such as Cl- and NO2-. Here, we argue that this chip-scale approach can be incorporated into compact sensor platforms.
Multi-dimensional multiplexing plays a vital role in on-chip optical communication for enhancing capacity density. However, the mode (de)multiplexer based on multimode interferometer is generally ...wavelength dependent, which brings a non-negligible conundrum to fabricate multi-dimensional (de)multiplexers. Herein, we propose an on-chip multi-dimensional (de)multiplexer by designing a tapered adiabatic micro-ring resonator (TAMR), and perform a 4-mode bending transmission via a pixelated meta-structure. The TAMR is designed with a negligible wavelength dependence because of non-coherent superposition (No-coherent superposition mechanism based on directional coupling avoids the coherent superposition of light-waves, which will not reduce the working bandwidth.of device.), but employs the periodic energy exchange of evanescent wave between two waveguides to achieve an equal phase velocity for the fundamental and higher-order modes (mode conversion), where a micro-ring resonator array is exploited for resonance frequency selection. A pixelated meta-structure implemented by writing nano airholes in the silicon slab is employed for addressing the mode distortion induced by the bending of transverse electric (TE) modes. Consequently, we construct a 12-channel multi-dimensional (de)multiplexer composed of 3 wavelengths and 4 TE modes. We show that all the channels are successfully (de)multiplexed with crosstalk less than − 19 dB, and bit error rates lower than 3.8 × 10−3 at the signal to noise ratio of 17 dB.
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