Tunable optical filter using second-order micro-ring resonator

In this paper, we design and fabricate a silicon integrated optical filter consisting of two cascaded micro-ring resonators and two straight waveguides. Two micro-heaters are fabricated on the top of two micro-rings respectively, which are employed to modulate the micro-rings to perform the function of a tunable optical filter by the thermo–optic effect. The static response test indicates that the extinction ratio and 3-d B bandwidth are 29.01 d B and 0.21 nm respectively, the dynamic response test indicates that the 10%–90% rise and 90%–10% fall time of the filter are 16 μs and 12 μs, respectively,which can meet the requirements of optical communication and information processing. Finally, the power consumption of the device is also characterized, and the total power consumption is about 9.43 m W/nm, which has been improved efficiently.

Research progress of integrated optical gyroscope

Integrated optical gyroscopes(IOGs)have been an efficient tool for numerous applications in various fields,including inertial navigation,flight control,and earthquake monitoring.Here,we review the progress of integrated optical gyroscopes based on two categories of integrated interferometric optical gyroscopes(IIOGs)and integrated resonant optical gyroscopes(IROGs).

Stochastic averaging of quasi integrable and resonant Hamiltonian systems excited by fractional Gaussian noise with Hurst index 1/2

A stochastic averaging method of quasi integrable and resonant Hamiltonian systems under excitation of fractional Gaussian noise （fGn） with the Hurst index 1/2 〈 H 〈 1 is proposed. First, the definition and the basic property of fGn and related fractional Brownian motion （iBm） are briefly introduced. Then, the averaged fractional stochastic differential equations （SDEs） for the first integrals and combinations of angle variables of the associated Hamiltonian systems are derived. The stationary probability density and statistics of the original systems are then obtained approximately by simulating the averaged SDEs numerically. An example is worked out to illustrate the proposed stochastic averaging method. It is shown that the results obtained by using the proposed stochastic averaging method and those from digital simulation of original system agree well.

Resonator integrated optic gyro based on multilevel laser frequency lock-in technique

The resonator integrated optic gyros（RIOGs） based on the Sagnac effect have gained extensive attention in navigation and guidance systems due to their predominant advantages： high theoretical accuracy and simple integration. However, the problems of losing lock and low lock-in accuracy are the bottlenecks, which restrict the development of digital RIOGs. Therefore, a multilevel laser frequency lock-in technique has been proposed in this Letter to address these problems. The experimental results show that lock-in accuracy can be improved one order higher and without losing lock in a variable temperature environment. Then, a digital miniaturized RIOG prototype（18 cm × 18 cm × 20 cm） has been produced, and long-term（1 h） bias stability of 26.6 deg/h is successfully demonstrated.

Multiwavelength generation using an add-drop microring resonator integrated with an InGaAsP/InP sampled grating distributed feedback

A system of an add-drop microring resonator integrated with a sampled grating distributed feedback （SG-DFB） is investigated via modeling and simulation with the time-domain traveling wave （TDTW） method. The proposed microring resonator comprises a SiO2 waveguide integrated with an InGaAsP/InP SG-DFB, and the SiO2 waveguide consists of a silicon core having a refractive index of 3.48 and Kerr co- efficient of 4.5 × 10^-18 m2/W. The SG-DFB consists of a series of grating bursts that are constructed using a periodic apodization function with a burst spacing in the grating of 45 μm, a burst length of 5 μm, and I0 bursts across the total length of the SG-DBR. Transmission results of the through and drop port of the microring resonator show the significant capacity enhancement of the generated center wavelengths. The Q-factor of the microring resonator system, defined as the center wavelength （λ0） divided by 3 dB FWHM, without and with integration with the SG-DFB is calculated as 1.93 × 10^5 and 2.87 × 10^5, respectively. Analysis of the dispersion of the system reveals that increasing the wavelength results in a decrease of the dispersion. The higher capacity and efficiency are the advantages of integrating the microring resonator and the InGaAsP/InP SG-DFB.

Real-time detection of influenza A virus using semiconductor nanophotonics

Modern miniaturization and the digitalization of characterization instruments greatly facilitate the diffusion of technological advances in new fields and generate innovative applications.The concept of a portable,inexpensive and semi-automated biosensing platform,or lab-on-a-chip,is a vision shared by many researchers and venture industries.Under this scope,we present a semiconductor monolithic integration approach to conduct surface plasmon resonance studies.This technology is already commonly used for biochemical characterization in pharmaceutical industries,but we have reduced the technological platform to a few nanometers in scale on a semiconductor chip.We evaluate the signal quality of this nanophotonic device using hyperspectral-imaging technology,and we compare its performance with that of a standard prism-based commercial system.Two standard biochemical agents are employed for this characterization study:bovine serum albumin and inactivated influenza A virus.Time resolutions of data acquisition varying between 360 and 2.2 s are presented,yielding 2.731025–1.531026 RIU resolutions,respectively.

High-sensitivity integrated devices based on surface plasmon resonance for sensing applications

A metallic nanostructured array that scatters radiation toward a thin metallic layer generates surface plasmon resonances for normally incident light. The location of the minimum of the spectral reflectivity serves to detect changes in the index of refraction of the medium under analysis. The normal incidence operation eases its integration with optical fibers. The geometry of the arrangement and the material selection are changed to optimize some performance parameters as sensitivity, figure of merit, field enhancement, and spectral width. This optimization takes into account the feasibility of the fabrication. The evaluated results of sensitivity(1020 nm/RIU)and figure of merit(614 RIU^(-1)) are competitive with those previously reported.

High-Q micro-ring resonators and grating couplers for silicon-on-insulator integrated photonic circuits

An ultra-small integrated photonic circuit has been proposed,which incorporates a high-quality-factor passive micro-ring resonator（MR） linked to a vertical grating coupler on a standard silicon-on-insulator（SOI） substrate.The experimental results demonstrate that the MR propagation loss is 0.532 dB/cm with a 10μm radius ring resonator,the intrinsic quality factor is as high as 202.000,the waveguide grating wavelength response curve is a 1 dB bandwidth of 40 nm at 1540 nm telecommunication wavelengths,and the measured fiber-to-fiber coupling loss is 10 dB.Furthermore,the resonator wavelength temperature dependence of the 450 nm wide micro-ring resonator is 54.1 pm/℃.Such vertical grating coupler and low loss MR-integrated components greatly promote a key element in biosensors and high-speed interconnect communication applications.

High-bandwidth nanopositioning via active control of system resonance

Typically,the achievable positioning bandwidth for piezo-actuated nanopositioners is severely limited by the first,lightly-damped resonance.To overcome this issue,a variety of open-and closed-loop control techniques that commonly combine damping and tracking actions,have been reported in literature.However,in almost all these cases,the achievable closed-loop bandwidth is still limited by the original open-loop resonant frequency of the respective positioning axis.Shifting this resonance to a higher frequency would undoubtedly result in a wider bandwidth.However,such a shift typically entails a major mechanical redesign of the nanopositioner.The integral resonant control(IRC)has been reported earlier to demonstrate the significant performance enhancement,robustness to parameter uncertainty,gua-ranteed stability and design flexibility it affords.To further exploit the IRC scheme’s capabilities,this paper presents a method of actively shifting the resonant frequency of a nanopositioner’s axis,thereby delivering a wider closed-loop positioning bandwidth when controlled with the IRC scheme.The IRC damping control is augmented with a standard integral tracking controller to improve positioning accuracy.And both damping and tracking control parameters are analytically optimized to result in a Butterworth Filter mimicking pole-placement—maximally flat passband response.Experiments are conducted on a nanopositioner’s axis with an open-loop resonance at 508 Hz.It is shown that by employing the active resonance shifting,the closed-loop positioning bandwidth is increased from 73 to 576 Hz.Consequently,the root-mean-square tracking errors for a 100 Hz triangular trajectory are reduced by 93%.

SOLVABILITY FOR FRACTIONAL FUNCTIONAL DIFFERENTIAL EQUATION BOUNDARY VALUE PROBLEMS AT RESONANCE

The paper deals a fractional functional boundary value problems with integral boundary conditions. Besed on the coincidence degree theory, some existence criteria of solutions at resonance are established.