Slow light in silicon microring resonators

This paper experimentally investigated slow light effect in cascaded silicon-on-insulator (SOI) microring resonators.Double channel and single channel sidecoupled integrated spaced sequence of resonators (SCISSOR) devices were fabricated with electron beam lithography and dry etching technology.The delay performances of the SCISSOR devices were demonstrated using non-return-to-zero (NRZ) and return-to-zero (RZ)signals at different bit rates.Group delays and bandwidths of cascaded microrings are significantly enhanced compared with single microring.     

基于光学微环的化学传感器

以SiN为材料,采用与CMOS工艺相兼容的技术,制备了波导宽度为1μm,半径为400μm的SiN光学微环。经测量,其品质因数(Q值)高达20 000,自由光谱范围(FSR)为0.5 nm。提出了采用光学微环传感器、单波长光源和光功率计对待测物进行测量的方案。实验证明,该方案与传统的采用光谱仪测量谐振峰值漂移的方法相比,可以取得更高的系统探测灵敏度。最后,利用微环传感器对葡萄糖溶液浓度进行测量,灵敏度高达10-4折射率单元(RIU),证明了该传感器可以应用于溶液检测领域。     

All-optical nonlinear switching in GaAs-AlGaAs microring resonators

In this paper, we demonstrate all-optical nonlinear switching in compact GaAs-AlGaAs microring resonators at the 1.55-μm wavelength. Switching is accomplished in the pump-and-probe configuration in which the pump-and-probe signals are tuned to different resonance wavelengths of the microring. Refractive index change in the microring due to free carriers generated by two photon absorption is used to switch the probe beam in and out of resonance. Measured transient responses of the pump and probe through the microring show good agreement with theoretical predictions based on nonlinear pump-probe interaction due to two photon absorption     

Optimum design of a polymer electro-optic microring resonator switch

Novel transfer functions are presented for a polymer electro-optic microring resonator switches. The resonating process of the light in the microring is simulated using the formulas. Then the optimization of the structural parameters is performed, and the characteristics are analyzed, such as the resonance time, output spectrum, operation voltage, insertion loss and crosstalk were analyzed. The simulation results show that the designed device exhibits favorable switching functions.     

Box-like spectral response of a series-coupled microring resonant filter in a parallel channel

Inthelast decades ,microring resonator( MRR) wave-lengthfilters are developed rapidly because of their po-tential applications in wavelength division multiplexing( WDM) communicationsystems andtheir excellent fea-tures includingfunctionality,compactness a…     

Vertically coupled microring resonators using polymer wafer bonding

A new technique is presented to make vertically coupled semiconductor microring resonators that eases the fabrication process with devices more robust to ring-to-waveguide misalignments. Single-mode microring optical channel dropping filters are demonstrated for the first time in this configuration with Qs greater than 3000 and an on-resonance channel extinction greater than 12 dB. A 1×4 multiplexer/demultiplexer crossbar array with second-order microrings was also made and exhibited channel-to-channel crosstalk lower than 10 dB     

Analysis of nonblocking ATM switches with multiple input queues

An analytical model for the performance analysis of a multiple input queued asynchronous transfer mode (ATM) switch is presented. The interconnection network of the ATM switch is internally nonblocking and each input port maintains a separate queue of cells for each output port. The switch uses parallel iterative matching (PIM) to find the maximal matching between the input and output ports of the switch. A closed-form solution for the maximum throughput of the switch under saturated conditions is derived. It is found that the maximum throughput of the switch exceeds 99% with just four iterations of the PIM algorithm. Using the tagged input queue approach, an analytical model for evaluating the switch performance under an independent identically distributed Bernoulli traffic with the cell destinations uniformly distributed over all output ports is developed. The switch throughput, mean cell delay, and cell loss probability are computed from the analytical model. The accuracy of the analytical model is verified using simulation     

Analysis model of multiple input-queued switches with PIMscheduling algorithm

In this letter, we propose a new analysis model of multiple input-queued switches that use the parallel iterative matching (PIM) scheduling algorithm under i.i.d Bernoulli traffic. Compared to the previous analysis models, our approach incurs very low computational complexity while maintaining good accuracy by employing a simple queueing model. Specifically, we model an input queue of the switch as a synchronous Geom/Geom/1/B queue with a service rate which is directly obtained from a PIM scheduling algorithm. We perform the simulation and verify the accuracy of our model     

Deep glass etched microring resonators based on silica-on-silicon technology

Microring resonators fabricated on silica-on-silicon technology using deep glass etching are demonstrated. The fabrication procedures are introduced and the transmission spectrum of a resonator is presented.     

Parallel-cascaded semiconductor microring resonators for high-order and wide-FSR filters

We demonstrate an optical channel dropping filter (OCDF) using three parallel-cascaded vertically coupled microrings with improved rolloff, bandpass flattening, and wide free spectral range (FSR) compared to a single-ring OCDF using single-mode tightly confined waveguides in both GaAs-AlGaAs and GaInAsP-InP. We achieve FSRs of 30 nm for GaAs-AlGaAs and 40 nm for GaInAsP-InP devices, which are three and four times greater, respectively, than those for single rings. The rolloff is 2.8 times faster than that for a single ring.     

Asymmetrically coupled silicon-on-insulator microring resonators for compact add-drop multiplexers

We report on improved filter characteristics of microring resonators (MRs) used as add-drop multiplexers for integrated photonic circuits. By introducing an asymmetrical coupling of the signal waveguides to the resonator, a higher throughput attenuation and drop efficiency is attained. The throughput attenuation is the decisive property for the application of microrings in photonic networks since it determines the crosstalk between drop signal and add signal at the throughput channel of an add-drop multiplexer. Experimental results are compared with analytical relations. MRs with a free-spectral range of 24 nm are fabricated on silicon-on-insulator substrates. A crosstalk reduction by 8.8 dB due to asymmetrical coupling is demonstrated.     

Propagation loss in single-mode GaAs-AlGaAs microring resonators:measurement and model

We report propagation loss measurements in single-mode GaAs-AlGaAs racetrack microresonators with bending radii from 2.7 μm to 9.7 μm. The experimental data were found to be in good agreement with a physical-loss model which accounts for the bending loss, the scattering loss due to surface roughness on the waveguide sidewalls, and the transition loss at the straight-to-bend waveguide junctions. The model also enables us to identify the dominant loss mechanisms in semiconductor microcavities. We found that for racetracks with large bending radii (greater than 4 μm, in our case) the loss due to surface-roughness scattering in the curved waveguides dominates, whereas for small-radius rings, the modal mismatch at the straight-to-bend waveguide junctions causes the biggest loss. This result suggests that circular-shaped rings are preferable in the realization of ultrasmall low-loss microcavities. We also show that the round-trip propagation loss in small-radius racetrack microresonators can be minimized by introducing a lateral offset at the straight-to-bend waveguide junctions     

基于两次衰减全反射结构的电光开关的研究

为了进一步提高电光开关的消光比,利用双面金属包覆波导激发的高阶导模是导波层折射率的灵敏函数这一特性,采用同一入射光束在波导中实现二次衰减全反射的方法,设计了一种快速响应的聚合物波导电光开关,并进行了理论分析和实验验证.得到该器件的消光比高达38dB,开关的响应时间低于110ns.结果表明,该电光开光器件具有动态范围大、驱动电压低、响应速率快、插入损耗小、器件稳定性能高以及制备工艺简单等诸多特点.这一结果对光互联、集成光路以及无线光通信等领域的应用是有帮助的.     

Investigation of an all-optical wavelength converter with reshaping properties based on four-wave mixing in passive microring resonators

The properties of an all-optical wavelength converter with reshaping characteristics, based on four-wave mixing (FWM) in a passive GaAs-AlGaAs microring resonator side-coupled to a bus waveguide, are investigated in this paper. The reshaping properties are based on the nonlinear FWM transfer function as a result of the two-photon absorption enhanced by the resonance effect. A detailed study of the static and dynamic reshaping characteristics of the wavelength converter has been carried out. Its performance, evaluated by extinction ratio and Q-factor calculations, showed satisfactory regenerative properties up to 10 Gb/s.     

Analysis of a racetrack microring resonator with MMI coupler

The static spectral characteristic response of a ring resonator in the form of racetrack with a multimode interference (MMI) coupler has been numerically simulated and investigated. The generalized multimode transmission matrix of the MMI has been evaluated with beam-propagation method simulation and furthermore, the effect of the excitation of higher order modes in the ring resonator on the device-transmission characteristic has been analyzed.     

Analysis of satellite on-board time-space-time switching networkswith multiple separated space switches

Advanced satellite on-board baseband switching processors have time-space-time (T-S-T) structures which are similar to the terrestrial switching networks (Sw-Nw). Generally, the satellite systems require higher reliability than ground equipment because of more severe environment and lack of repair. This paper proposes fault-tolerant satellite on-board T-S-T Sw-Nw with multiple separated space switches instead of a single spare switch. The authors analyze the mean time to unreliable operation (MTUO), as a performance and reliability index for the T-S-T systems with multiple separated space switches as well as conventional T-S-T systems. The MTUO varies depending on the threshold level of blocking-probability and the offered traffic. In general, T-S-T Sw-Nw with multiple space switches have better performance and reliability than those with the single space switch, and their performabilities are appreciably improved, especially for one additional spare space switch. This study can be extended to analyze the performance and reliability of entire satellite communication systems including the on-board baseband Sw-Nw, Rx interfaces, and Tx interfaces     

Throughput analysis for multicast switches with multiple input queues

This letter analyzes the saturated throughput for multicast switches with multiple input queues per input port. Under the assumptions of a Poisson uniform traffic model and random packet scheduling policy, we derive the multicast switch saturated throughput under different fanouts. To verify the analysis, extensive simulations are conducted with different switch sizes and fanouts. It is shown that the theoretical analysis and the simulation results have a discrepancy less than 1.9%. Results from this letter can be used as a guidance to design the optimal queuing for multicast switches.     

Second-order filter response with series-coupled silica microresonators

We have demonstrated an approach for fabricating a photonic filter with second-order response function. The filter consists of two germania-doped silica microtoroidal or microspherical resonators cascaded in series. We use ultraviolet irradiation to tune the mode of one microcavity to bring it close to the mode of the second microcavity. This approach produces a filter function with much sharper rolloff than can be obtained with the individual microresonators.     

Analysis of open resonators

A multiple reflection approach is employed to examine the properties of the lowQ open resonators commonly used in high power gyrotrons. The resonant frequency, diffractionQ, and RF field profile are derived in closed forms in the lowQ limit. Formation of the eigenmode in the resonator is shown as the result of constructive wave interference. The lower limit ofQ in the context of a conventional definition ofQ is derived.     

First 8*8 semiconductor optical matrix switches using GaAs/AlGaAs electro-optic guided-wave directional couplers

Monolithically integrated 8*8 semiconductor optical matrix switches have been successfully fabricated for the first time. They were constructed on GaAs from 64 GaAs/AlGaAs electro-optic directional couplers using a simplified tree architecture. The devices have a chip size of 26.5*3 mm/sup 2/ and a minimum total loss (excluding coupling loss) of 8.7 dB.<>