Faraday Optical Isolator/Gyrator Design in Planar Dielectric Waveguide Form

The possibilities of using the magnetic Faraday effect to provide a planar dielectric waveguide isolator or circulator are studied. At least two active elements which couple the TE and TM waveguide modes are required. One of these is magnetooptic. Preliminary design data for a dielectric waveguide isolator in which the mode-converting media forms the substrate and top layer of a single waveguide structure are reported. This design should prove more practical than the optical tandem structures proposed previously.     

钒酸钇晶体楔型光隔离器

介绍了用钒酸钇晶体的与偏振无关的Ｗｅｄｇｅ型光隔离器的基本原理，用琼斯矢量法得到了插入损耗和隔离度的数学表达式，并介绍了隔离器的结构设计．制作的隔离器光纤到光纤的插入损耗为１．０４ｄＢ，隔离度为４２ｄＢ，回程损耗为４４．３ｄＢ，偏振灵敏度≤０．２ｄＢ，带宽大于４０ｎｍ，体积为１０×１０×４０ｍｍ３．     

Development of a three-axis active vibration isolator using zero-power control

This paper presents the development of an active 3-degree-of-freedom (DoF) vibration isolation system using zero-power magnetic suspension. The developed system is capable to suppress direct disturbances and isolate ground vibrations of the 3-DoF motions, associated with vertical translational and rotational modes. Two categories of control strategy for the actuators are proposed, i.e., local control and mode control. The latter method allows to overcome limitations of the poor performances for rotational modes exhibited by the former. A mathematical model of the system is derived and each DoF motion is treated separately for the control system. It is demonstrated analytically that the infinite stiffness to static direct disturbances can be generated and the resonance peak due to floor vibration can effectively be suppressed for the system. Moreover, the experiments have been carried out to measure the static and dynamic responses of the isolation table to direct disturbances, and transmissibility characteristic of the isolator from the floor. The results indicate good vibration isolation and attenuation performances, and show the efficacy of the developed isolator for industrialization.     

FPGA-based fully digital controller for three-phase shunt active filters

This article presents a fully digital controller for a three-phase shunt active filter. The harmonic isolator and the current controller both have been implemented in only one Field Programmable Gate Array (FPGA). This article discusses the design and implementation of digital hybrid modulated hysteresis current controller and multi-variable filters for shunt active filter controlling. Simulation and experimental results based on ‘FPGA in the loop’ prototyping demonstrate the effectiveness of the proposed fully digital controller.     

New configuration of polarisation-independent isolator using a polarisation-dependent one

In optical communication systems using fibre amplifiers, polarisation-independent isolators with high isolation are desirable. A simple effective method to realise polarisation-independent optical isolators is proposed. The isolator consists of spatial walk-off polarisers, half-wave plates, and a conventional polarisation-dependent isolator. The measured forward loss of the assembled isolator is 0.38 dB and 0.32 dB at 1.3 and 1.55 mu m wavelengths, respectively. The backward loss is 55.5 dB and 63.5 dB at 1.3 and 1.55 mu m wavelengths, respectively.<>     

Novel multioctave MMIC active isolator (1-20 GHz)

Presents a multioctave MMIC active isolator (1-20 GHz) requiring only two field-effect transistors (MESFETs or HEMTs) and exhibiting more than 20 dB input return loss, 18 dB output return loss with more than 20 dB reverse loss and less than 9 dB transmission loss.<>     

液晶在光隔离技术中的应用研究

利用手性液晶的Bragg选择反射特性,理论分析了液晶在光隔离技术中的应用可能性.实验结果证实,液晶光隔离器对单色光具有较好的光隔离特性(光隔离度＝13dB)和较高的正向透过率(插入损耗＝1dB),在大口径光隔离器的制造上具有重要的应用价值.     

100 W average power 10.6 µm isolator based on the interband Faraday effect in InSb

A 10.6 μm isolator based on the interband magnetic optical effect in InSb has been tested to throughput levels of 100 W average power. The interband isolator figure of merit (rotation/loss) has been shown to be nearly a factor of two greater than the optimum free carrier effect isolator. Employment of the isolator at a 10.6 μm laser radar field site has resulted in the improvement of frequency stability and Doppler resolution.     

A New Fin-Line Ferrite Isolator For Integrated Millimeter-wave Circuits

A ferrite isolator in fin-line technique is investigated both theoretically and experimentally. Since fin-line field distributions exhibit similar properties, the realilzation of a field displacement isolator is possible applying the principles of operation known from metal waveguide isolators. A field expansion method for a simplified isolator model is presented for the investigation of the field theoretical problem. Furthermore the feasibility of the fin-line field displacement approach for the realization of an isolator is demonstrated experimentally at the model frequency of 11 GHz.     

Reflection insensitive erbium-doped fiber amplifier

It is experimentally and theoretically examined how the insertion of an isolator within the erbium-doped fiber influences the sensitivity of the fiber amplifier to external reflections. We examined the EDFA in various regions of saturation, and compared the configuration with the isolator to the traditional configuration without an isolator. The most significant improvements were found in the small-signal region, where the requirements to reflections may be relaxed by as much as 13 dB. This, together with an improved gain and noise figure, makes the configuration with the isolator very attractive for preamplifier applications     

两段级联宽带碲基掺铒光纤放大器特性研究

利用四能级结构速率方程组和光功率传输方程组,研究了在碲基掺铒光纤(EDTF)中内插一个光隔离器、形成两段级联的碲基掺铒光纤放大器(EDTFA)后对EDTFA性能的改善.结果表明,在给定泵浦方式、泵浦功率、纤芯掺杂浓度和输入信号功率条件下,两段级联EDTFA可以有效的抑制光纤中反向传输放大自发辐射(ASE)噪声,降低反转粒子数的消耗,从而提高信号增益、输出功率,并且降低了噪声系数.对不同光纤长度和光隔离器内插在光纤中不同位置的研究表明,当光纤为最佳长度和光隔离器在最佳位置处时,可使短波长信号增益增加10 dB,噪声系数减小1 dB,并进一步增加了放大带宽以及功率转换效率.     

Fiber-embedded in-line isolator

A fiber-embedded optical isolator with a low forward loss has been developed. The isolator consists of thermally diffused expanded core fibers, laminated polarizers, and a Faraday rotation garnet. Backward and forward losses at 1.3 μm wavelength are 44.0 and 0.9 dB, respectively. The isolator has a minute size, and its alignment is simple     

光纤传输用的磁光隔离器

本文报导了光纤通信用光隔离器的研究工作.隔离器由稀土铁石榴石法拉第旋转器及两只方解石棱镜组成.在波长为1.15微米时,器件插入损耗为2.4分贝,隔离比为34.8分贝.讨论了使用不同的复合稀土铁石榴石材料及采用不依赖偏振光技术对器件性能的改进.     

Room temperature solid-state plasma nonreciprocal microwave devices

Nonreciprocal microwave propagation at room temperature in a waveguide which contains of a thin slab n-InSb has been demonstrated by the construction of an isolator, a three-port circulator, and a variable power divider, all operating at K-band frequencies. A forward loss and an isolation of 3 and 15 dB, respectively, was observed for the isolator; the forward and backward losses between adjacent ports of the circulator were 3 and 20 dB, respectively, and the power ratio of the divider could be varied from 1 to 10 for a given direction of the magnetic field. Transmission losses of about 3 dB were present in the forward direction and in each case, all but 1 dB of these were shown to be due to reflections resulting from impedance mismatch.     

几种新型结构光纤隔离器

简要介绍了光纤隔离器的原理及其在光通信中的应用。着重分析讨论了几种新型光纤光隔离器的原理,结构及性 能。总结了光纤隔离器的发展现状,探讨了光纤隔离器的发展前景及方向。     

A V-Band Communication Transmitter and Receiver System Using Dielectric Waveguide Integrated Circuits

A V-band communication transmitter and receiver is described. Both units make extensive use of passive microwave components fabricated rising millimeter-wave insular line integrated circuits (MILIC's). These components consist of rectangular dielectric rod antennas, a MILIC ferrite isolator, a bandpass ring filter, a directional coupler, and sections of dielectric insular waveguide. The passive insular waveguide components are integrated together, along with split block metal waveguide mounts for the active devices, in order to form the RF circuitry of the transmitter and receiver.     

两段型高性能光隔离器的设计与分析

提出了一种新的两段型高性能与偏振无关光隔离器的结构，给出了其设计思想和工作原理。对法拉第旋光器用的圆筒形磁铁进行了理论分析和计算，所得的结果对法拉第旋光器用的磁铁设计有具体的指导作用。通过借助矩阵光学理论，对光隔离器进行了数学分析，为与偏振无关光隔离器的性能分析和讨论作了有益的尝试。     

测量光隔离器隔离度的新方法

提出一种测量光隔离器的隔离度的方法，可消除隔离器反射光的影响，并以λ／４片光隔离器进行了测量，取得较好的效果。     

高性能表面安装型激光隔离器的研制

基于高斯光束耦合理论,对光斜面耦合的光隔离器回波损耗进行了分析,通过改进核心元件的加工组合工序,采用表面安装技术,研制了光斜面耦合的高性能表面安装型光隔离器,测试结果表明,这种表面安装光隔离器具有优异的性能参数.     

Design of a New Broad-Band Isolator

The design theory and experimental results of a proposed broad-band technique of an isolator are presented. The isolator not only has a broad-band backward loss but also a low broad-band insertion loss. The network constants and the performance are obtained in connection with the magnetic loss of ferrite, and they are confirmed by experimental data. The trial ultrawide-band isolator the performance of 20-dB isolation over the frequency band from 70 MHz to 800 MHz.