Microstrip directional coupler with flat coupling and high isolation

Based on the open-circuited slotline to realise capacitive compensation, a microstrip directional coupler with high isolation is investigated. Meanwhile, by adding external matching networks at the input/output ports, bandwidth is enhanced and a flat coupling is obtained. Centred at 2.4 GHz, a 3 dB directional coupler is designed, fabricated and examined. Both simulated results and measured data are presented, and good agreement between them is observed     

Microstrip directional coupler with nearly ideal TEM coupler performance

A meandered parallel coupled-line structure is proposed to achieve high directivity within a wide bandwidth. By properly increasing the meandered parallel coupled-line sections, the high-directivity bandwidth becomes much wider. An example coupler is fabricated to verify the theory. More than 50 dB of isolation is achieved over a bandwidth of zero to twice centre frequency.     

应用交指电容加载环谐振器的微带带阻滤波器

提出了一种交指电容加载环谐振器(IDCLLR),与同尺寸的开环谐振器(SRR)相比,具有更多的设计参数、更低的谐振频率和更大的动态范围,因而使得设计更加灵活、也更适于器件小型化.随后提出两种基于IDCLLR的亚波长微带带阻滤波器结构:第一种是由一对IDCLLR磁耦合到50欧姆微带传输线构成的滤波器,获得0.39%(-10 dB)的窄的阻带;第二种是由一个IDCLLR磁耦合到U形微带传输线中构成的滤波器,由于增强耦合而获得2.4%的较宽且深的阻带.文中给出了它们的全波仿真和测试结果.     

Proposed semiconductor narrow-band wavelength filter using directional coupler

A GaInAsP/InP waveguide narrow-band wavelength filter is proposed and analysed. The proposed wavelength filter is based on an asymmetric semiconductor directional coupler having a step-index waveguide and a double clad waveguide. It is numerically shown that a bandwidth as narrow as 5.4 nm is feasible for 1.3 mm long devices at a 1.53 mu m centre wavelength.<>     

Design of rectangular directional coupler using simple numericalalgorithm

A simple numerical algorithm for the design of a rectangular directional coupler (RDC) with arbitrary couplings is proposed. The performance of a designed RDC is also described. It is seen that the measured data agree well with the results predicted by using the proposed algorithm     

Broadband microstrip directional coupler

A nonuniform microstrip directional coupler with sinusoidally modulated coupling function is presented. The ripple and the amplitude response are controlled by the index of modulation m and the periodicity P of the function. For demonstration, a 20 dB ± 6% coupler is constructed on two different substrates and the experiment shows much flatter coupling response than the uniform or exponential line directional couplers.     

Novel acoustic-surface-wave directional coupler with diverse applications

An acoustic-surface-wave directional coupler is proposed that may be used on materials having a large electromechanical coupling constant to couple two acoustic beams which are many wavelengths wide. The normal modes of the coupler are identified and used with an equivalent-circuit representation of the device to predict the length of the structure needed for complete energy transfer. The theory indicates that the device can have an intrinsic bandwidth near to 100%.     

Three-Line microstrip directional coupler with dielectric overlay

The letter illustrates that the frequency characteristics of a three-line microstrip directional coupler can be greatly improved by using the dielectric overlay. We show the method of analysis in detail. The examples of design data are shown with the graphs of frequency characteristics of the coupler     

Switching power reduction using a pumped nonlinear directional coupler

We show that in a nonlinear directional coupler (NLDC) in which the signal is controlled by a pump of appropriate and different wavelength, the power needed for full switching is 3 times lower than for the same device used as a self switch. This power requirement is only /spl radic/3 times higher than for a Mach-Zehnder switch, which makes the NLDC even more appealing for practical multiplexing and switching applications.     

Low-voltage vertical directional coupler switch with suppressedelectroabsorption

We have studied the performance of a vertical directional coupler in which a multiple quantum well and a bulk semiconductor material act as the cores of the two guides in two arms. The power output of the device is expected to be unaffected by the electroabsorption effect in a directional coupler based on quantum confined Stark effect even when operated very close to the excitonic absorption edge. The above principle is utilized in realizing low-voltage switching and almost equal power in bar and cross states in a multiple-quantum-well (MQW) vertical directional coupler. Our calculation for a vertical coupler composed of InGaAsP bulk and InGaAsP-InP MQWs show switching voltages comparable to that of a similar coupler composed of a more complex barrier reservoir and quantum well electron transfer (BRAQWET) structure, with a slightly lower value of power output     

Polymer-based directional coupler modulator with high linearity

A generalized novel two-section directional coupler modulator with a linear transfer function is presented. This scheme introduces different coupling coefficients for each of the sections. We show that this configuration effectively suppresses the third-order intermodulation distortion compared to a conventional Mach-Zehnder modulator. It can be easily implemented by the photobleaching technique in polymer technology and demonstrates a simple and promising design for high-performance analog optical links without a complicated structure or electrical control.     

Grating-assisted directional coupler filters using AlGaAs/GaAs MQW waveguides

Wavelength demultiplexing in the 800 nm region is demonstrated using grating-assisted vertical codirectional coupler filters formed in two AlGaAs/GaAs multiple quantum well (MQW) ridge waveguides. A filter bandwidth as narrow as 3 nm (full width at half maximum) and interwaveguide coupling efficiency of 95% with a coupling length of only 430 mu m were achieved. Channel spacing of 4 nm was obtained for five-channel wavelength demultiplexing with crosstalk suppression in excess of 10 dB.<>     

Integrated bistable optical multivibrator using electrooptically controlled directional coupler switches

An integrated bistable optical multivibrator based on two electro-optical directional coupler switches has been realised for the first time using Ti: LiNbO3 waveguides with two crossed feedback loops. The analysis and operation of the basic optical flip-flop are presented, and different feedback conditions and loops should provide other types of optical multivibrators, e.g. monostable and astable.     

Optical waveguide directional coupler measurements using amicrocomputer-assisted TV camera system

Characterization of optical waveguide directional couplers using a microcomputer-assisted TV camera system is reported. A fluorescent technique is employed to visualize wave propagation in the optical waveguides, which exhibit small scattering. The method is simple and reproducible, and can be used to estimate waveguide losses and evaluate various optical devices such as waveguide lenses and waveguide interferometers on substrates. As an example of its application, parallel and nonparallel dual-chamber directional couplers and parallel triple-channel directional couplers are measured. Power transfer between the coupled channel waveguides is observed clearly, and coupling coefficients of the couplers are obtained nondestructively. The measured performance of the couplers is in good agreement with that predicted by coupled-mode analysis     

Semiconductor monolithic wavelength selective router using agrating switch integrated with a directional coupler

A semiconductor monolithic wavelength selective router is proposed. An electrically tunable grating switch is monolithically integrated with a directional coupler. The effect of sidelobe on the demultiplexing characteristics of the router is investigated, and it is shown that the sidelobes degrade the wavelength crosstalk and introduce a power penalty for demultiplexing characteristics. A phase-synchronized sampled grating is introduced to suppress the sidelobes, and wavelength router switching is observed in this structure. The extinction ratio is over 10 dB at a current injection of 25 mA. Using this structure, power-penalty-free wavelength selective routing at a 2.5 Gb/s wavelength-division-multiplexed NRZ random pattern is demonstrated     

All-optical multiplexing of femtosecond signals using an AlGaAsnonlinear directional coupler

The authors demonstrate multiplexing of femtosecond signals without the usual 3 dB loss of conventional passive multiplexers using an AlGaAs nonlinear directional coupler controlled by strong pump pulses     

A directional coupler acoustooptic filter with reduced sidelobelevels

A two-waveguide directional coupler filter with an acoustically induced grating structure is proposed. The directional coupler filter has the advantage that it does not require input and output polarizers and does not require specific birefringent material properties. Since multiple acoustic waves could be applied simultaneously, this property could be used to couple both TE and TM polarizations from one waveguide to the other. This allows for filtering the required optical wavelength from both polarizations simultaneously. A notable weakness of acoustooptical filters and all mode-coupling filters is the high sidelobe levels in their optical transmission spectrum. A technique to suppress these high sidelobe levels in the proposed acoustooptic filter is presented. It is based on simultaneous application of several acoustic waves on the optical waveguide. This technique could be applied to any existing configuration of acoustooptic filters     

定向耦合器自动方向性调节的设计

为了减少对调试员工的依赖性,提高产品调试速度和检测精度,设计出一种可以实现自动方向性调节的定向耦合器.与传统方法相比,该方法采用PIN型二极管代替调节电容,利用其阻抗可变特性,通过偏置电压来调节匹配阻抗,最终实现定向耦合器的自动方向性调节.通过实验验证和最终批量测试数据表明该方法摆脱了传统调节方式对人工的依赖,通过较少的元件实现了自动调节,可以提高检测精度和产品的一致性,产品的调节时间减少了约80%.     

定向耦合器自动方向性调节的设计

为了减少对调试员工的依赖性,提高产品调试速度和检测精度,设计出一种可以实现自动方向性调节的定向耦合器。与传统方法相比,该方法采用PIN型二极管代替调节电容,利用其阻抗可变特性,通过偏置电压来调节匹配阻抗。最终实现定向耦舍器的自动方向性调节。通过实验验证和最终批量测试数据表明该方法摆脱了传统调节方式对人工的依赖。通过较少的元件实现了自动调节,可以提高检测精度和产品的一致性,产品的调节时间减少了约80％。     

基于缺陷地结构的三分支线定向耦合器设计

针对高特征阻抗微带传输线的线宽过窄难以加工实现以及器件耐功率性差的问题,提出了利用缺陷地结构(DGS)提高微带传输线特征阻抗的方法,在传统三分支线定向耦合器结构支节线下方接地平面设计蚀刻矩形DGS结构,实现高特征阻抗支节线,完成阻抗匹配,且实现了较大的工作带宽。采用电磁仿真软件进行建模仿真分析、参数优化并制作出实际电路进行测试验证,结果表明该定向耦合器在4.5~5.5 GHz频带内具有较低的插入损耗、较高的幅度和相位稳定度,性能良好,具有一定的实用价值。