Tunable optical filter based on Sagnac phase-shift using single optical ring resonator

In this paper, a single optical ring resonator connected to a Sagnac loop is used to demonstrate theoretically a novel narrow band optical filter response that is based on Sagnac phase-shift Δφ. The given filter structure permits the Sagnac rotation to control the filter response. It is shown that by changing the Sagnac rotation rate, we can tune the filter response for desired bandwidths. To increase the wavelength selectivity of the filter, the Sagnac phase-shift should be as small as possible that is limited by the loop length. For Δφ=0.1 rad, the obtained FWHM is 2.63 MHz for tuning loop length of 2 m. The simulation response agrees fairly with the recently reported experimental result.     

Dual-band optical filter based on a single microdisk resonator

We propose and experimentally demonstrate a dual-band optical filter based on a single microdisk resonator. An analytical model is built based on the transfer matrix method and is applied to simulate the properties of such a device. Competition and interference of the dual modes in the resonator lead to dual-band filtering with high isolation. As the finite-difference time-domain simulation illustrates, two low-order resonant modes can be effectively triggered by optimizing the waveguide width and spacing gap between the compact resonator and waveguides. In experiment, a double side-coupled microdisk resonator was fabricated on a nanophotonic silicon-on-insulator platform, and dual-band bandpass filtering is realized with an optical isolation higher than 20 dB and an insertion loss lower than 2 dB. The experimental results agree well with our modeling results.     

平面环形谐振腔微光学陀螺结构设计与优化

提出具有高群有效折射率的双环级联作为核心元件的谐振式平面光波导陀螺结构, 基于光学Sagnac原理得到了双微环耦合谐振式光学陀螺理论灵敏度与群有效折射率的一般表达式和双环与单环陀螺系统的灵敏度关系, 并由耦合模理论方法得到了双环系统耦合器的两个透射系数对应的群有效折射率变化情况. 在环腔半径R₁=R₂=100 μm、环腔传输损耗系数t₁=t₂=0.95的情况下, 针对环与环之间耦合器和环与波导之间耦合器透射系数对群有效折射率的不同影响, 得到了最大群有效折射率的产生条件. 采用文中参数(R=100 μm, t=0.95)计算的单环谐振式陀螺灵敏度为(10⁴-10⁵)°/h, 而双环级联谐振系统理论灵敏度能够达到10 °/h. 该研究对微环耦合谐振腔在角速度检测上的应用有重要的意义.     

A dual-band polarization insensitive metamaterial absorber with split ring resonator

A dual-band polarization insensitive absorber has been proposed . Unlike the previous dual band absorber composed of composite structures, only one square metal ring with a slit at the middle of each side can be used to achieve the dual-band absorption. The calculated results show two distinct absorption peaks of 0.96 at 10 GHz and 0.99 at 20 GHz. In addition, the positions of the two peaks are strongly influenced by the width of the slit (g). More importantly, the absorptions of the two peaks keep higher than 0.9 while g changing. The dual-band absorber may have many potential applications in scientific and technological areas because of its excellent absorption characteristics and concise structure.     

Optical multiplexing of microcavity sensors based on a fiber laser

A new principle of creating multiplex systems of active oscillator microcavity fiber-optic sensors is considered. The results of experimental studies of a multiplex system with two measuring channels are presented.     

Vertical input optical ring resonator with differential operation for optical sensor

A novel waveguide ring resonator optical sensor with two resonant wavelength channels is proposed for a refractive index measurement of a test sample placed on the sensor substrate and its performance characteristics are investigated analytically and numerically. The waveguide device consists of a ring resonator, a split-ring-shaped loop waveguide, and a vertical input/output grating coupler, in which the loop waveguide acts as an additional resonator and provides another output wavelength channel of the sensor. The differential detection between the two wavelength channels enables the highly sensitive detection with temperature compensation. A numerical simulation based on a finite difference time domain (FDTD) method shows that a precise index change detection with a resolution of 10⁻⁶ can be achieved using of the proposed device.     

Chaotic dynamics of active optical fiber ring resonator with optical injection

We experimentally obtain the route from period doubling to chaos in an active optical fiber ring resonator （AOFRR） with optical injection. The results show that the AOFRR is sensitive to external optical injection and demonstrate various dynamic characteristics. Meanwhile, the change of the injection strength can cause the output of the AOFRR to become periodic or chaotic. It can be confirmed that all the dynamic characteristics of the system are due to the interaction of the semiconductor laser with the erbium-doped fiber amplifier （EDFA）.     

A spectacles-shaped optical fibre ring resonator with two couplers

A theoretical study of a novel spectacles-shaped optical fibre ring resonator with double couplers has been carried out. The circulating, transmitted and reflected output fields and intensities have been computed and presented as graphs. The characteristics, advantages and possible applications of this ring resonator are discussed.     

Observation of photoacoustic/photothermal effect with a liquid-core optical ring resonator

Photothermal/photoacoustic(PT/PA) spectroscopy provides useful knowledge about optical absorption, as well as the thermal and acoustical properties of a liquid sample. For microfluidic biosensing and bioanalysis where an extremely small volume of liquid sample is encapsulated, simultaneous PT/PA detection remains a challenge. In this work, we present a new optofluidic device based on a liquid-core optical ring resonator(LCORR) for the investigation of PT and PA effects in fluid samples. A focused 532 nm pulsed light optically heats the absorptive fluid in a capillary to locally create a transient temperature rise, as well as acoustic waves. A1550 nm CW laser light is quadrature-locked to detect the resonance spectrum shift of the LCORR and study thermal diffusion and acoustic wave propagation in the capillary. This modality provides an optofluidic investigative platform for biological/biochemical sensing and spectroscopy.     

Coupled frequency-doubling optoelectronic oscillator based on polarization modulation and polarization multiplexing

A coupled frequency-doubling optoelectronic oscillator (OEO) is proposed and experimentally demonstrated, which is constructed based on the perfect combination of polarization modulation and polarization multiplexing. A fundamental microwave signal at 9.95 GHz or a frequency-doubled microwave signal at 19.9 GHz is generated with a wavelength-independent sidemode-suppression ratio (SMSR) as high as 78 dB obtained. The phase noise of the generated 19.9-GHz signal is ? 103.45 dBc/Hz at 10-kHz frequency offset, indicating a good short-term stability. The proposed scheme is simple and flexible, which can find applications in radars and wireless communications.     

利用EastFDTD研究基于金属谐振环的新型滤波器

基于金属表面等离子体空间局域非辐射特性,利用电磁场仿真软件EastFDTD和时域有限差分法(FDTD)设计了一种新型滤波器。通过金属谐振环结构中内径分别为175 nm和145 nm金属环对谐振波长的调控作用,在中红外波段不同端口实现了分别输出1.85μm和1.58μm波长的信号,相邻端口之间的串扰可以达到-19 dB,同时输出端口的结构尺寸仅为50 nm。计算结果表明该新型滤波器在滤波性能和器件小型化集成化方面均具有显著优势。     

Evaluation of single virus detection through optical biosensor based on microsphere resonator

Shift of resonance frequency in microsphere optical resonator due to attachment of a desirable particle is obtained. Our 3-D finite element numerical method (FEM) simulations’ results show the path of light through microsphere and its variation due to attachment of particle. It is apparent that after attachment of particle to microsphere's surface, light is inclined to pass through the particle. Subsequently, the path of light becomes longer than previous. Because of this phenomenon, the resonance wavelength shifts to longer wavelengths. It is shown that microsphere optical resonator is a prominent biosensor for single virus detection since we applied characteristics of virus for particle in our simulations. Response of this biosensor depends on the characteristics of particle like its radius as we show in this article. Transmission spectrum of fiber which reveals a selected resonance frequency, have been studied in the frequency range of 106.3 to 107 THz under three different sizes of particles. The results show that the amount of frequency shift rises by enhancement of particle's size.     

Generalized optical filters using a nonlinear micro ring resonator system

We present the interesting results of nonlinear behaviors of a soliton pulse within a nonlinear micro ring resonator system, where the optical filter characteristics in terms of frequency, wavelength and time can be functioned by using the chaotic filter within the micro ring resonator system. There are three forms of applications using the chaotic soliton behaviors and optical filter characteristics presented. Firstly, the simultaneous up-link and down-link frequency bands can be filtered and the required frequency bands obtained. Secondly, we propose the simple system of an extremely narrow light pulse generation over the spectrum range, where the required wavelengths can be filtered and obtained. Finally, a simple system of fast light generation by using a soliton pulse circulating in the integrated micro ring devices is proposed. Using such a system, an attosecond pulse and beyond can be easily filtered and obtained.     

基于偏振编码的副载波复用量子密钥分发研究

提出了一种采用相位合成偏振态编码的副载波复用量子密钥分发方案,该方案在不增加系统设备的前提下允许多路量子密钥通过并行的边带信道同时进行分发．每一个边带的偏振态可通过控制副载波的相位随机且独立地合成．该方案允许量子密钥系统的成钥率成倍的增加．仿真实验证明,通过调整每个副载波相位能够理想地调整和控制边带的偏振态．     

An ultrathin transparent metamaterial polarization transformer based on a twist-split-ring resonator

In this paper, an ultrathin transparent metamaterial polarization transformer using a circular twist-split-ring resonator (TSRR) was proposed and investigated experimentally and numerically. The experimental and simulated results exhibit an asymmetric transmission only for forward and backward propagating linearly polarized waves. An incident linearly polarized wave can convert its polarization nearly completely to the cross direction after transmission under certain conditions. The simulated spatial evolution of the electric field further indicates that the twist structure functions as a perfect polarization transformer at certain frequencies.     

Transmission of high-data-rate optical signals through a micrometer-scale silicon ring resonator

The effects of a micrometer-scale silicon ring resonator with a FWHM of 0.078 nm (9.6 GHz) on a nonreturn to zero amplitude-modulated optical signal with a modulation rate of 10 Gbps are experimentally investigated. By transmitting the optical signal through the device, significant spectral distortion and side band attenuation is introduced, as characterized by amplitude Bode plots, and a power penalty of 0.8 dB is observed. Carrier wavelengths within the transmission resonance, but detuned from the center wavelength, are investigated as well. Numerical simulations further support the experimental results.     

Design theory of high-Q optical ring resonator with asymmetric three-layered dielectrics

An optical ring resonator with asymmetric three-layered dielectrics is shown to have an anomalously highQ-factor compared with the conventional symmetric three-layered ring resonator by several orders of magnitude for suitably chosen parameters. A new leaky mode which can propagate on the asymmetric structure is found having an extremely small attenuation loss near the cut-off frequency of the guided mode, but which does not exist in the symmetric structure. Optimum values of the normalized frequency for a single-mode operation to suppress the undesired leaky modes are discussed. It is also shown that the size of the ring resonator using the asymmetric structure can be reduced considerably from that of the ordinary symmetric resonator.     

An advanced EPR stopped-flow apparatus based on a dielectric ring resonator

A novel EPR stopped-flow accessory is described which allows time-dependent cw-EPR measurements of rate constants of reactions involving paramagnetic species after rapid mixing of two liquid reagents. The EPR stopped-flow design represents a state-of-the-art, computer controlled fluid driving system, a miniresonant EPR structure with an integrated small ball mixer, and a stopping valve. The X-band EPR detection system is an improved version of that reported by Sienkiewicz et al. [Rev. Sci. Instr. 65 (1994) 68], and utilizes a resonator with two stacked ceramic dielectric rings separated by a variable spacer. The resonator with the mode TE(H)011 is tailored particularly for conditions of fast flowing and rapidly stopped aqueous solutions, and for a high time resolution. The short distance between the ball mixer and the small EPR active volume (1.8 microl) yields a measured dead time of 330 micros. A compact assembly of all parts results in minimization of disturbing microphonics. The computer controlled driving system from BioLogic with two independent stepping motors was optimized for EPR stopped-flow with a hard-stop valve. Performance tests on the EPR spectrometer ESP 300E from BRUKER using redox reactions of nitroxide radicals revealed the EPR stopped-flow accessory as an advanced, versatile, and reliable instrument with high reproducibility.     

Photonic microwave reconfigurable filter based on a tunable polymeric ring resonator

An integrated photonic microwave reconfigurable filter was proposed and realized incorporating a tunable polymeric ring resonator. Its passband could be shaped electrically by shifting the resonant peaks of the resonator via the thermo-optic effect. As for the achieved performance, the center frequency was 20 GHz, the extinction ratio ∼15 dB, the bandwidth 2 GHz, and the corresponding quality factor 10. The microwave output within the passband was varied efficiently by ∼27 dB with the rate of ∼6.7 dB/mW, while the wavelength tuning rate of the resonator was −0.02 nm/mW.