Yiping Cui

Bio: Yiping Cui is an academic researcher from Southeast University. The author has contributed to research in topics: Beam propagation method & Waveguide (optics). The author has an hindex of 3, co-authored 4 publications receiving 20 citations.

Resonant frequency shift characteristic of integrated optical ring resonators with tunable couplers

Abstract: Ring resonators integrated with tunable couplers are useful devices in integrated optics systems. The resonant frequency shift characteristic of tunable resonators is theoretically analyzed. It is shown that the resonant frequency shift range is dependent on the configurations and tuning methods of couplers. It provides an analytical explanation of the frequency shift effect by the phase transmission method and the coupled-mode theory (CMT) of asymmetric waveguides. Optimized designs of different kinds of tunable couplers are discussed in order to improve the resonant frequency stability. Moreover, the intensity–phase relationship induced by the resonant frequency shift effect is also discussed, and a more efficient configuration of optical sensors using phase modulation is proposed.

Organic polymer optical waveguide resonance ring

Abstract: An optical waveguide resonant ring of organic polymer type is prepared as adding organic polymer phase controller in loop of said resonant ring to compensate phase variation caused by refractivity variation of resonant ring material, applying thermo-optic effect phase controller as said organic polymer phase controller being formed by phase shifter and modulator as well as frequency shifter

Analysis of ring resonator of integrated optical waveguide gyroscope

Abstract: Ring resonator is a key unit of integrated optical waveguide gyroscope. Generally the Finite Difference Time Domain (FDTD) method is used to analyze the microscopic ring resonator, but this method can not be used to deal with the ring resonator in optical waveguide gyroscope, because the size of the model is too large (the radius of ring resonator is 10 mm). In this paper, an accurate method was demonstrated to design the ring resonator, in which the model was analyzed by together with the Beam Propagation Method (BPM), guided-wave optics and the theory of multiple-beam interference. In this method, the ring resonator was divided into two parts, the coupler and the bend waveguide, and the phase condition of optimum resonance was updated, the phase shift caused by the length of bend waveguide was added upon the propagation phase shift of the coupler. Parameters such as insertion loss y ; coupler coefficient k ; phase shift of the coupler; the propagation constant β, and the bending radiation loss of bend waveguide were obtained accurately by this method. Through the vector analysis, the intensity of resonance of the ring resonator was calculated, and the characteristics of ring resonator were shown. At the end of this paper, the optimization fabrication of optical waveguide resonator was discussed.

An analytical method for curved optical waveguides

Abstract: Analytical method for curved optical waveguides plays an important role in dealing with integrated optical devices based on curved optical waveguides. It helps us not only in understanding physical mechanism of waveguides deeply but also in improving performance of existing integrated devices and designing novel elements. Bend loss of curved optical waveguides is always a problem to be focused on. In order to reduce bend loss of curved optical waveguides, a number of strategies have been used. In this paper, we proposed a new method to analyze curved optical waveguides, which combined the conformal transformation method with ray optical method. An intuitionistic physical image of bend loss in optical waveguides was founded from this point of view, then the reason of bend loss was clearly shown. Accordingly, a new strategy to reduce bend loss in curved optical waveguides was given. Compared with general strategies of modifying the refractive indices whatever in core or cladding, the present strategy is totally deferent. This strategy is beneficial to decrease the radiation of propagation modes in curved optical waveguides by increasing the thickness of curved waveguides. Especially, it is more effective in situations that the radius of curvature of the waveguides and the refractive indices of materials were set beforehand. Software simulation based on BPM was used simultaneously as supplemental verification of this new strategy. Moreover, as an example with this strategy, a special design of ring waveguides structure was given.

High sensitivity optical waveguide accelerometer based on Fano resonance

Abstract: An optical waveguide accelerometer based on tunable asymmetrical Fano resonance in a ring-resonator-coupled Mach–Zehnder interferometer (MZI) is proposed and analyzed. A Fano resonance accelerometer has a relatively large workspace of coupling coefficients with high sensitivity, which has potential application in inertial navigation, missile guidance, and attitude control of satellites. Due to the interference between a high-Q resonance pathway and a coherent background pathway, a steep asymmetric line shape is generated, which greatly improves the sensitivity of this accelerometer. The sensitivity of the accelerometer is about 111.75 mW/g. A 393-fold increase in sensitivity is achieved compared with a conventional MZI accelerometer and is approximately equal to the single ring structure.

Tunable Optical Ring Resonator Integrated With Asymmetric Mach–Zehnder Interferometer

Abstract: We demonstrate theoretically a tunable optical ring resonator incorporating an asymmetric Mach-Zehnder interferometer (MZI) and two phase shifters. The optimal resonance state of the ring resonator with different geometries can be achieved by tuning the two embedded phase shifters. Distinct intensity and phase responses and transmission spectra characteristics are newly observed by setting different structural parameters such as the asymmetrical path lengths of the waveguides and the coupling ratio of the directional couplers in the MZI. The performance characteristics related to the radius of the ring cavity and the propagation losses in the waveguides are also discussed. At optimal resonance, it is shown that sharp intensity response and tunable narrow-bandwidth spectra can be achieved especially for resonators with a highly asymmetrical configuration. Such device has a potential in sensing, switching and filtering applications.

Compact wavelength- and bandwidth-tunable microring modulator.

Abstract: Fabrication errors currently hold back the large-scale adoption of silicon micro-ring modulators (MRMs). The ability to correct their spectral features post-fabrication is required to enable their commercialization. Here, we report and demonstrate an MRM that uses a tunable two-point coupling scheme, which maintains the MRM’s compact footprint (60 µm×45 µm) and allows one to tune the MRM’s operating wavelength and adjust the optical bandwidth (and/or extinction ratio). This means that one can compensate for fabrication errors and thereby improve the yields. We confirm the modulator’s operation by showing NRZ and PAM-4 modulation, up to 28 Gb/s and 19.9 Gb/s, respectively. Also, the proposed tunable MRM maintains the microring’s free-spectral range (FSR), which proves its compatibility for configurable and high-bandwidth DWDM applications.

Bandwidth-tunable, FSR-free, microring-based, SOI filter with integrated contra-directional couplers.

Abstract: A silicon-on-insulator (SOI), bandwidth (BW)-tunable, free-spectral-range (FSR)-free, microring resonator (MRR)-based filter is experimentally demonstrated. The device achieves an FSR-free response at its through and drop ports by using a grating-assisted coupler in one coupling region of the MRR and achieves a non-adjacent channel isolation, (nAi), for 400 GHz WDM, greater than 26.7 dB. A thermally tunable Mach–Zehnder Interferometer-based coupling scheme is also utilized to compensate for fabrication variations and enable the BW tunability of the filter. The BW of the filter can be continuously tuned from 25 to 60 GHz while maintaining an nAi greater than 26.7 dB.

Tunable microring resonator based on dielectric-loaded surface plasmon polariton waveguides.

Abstract: Integrated optical ring resonators are essential elemental components for integrated optical circuits. An ultrasmall thermo-optical microring resonator with two bus waveguide-configuration based on surface plasmon polariton waveguide is theoretically analyzed. The thermo-optical coefficient, the temperature-dependent amplitude attenuation coefficient and the temperature distribution properties of the waveguide are investigated numerically by finite element method. The critical resonant conditions of the microring resonator are discussed by considering the propagation losses in the plasmonic ring cavity. The transmission characteristics and the tunability of the ring resonator with different structural parameters are investigated. The results show that the proposed ring resonator with a low driving power and high efficient tunability has potential to develop nano-scope wavelength tunable channel drop filters, low power optical switches, attenuators, and other high compact integrated optical devices.