A novel structure of silicon-on-insulator microring biosensor based on Young's two-slit interference and its simulation

A novel silicon-on-insulator microring biosensor based on Young’s twoslit interference has been demonstrated. The transducer signal from electric field intensity distribution on the interference screen is given by using the transfer matrix method(TMM) and two-slit interference principle.The result shows that the structure we propose is advantageous for sensing as the interference pattern is very sensitive to the ambient refractive index around the microring.A small perturbation in refractive index around the microring△n_c will result in a notable shift of destructive interference points(DIPs) on the interference screen.By detecting the shift of the DIPs,the ambient refractive index change can be obtained.     

微环谐振器的弯曲损耗

通过解弯曲波导的正规模的方法,从理论上分析了微环谐振器的弯曲损耗与微环的直径、宽度和厚度间的对应关系,给出了微环谐振器的弯曲损耗与微环芯和周围介质折射率对比间的关系.将上述的计算结果与保角变换方法的计算结果进行了比较.设计了微环谐振器的特征参数.     

Polarization-Insensitive Ultrasmall Microring Resonator Design Based on Optimized Si Sandwich Nanowires

Bent Si sandwich nanowires are used and optimized to obtain an ultrasmall polarization-insensitive microring resonator (MRR). The used Si sandwich nanowire has a low refractive index layer between two Si layers with high refractive indexes. By optimizing the refractive index and thickness of the sandwiched layer, the bent Si sandwich nanowire becomes nonbirefringent theoretically. The designed nonbirefringent nanowire has a relatively good fabrication tolerance. By using such a nonbirefringent bent Si sandwich nanowire, an ultrasmall polarization-insensitive MRR is designed.     

Design and modeling of waveguide-coupled single-mode microringresonators

We discuss a first-order design tool for waveguide-coupled microring resonators based on an approximate solution of the wave propagation in a microring waveguide with micron-size radius of curvature and a large lateral index contrast. The model makes use of the conformal transformation method and a linear approximation of the refractive index profile, and takes into account the effect of waveguide thickness, dispersion, and diffraction. Based on this model, we develop general design rules for the major physical characteristics of a waveguide-coupled microring resonator, including the resonance wavelength, the free spectral range, the coupling ratio, the bending radiation loss and the substrate leakage loss. In addition, the physical model provides leads to alternative coupling designs. We present two examples, one using a phase-matching parallel waveguide with a smaller width than the ring waveguide, and the other using a vertical coupling structure. Both these designs significantly increase the coupling length and reduce or eliminate the dependence on a narrow air gap in a waveguide coupled microring resonator     

Temperature insensitive vertically coupled microring resonatoradd/drop filters by means of a polymer overlay

The temperature dependence of vertically coupled glass microring resonator add/drop filters is investigated. Measurements show that the passband of the air-clad microring resonator filter increases with temperature at a rate of 0.0137 mm/°C. Using a PMMA-TFMA polymer that has an opposite refractive index temperature gradient than glass as the overlay of the microring resonator, the temperature dependence of the filter is compensated to -0.0025 nm/°C in the operation range of 25°C to 55°C     

基于硅基微环谐振器的折射率传感研究综述

片上折射率传感在安全检查、环境监测、健康诊断和食品监督等领域有着广阔的应用前景,基于硅基微环谐振器的折射率传感器具有微型化、集成化等优点,已成为当前研究的热点。文章首先对硅基微环谐振器的折射率传感探测原理进行了介绍,然后依据探测原理分类梳理了国内外硅基微环折射率传感的最新研究进展,并分析总结了不同传感探测原理的优缺点,最后讨论了现阶段硅基微环谐振器在折射率传感中存在的问题和未来的发展方向。     

基于狭缝波导的聚合物基微环折射率传感器研究

基于狭缝波导结构,设计了工作波长在890 nm的聚合物基微环。从折射率传感的角度详细分析了狭缝波导的模场特性。分析了波导高度、宽度及狭缝宽度对灵敏度的影响。传统的狭缝波导具有较高的弯曲损耗,这会影响微环谐振器的品质因子Q以及消光比。设计了非对称的狭缝结构,保证波导模式位于波导中央传输,降低弯曲损耗。为了条形波导与狭缝波导更好的耦合,设计了基于多模干涉结构的条形-狭缝波导模式转换器。仿真表明设计的微环谐振器的传感灵敏度达到109 nm/RIU。     

Wavelength trimming of a microring resonator filter by means of aUV sensitive polymer overlay

Trimming of the resonant wavelength of a vertically coupled glass microring resonator channel dropping filter with a photo-induced refractive index change in a dip coated polymer overlay is reported. In this letter, the glass microring resonator has a radius of 19 μm, a free-spectral range of 10 nm, and a Q value of 800. The maximum wavelength shift observed is 9 nm, which is yielded through an absolute bulk index change in the polymer of 0.044. Trimming is a continuous function of exposure time and dose     

腐蚀型FBG在非均匀液相介质下的数值响应特性

基于光波导理论和传输矩阵法,研究了光纤Bragg光栅(FBG)折射率传感器在非均匀液相介质下的响应特性。在数值计算中,分别考虑高折射率区(1.42～包层折射率)和低折射率区(1.33～1.36)两种情况,并假设非均匀液相介质的折射率分布为线性函数,仿真结果表明,FBG的反射谱特性强烈依赖于介质折射率分布函数的某些特征参数,比如折射率沿FBG轴向的分布梯度、折射率在FBG两端的差值。研究结果对FBG折射率传感器在生化传感中的应用具有一定意义。     

All-optical switching in a laterally coupled microring resonator by carrier injection

We demonstrate all-optical switching in a laterally coupled GaAs-AlGaAs microring resonator by carriers injections. The ring waveguide is optically pumped just above its bandgap energy, which results in a temporal tuning of the microring resonant wavelengths by the refractive index change due to the induced carriers. A switching window of 20 ps could be obtained and is only limited by the carrier recombination time. A switching energy of a few tens of picojoules per pulse is used and has resulted in a 1.2-nm wavelength shift of the microring resonance.     

Lightwave switching in semiconductor microring devices by free carrier injection

Using a conventional microwave photonic technique, we demonstrate lightwave switching in laterally coupled GaAs-AlGaAs microring resonators by free carrier injection. The ring waveguide is optically pumped just above its bandgap energy, which results in a temporal tuning of the microring resonant wavelengths by the refractive index change due to the induced free carriers. Both the transmission and the phase function of the resonators are investigated and used to demonstrate all-optical switching. The switching time, limited by surface recombination of carriers, is 20 ps. A switching energy of a few picojoules shifts the microring resonance by 1.2 nm.     

飞秒激光制备光纤微孔传感器

为了实现高精度、低成本的液体折射率测量,采用飞秒激光水辅助微加工技术,制备出一种基于微孔结构的单模光纤液体折射率传感器.研究了传感器的传输损耗与孔内液体折射率及微孔长度的关系,利用射线理论分析了传感的机理,讨论了温度对传感器性能的影响.结果表明,该传感器在折射率1.333～1.413区间具有良好的线性响应,灵敏度达到157.48dB/RIU,且不易受温度串扰.该传感器具有结构紧凑、制备简单、高灵敏度、温度不敏感和低成本等优点,在生物化学测量领域中有着广泛的应用前景.     

Goos-Hänchen shift as a probe in evanescent slab waveguide sensors

The present paper deals with three-layer planar waveguide optical sensor. Different from the conventional slab waveguide sensors in which the effective refractive index of the propagating mode is taken to be the probe for detection changes in the analyte refractive index, we adopt Goos-Hänchen (GH) shift as the sensing probe for the proposed sensor. We show that the GH shift is strongly dependent on the refractive index of the cladding, thus it is a good candidate for detection changes in the analyte refractive index. We present and study the sensitivity of the GH shift at the cladding-film and substrate-film interfaces. It is found that GH shift has a high sensitivity and can be used for versatile optical slab waveguide sensors.     

Micromachined thermally based CMOS microsensors

An integrated circuit (IC) approach to thermal microsensors is presented. The focus is on thermal sensors with on-chip bias and signal conditioning circuits made by industrial complementary metal-oxide-semiconductor (CMOS) IC technology in combination with post-CMOS micromachining or deposition techniques. CMOS materials and physical effects pertinent to thermal sensors are summarized together with basic structures used for microheaters, thermistors, thermocouples, thermal isolation, and heat sinks. As examples of sensors using temperature measurement, we present micromachined CMOS radiation sensors and thermal converters. Examples for sensors based on thermal actuation include thermal flow and pressure sensors, as well as thermally excited microresonators for position and chemical sensing. We also address sensors for the characterization of process-dependent thermal properties of CMOS materials, such as thermal conductivity, Seebeck coefficient, and heat capacity, whose knowledge is indispensable for thermal sensor design. Last, two complete packaged microsystems-a thermoelectric air-flow sensor and a thermoelectric infrared intrusion detector-are reported as demonstrators     

Single-Photon Response and Spectroscopy of a Photonic Molecule Based on Diamond Microrings

The optical properties of a photonic molecule consisting of three diamond microring cavities are theoretically investigated. The probability of single-photon excitation (optical response) of a photonic molecule by a weak laser field in the steady-state mode with regard to the dissipative effects is calculated using the model analogous to the tight binding approximation. It is shown that the spectrum can be fine tuned by depositing additional layers onto the photonic-molecule surface. The dependences of the wavelength of the mode corresponding to the zero-phonon optical transition in the NV center on the thickness of these layers and refractive index of their material are established. The NV center localized in the electromagnetic field antinode effectively interacts with the photonic molecule eigenmode, which can be observed as anticrossing points in the dependences of the optical response of the system on exciting laser and transition frequencies.     

基于表面等离子体共振的高灵敏度光纤微流控芯片

设计了一种可嵌入基于表面等离子体共振(SPR)光纤传感器的微流控芯片,可用于溶液浓度的测量。采用具有良好化学惰性的有机聚合材料聚二甲基硅氧烷(PDMS)作为芯片主体的制作材料,在芯片中微流控通道内采用镀有60 nm金膜的多模光纤-光子晶体光纤-多模光纤(MMF-PCF-MMF)传感结构来激发SPR效应。当注入微流体通道的溶液浓度发生变化时,由于光纤传感部分外部折射率的变化引起SPR谐振谷移动,故该芯片可用于测量溶液浓度。本芯片微流控通道直径为0.2 mm,最高检测灵敏度可达8240.6 nm/RIU,具有便于实时测量、高灵敏度、高可靠性、溶液用量少等特点。     

高深宽比金属光栅制备及中红外波段传感特性

利用纳米压印结合溅射和反应离子刻蚀工艺制备了具有高深宽比的金光栅,使用傅里叶变换红外光谱仪测得了反射谱线.测量结果显示,只在p偏振光垂直于光栅矢量方向入射条件下才存在共振反射峰,证明了“伪表面等离子体激元波”的存在.基于严格耦合波分析理论计算了金属光栅的反射率,研究了其作为中红外波段波长调制型表面等离子体共振传感器的可行性.数值计算表明负级次衍射光波对应的共振反射峰的移动能获得较高的波长灵敏度.对于深宽比为10的金光栅结构,+1级次和-3级次衍射光波对应的波长灵敏度分别为1600 nm/RIU和5000 nm/RIU,品质因子分别为20 RIU-1和60RIU-1.     

飞秒写制长周期光纤光栅的液体浓度测量实验研究

利用逐点写入法在去涂敷层的普通单模通信光纤中直接写入了长周期光纤光栅(LPFG),实验获得的LPFG在C波段的谐振波长1 538.8nm,衰减强度达10.63dB。其氯化钠和蔗糖溶液浓度传感特性实验表明,随着盐溶液浓度的增大,LPFG的谐振波长向左线性漂移,盐浓度每增加1%,波长向左漂移约0.05nm;随着糖溶液浓度从0%增大为50%,LPFG的谐振波长向左非线性漂移量高达约8nm。实验结果表明:飞秒激光逐点写入法操作简单,容易控制诱导的周期性折射率微扰在纤芯和或包层的位置,从而制备出对低浓度液体敏感的LPFG化学传感器;同时飞秒激光写制的LPFG具有较高的外界环境灵敏度,有望用在化学浓度传感中。     

单直波导光学环腔器件的Q值研究

为实现高品质因数Q值的光学环腔器件,采用耦合模理论,仿真得出单直波导光学环腔器件的Q值与自耦合系数的关系曲线.以Si3N4为材料,采用与CMOS工艺相兼容的技术制备了波导宽度为2μm,半径为200μm的Si3N4单直波导光学环腔器件.在相同的制备工艺下,同一芯片中不同光学环腔的传输系数相同,通过设计器件中环腔与直波导的...     

Microchanneled Chirped Fiber Bragg Grating Formed by Femtosecond Laser-Aided Chemical Etching for Refractive Index and Temperature Measurements

In this work, a microchanneled chirped fiber Bragg grating (MCFBG) is proposed and fabricated through the femtosecond laser-assisted chemical etching. The microchannel ( $sim$550 $mu$ m) gives access to the external index liquid, thus inducing refractive index (RI) sensitivity to the structure. In the experiment, the transmission bands induced by the reduced effective index in the microchannel region were used to sense the surrounding RI and temperature changes. The experimental results show good agreement with the theoretical analysis. The proposed MCFBG offers enhanced RI sensitivity without degrading the robustness of the device showing good application potential as bio-chemical sensors.