A rigorous design method for antiresonant reflecting opticalwaveguides

A new iteration technique has been proposed for calculating exact antiresonant values of cladding layer thicknesses in antiresonant reflecting optical waveguides (ARROW's). This technique enables design of ARROW waveguides with core layers incorporating sophisticated multilayer systems, where the approximate analytical formulas cannot be applied     

Polarization splitter based on antiresonant reflecting opticalwaveguides

We propose the first polarization splitter based on antiresonant optical waveguides (ARROW's). The three air core structure is built up of two moveable outer cladding layers and two fixed inner cladding layers. The moveability of both outer cladding layers makes micromechanical switching of the polarized light between two output channels possible. The polarization discrimination is realized through thin metal films deposited on the outermost surfaces of the outer cladding layers. The extinction ratios of channels 1 and 3 as a function of the thickness of all cladding layers are calculated. We found that for extinction ratios below -20 dB thickness fluctuations smaller than ±15 mm are allowed     

A novel hybrid coupler based on antiresonant reflecting opticalwaveguides

A novel hybrid coupler based on the antiresonant reflecting optical waveguides (ARROWs) is presented. This device consists of two parallel antiresonant reflecting optical waveguides with a tapered outermost cladding layer. Such a device can provide advantageous features of low radiation loss, low crosstalk at the output end, and compatible core dimensions and indexes with single-mode optical fibers. The staircase approximation and the eigenmode expansion analysis are used to analyze and optimize this device. In our design on a Si-substrate, radiation losses below 0.38 dB and extinction ratios below -20 dB for two waveguide channels are achieved. The beam propagation method (BPM) is also used to verify our design and analysis results     

Optimized silicon antiresonant reflecting optical waveguides forsensing applications

The development of an evanescent field sensor with an integrated Mach-Zehnder interferometric (MZI) configuration requires the fabrication of optical waveguides with two main characteristics: (1) monomode behavior and (2) high surface sensitivity for sensing biomolecular interactions in a direct way (without labels). In this paper, we present an experimental study for the optimization of the different parameters of the waveguides that will be the basis of a highly sensitive optical sensor. After optimization, an MZI sensor has been fabricated and some sensing applications are shown. The designed waveguides are based on antiresonant reflecting optical waveguide (ARROW) structures and are fabricated with standard silicon technology     

Scattering loss of antiresonant reflecting optical waveguides

The scattering loss of two-dimensional antiresonant reflecting optical waveguides (ARROW) and of ARROW-B, which has a similar structure to ARROW and less polarization dependence, are analyzed by the first-order perturbation theory. Calculated results are compared with those of conventional three layer waveguides. Optimum design for the reduction of scattering loss of these ARROW-type waveguides is discussed. It was found that the scattering loss of ARROW-type waveguides is no larger than that of a conventional waveguide having a relative refractive-index difference, Δ of 2.5%, despite each interface of ARROW-type waveguides having a large Δ, normally larger than 20%. The optimum design for the reduction of essential radiation loss of ARROW is also optimum for the reduction of scattering loss     

Comprehensive above-threshold analysis of antiresonant reflecting optical waveguide edge-emitting diode laser

A three-dimensional (3-D) above-threshold analysis has been performed for laterally antiguided laser structures of the antiresonant-reflecting-optical-waveguide type, of relatively large core width (/spl sim/ 10 /spl mu/m), for high-power, single-spatial-mode operation. A 3-D numerical code has been developed, which takes into account carrier diffusion in the quantum well as well as edge radiation losses. The laser characteristics are calculated as functions of the above-threshold drive level. Within the simulation, 3-5 higher order optical modes on a "frozen background" are computed by the Arnoldi algorithm. Because of the nonuniform gain saturation of the lasing mode, the modal gains for higher order modes increase with the drive current due to increasing overlap of their fields with the two-dimensional gain distribution. The onset of threshold for higher order modes puts an upper limit on the range for stable single-mode operation. The above-threshold analysis is done for various values of the width of the reflector region, below and above the lateral-antiresonance condition. It is found that the maximum intermodal discrimination, which in turn provides the maximum single-mode power, is obtained when the reflector-region width is /spl sim/25 % larger that its value at antiresonance. Then, for 10-/spl mu/m-core devices, stable, single-mode operation is found to occur to drive levels as high as 41 /spl times/ threshold, with single-mode output powers as high as 1.45 W.     

Two-dimensional numerical analysis of a silicon magnetic field sensor

We present two-dimensional numerical solutions of the coupled, nonlinear, partial differential equations governing the electric potential, carrier drift, diffusion, generation, and recombination in a finite semiconductor slab in the presence of a magnetic field. This enables device modeling for general geometries, doping levels, and injection conditions, where the effect of the magnetic field cannot be expressed simply in terms of Hall voltage, Lorentz deflection, or magnetoconcentration.     

Suppression of polarization switching in birefringent antiresonant reflecting optical waveguide vertical-cavity surface-emitting lasers

Influence of birefringence on the multimode operation of antiresonant reflecting optical waveguide (ARROW) vertical-cavity surface-emitting lasers (VCSELs) is analyzed. It can be shown that polarization switching is mainly due to thermal lensing effects. Hence, a new design rule is proposed to optimize the dimensions of ARROW for the suppression of polarization switching. Using the optimized design, the maximum single-polarization output power of VCSELs can be tripled. In addition, it is shown that the performance of the optimized ARROW VCSELs will not be deteriorated by the uncertainty of birefringence.     

MEMS magnetic field sensor based on silicon bridge structure

A MEMS piezoresistive magnetic field sensor based on a silicon bridge structure has been simulated and tested.The sensor consists of a silicon sensitivity diaphragm embedded with a piezoresistive Wheatstone bridge,and a ferromagnetic magnet adhered to the sensitivity diaphragm.When the sensor is subjected to an external magnetic field, the magnetic force bends the silicon sensitivity diaphragm,producing stress and resistors change of the Wheatstone bridge and the output voltage of the sensor.Good agreeme...     

基于硅桥结构的MEMS磁场传感器

提出了一种基于硅桥结构的MEMS磁场传感器结构。其结构由制作在硅桥敏感膜表面的惠斯通电桥和在膜中间沾上铁磁体制成。当传感器处于磁场中时,铁磁体在外磁场中磁化产生磁力,磁力会使硅敏感膜弯曲从而引起压阻改变进而使惠斯通电桥产生电压输出以达到测量磁场的目的。文章通过有限元软件仿真对铁磁体的尺寸进行了优化。实验结果和理论结果较接近。实验测得该传感器最大灵敏度为48mV/T,分辨率为160μT,该传感器可以用来进行强磁场的测量。实验结果结果表明:传感器的重复性和动态响应时间分别约为0.66%和150ms。     

Compensation for surface contamination in a D-fiber evanescent wavemethane sensor

The effects of surface contamination on the performance of a D-fiber evanescent wave methane sensor are discussed. Contamination on the flat surface of the D-fiber will modify both the scale factor of the methane detection system and the birefringence of the D-fiber. The birefringence variation can be monitored and used to compensate for the scale factor variation, through one of the two compensation models which will be described in the text. The models are found to be fairly accurate, and for the D-fiber used in our experimental tests, the maximum relative error for scale factor correction is about ±5%, for both models     

An integrated silicon magnetic field sensor using the magnetodiode principle

We report a novel integrated magnetic field sensitive device. Its structure is reminiscent of the bipolar transistor, but its operation is essentially that of a magnetodiode: a reverse-biased p-n (collector) junction plays a role similar to that of the high recombining surface of classical magnetodiodes. The device can be manufactured in standard bulk CMOS or bipolar technology. Sensitivity up to 25 V/T at 10-mA current is achieved. Voltage-current characteristics shows saturation and negative resistance regions, which are explained by JFET and UJT effects, respectively.     

Nonlinear analysis of a CMOS integrated silicon pressure sensor

This paper reports theoretical and experimental results of analysis on the nonlinear characteristics of a CMOS integrated pressure sensor with a square silicon diaphragm. It is shown that nonlinearity is caused by both the large diaphragm deflection and the nonlinear piezoresistance of the resistors. The optimum layout for the piezoresistors to minimize their nonlinearity is also shown. The measured nonlinearity for the fabricated device agrees well quantitatively with the numerically analyzed nonlinearity.     

U型微弱梯度磁场检测传感器设计及应用

本文就U型微弱梯度磁场检测传感器的设计原理、结构、应用领域等进行了较为全面的叙述,并与其他检测方法在同一标准磁场条件下在测量灵敏度、重复性等方面进行了比较,结果表明各项指标均优于其他传感器。该传感器用于均匀变化磁场中测量非均匀直流梯度弱磁场,检测微弱磁场的变化,在实现微弱磁场的过零检测中具有独特性,且便于实现自动化测量,具有良好应用和开发空间。该传感器在开磁路软磁矫顽力测量中得到很好的应用。     

新型反谐振反射光波导传感器的研究

为了寻找到性能更好、灵敏度更高的光波导传感器,在传统反谐振反射光波导结构的基础之上,提出了一种新型反谐振反射光波导传感器,对其反射率和传输损耗进行了模拟,并计算了它的灵敏度.结果表明,与传统表面均匀传感型反谐振反射光波导传感器相比,新型传感器直接将待测的样品作为波导层并且采用了周期结构的反共振层,使大部分光束集中在样品中传播,从而降低了传输损耗,提高了传感器的灵敏度,为波导传感器的制作提供了一定的数值参考.     

截止波导带通滤波器的设计

简述了截止波导带通滤波器的基本设计原理,并实现了一款小型化的超窄带带通滤波器。中心频率为3.65 GHz,带宽为30 MHz。体积仅为42 mm×11 mm×7.5 mm,带内插入损耗小于6 dB,带内反射小于-22 dB,阻带的衰减曲线相当陡峭。通过的实验证实了该方法的可行性和正确性。     

Design and analysis of asynchronous wakeup for wireless sensor networks

In wireless sensor networks, scheduling the sleep duration of each node is one of the key elements for controlling critical performance metrics such as energy consumption and latency. Since the wakeup interval is a primary parameter for determining the sleeping schedule, how to tune the wakeup interval is crucial for the overall network performance. In this paper, we present an effective framework for tuning asynchronous wakeup intervals of IEEE 802.15.4 sensor networks from the energy consumption viewpoint. First, we derive an energy consumption model of each node as an explicit function of the wakeup interval, and empirically validate the derived model. Second, based on the proposed model, we formulate the problem of tuning the wakeup interval with the following two objectives: to minimize total energy consumption and to maximize network lifetime. We show that these two problems can be optimally solved by an iterative algorithm with global information by virtue of the convexity of the problem structure. Finally, as practical solutions, we further propose heuristic optimization algorithms that only exploit local information. In order to develop heuristic algorithms, we propose two broadcasting schemes, which are entitled as maximum wakeup interval broadcasting and efficient local maximum broadcasting. These broadcasting algorithms enable nodes in the network to have heterogeneous wakeup intervals.     

Review of finite element methods for microwave and opticalwaveguides

The authors review the application of the finite element method to analysis of waveguide problems. They discuss the significance of different variational formulations, the modeling of the infinite domain of open-boundary waveguides, techniques to avoid spurious solutions, and matrix solution techniques. They briefly refer to the application of these techniques to waveguides containing nonlinear materials and to three-dimensional problems     

Design and analysis of an optical waveguide tap for silicon CMOScircuits

A compact low-loss optical tap technology is critical for the incorporation of optical interconnects into mainstream complementary metal-oxide-semiconductor (CMOS) processes. For this work, an effort has been made to establish an optimal integrated optical tap design in terms of optical loss, bandwidth, economy, and process compatibility with multimetal layer CMOS circuits. A new device, which is based on a variation of the multimode interference effect, has been found to be especially promising. Two-dimensional (2-D) and three-dimensional (3-D) simulation results show low excess optical loss (<0.1 dB) for the design, and a nominal 40% (2.2 dB) optical coupling into the CMOS circuitry over a wide range of guide to substrate distances. Simulated tap devices are on the order of 15 [tin in length. Polymer waveguide materials are targeted for tap fabrication due to planarization properties, low cost, broad index control, and poling abilities for modulation-tuning functions. Low-cost silicon CMOS-based processing makes the new tap technology especially suitable for computer multichip module and board level interconnects, as well as for metro fiber to the home and desk telecommunications applications     

基于光纤倏逝波传感器的磷酸根离子检测

提出了利用光纤倏逝波传感器通过光吸收方法来测量溶液中磷酸根离子浓度的新方法。将通信用标准单模光纤（SMF）局部腐蚀到接近芯层后放入不同浓度的磷钼蓝溶液中,当以磷钼蓝光吸收峰值为探测光波长时,光纤表面的倏逝波会部分被溶液吸收,通过测量光纤输出光强来计算溶液中的磷酸根离子浓度。实验结果表明,磷钼蓝溶液中磷浓度为0．04～O...