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。     

法拉第磁光隔离器

法拉第磁光隔离器可有效地消除光学反馈,在稳频激光、激光通讯和激光信息处理等系统中得到广泛应用。本文介绍了其工作原理、典型结构和各类法拉第材料的特性,说明了可调谐隔离器和宽带隔离器的结构和原理,并报告了国际市场上商品磁光隔离器的简况。     

非互易波导光栅的滤波特性与应用

根据磁光材料的非互易特性和波导光栅的滤波特性,介绍了一种磁光波导光栅的非互易滤波特性及其应用.该磁光波导光栅采用法拉第旋转系数为4800°/cm的掺铈钇铁石榴石(Ce:YIG)材料、单模的脊型补偿墙截面结构和cosine型变迹光栅结构的设计.利用有限差分法和等效折射率法模拟该磁光波导光栅非互易效应的大小,同时结合耦合模理论和转移矩阵法对该磁光波导光栅的非互易滤波特性进行分析.结果表明,对于TE模和1550 nm波段,该磁光波导光栅正反向传输的中心波长偏移0.8 nm,带宽0.4 nm(-20 dB).这种非互易滤波特性可以用来实现波长选择光隔离器和光分插复用器(OADM)等集成光学器件.     

光通信系统用光隔离器研究

详细介绍了在线式偏振无关光隔离器和微型化偏振相关光隔离器的工作原理，以及两种隔离器系列的各项性能指标。其主要性能指标达到国内先进水平，并达到了９０年代国外同类光隔离器的水平。     

氟硅凝胶对陶瓷封装隔离器漏电流的影响

陶瓷封装隔离器具有高可靠性，灌胶可加强其绝缘性能，但还需要考虑灌胶对隔离器漏电流的影响。以GL3200C型陶瓷封装隔离器为研究对象，研究了氟硅凝胶通过内部水汽对陶瓷封装隔离器漏电流的影响，对隔离器在不同温度下进行稳定性烘焙10 h后测量其内部水汽含量，并分析内部水汽含量对隔离器漏电流的影响。结果表明，在不超过150℃的条件下，氟硅凝胶会分解产生烃类物质并释放至GL3200C封装内，但并不释放水汽，灌胶不会影响陶瓷封装隔离器的漏电流指标，满足隔离器的可靠性要求，但是存在稳定性不足和引入腐蚀性离子的风险。研究结果为工程应用上灌胶的选择提供了参考。     

寻呼发射同轴隔离器（单向器）

寻呼发射同轴隔离器（单向器）邮电部第一研究所研制的ＰＴＧ—３０５型寻呼发射同轴隔离器具有单向性，可有效地抑制无线寻呼发射台之间的互调于扰，提高通信质量，并可避免由天线变化所引起的反射功率对发射机的不良影响，从而进一步提高发射机工作稳定性。该同轴隔离器...     

旋光性与各向异性材料衬底薄膜光波导中波的传播

本文分析磁性、光激励或双折射材料衬底上的光波导中波的传播;推导TE-TM模的转换条件;获得了用计算机表示石英衬底模式转换器特性的计算结果;对采用两只串联模式转换器的旋光器作出了数学分析;并论述隔离器、调制器、光开关和光学读出器等的设计方案。     

微型单级偏振无关光隔离器的设计与实验

研制了一种新型的微型单级偏振无关光隔离器,给出了光隔离器中自聚焦透镜、双折射晶体平行平板和法拉第旋转片的设计,介绍了光隔离器的制作方法,并对其性能进行了测试。实验结果表明:插入损耗为0.5 dB,0λ±20 nm带宽范围内最小隔离度为30 dB,最大隔离度为45 dB,偏振相关损耗小于0.1 dB,偏振模色散小于0.05 ps。     

一种微型宽带光隔离器的设计研制

文章提出了一种小型化光隔离器的设计方案,通过理论分析其实现原理以及各个光学参数,并由实验证实了该方案的有效性。设计结果表明,在保证获得优良参数情况下,采用该方案能使光隔离器结构更紧凑,且有效降低其成本和装配难度。通过1／4波片及全波片对法拉第旋光片的旋光色散特性补偿后,可使该器件的隔离度参数随波长变化不敏感,此外,由于采用对称的光路设计,该方案的偏振模色散理论值为0,无需额外补偿。     

利用非线性偏振旋转锁模技术产生0.7nJ,1.5ps光脉冲

为了研究锁模光纤激光器以增益平坦型掺铒光纤放大器作为增益介质对输出特性的影响,采用增益平坦型掺铒光纤放大器结合光纤偏振控制器、偏振相关光隔离器组成锁模光纤激光器,基于非线性偏振旋转锁模技术,实现稳定、自起振锁模运转,得到了中心波长1560nm、重复频率6.495MHz、单脉冲能量0.7nJ、脉宽1.5ps的超短光脉冲。同时实验观察到峰值波长为1557nm和1570nm的双峰值波长锁模脉冲的产生。结果表明,采用增益平坦型掺铒光纤放大器替代普通掺铒光纤组成锁模光纤激光器,可获得较高单脉冲能量的超短光脉冲,锁模脉冲的输出光谱可能出现双峰结构,从而可为超短脉冲光纤激光器设计及实用化提供参考。     

A New Type of Isolator Using the Edge-Guided Mode (Letters)

Experirnents on a new edge-guided mode isolator are reported. In this isolator, one edge of a wide strip is shorted to the ground, and no lossy electrical materials are used. Large isolation and small insertion losses were obtained.     

Waveguide Isolator With Phase Mismatch

A novel optical waveguide isolator constructed from mode convertors with unsuppressed phase mismatch is proposed. The troublesome requirement of phase matching for transverse electric (TE)-transverse magnetic (TM) mode conversion is eliminated without degradation on the performances. It is found that a kind of self-phase compensation phenomenon occurs during TE-TM mode conversion that facilitates the operation of the isolator. An isolator based on this mechanism is designed and simulated. An isolation of -24.4 dB is obtained.     

A 35-GHz Isolator Using a Coaxial Solid-State Plasma in a Longitudinal Magnetic Field

The device considered in this study is a semiconductor isolator consisting of a circular waveguide with a cylindrical rod of n-type InSb mounted coaxially in the guide. To achieve nonreciprocal operation, the InSb was cooled to liquid nitrogen temperature, a dc magnetic field was applied parallel to the direction of propagation, and a circularly polarized signal was used to excite the waveguide containing the rod. The pertinent solution of Maxwell's equations was programmed for a digital computer to allow numerical evaluation of the characteristics of the isolator using an InSb rod in which losses were present. Experimental data for various parameters and the corresponding calculated data are presented and compared. Low forward loss is achieved with the present coaxial geometry because of strong power concentration effects within or outside of the InSb rod as a function of the direction of propagation. Two series of calculated mode patterns are presented that demonstrate two types of operation of the isolator in achieving a high loss for one direction of propagation, one depending on field displacement, the other on mode coupling. These data are again compared to the experimental evidence.     

Theoretical Analysis of the Operation of the Field-Displacement Ferrite Isolator

A theoretical analysis of the resistance-sheet isolator is carried out, and numerical solutions are obtained for the forward and reverse propagation constants of the distorted dominant mode in a rectangular waveguide containing a transversely magnetized thick ferrite slab displaced slightly from the side wall. The microwave electric field patterns within the waveguide are plotted for several values of the physical design parameters of the isolator for which experimental performance data have been reported. Field patterns are used to describe the principles of the isolator and to select the optimum values of slab thickness, internal dc magnetic field, ferrite magnetization, and location of the slab in the waveguide for the idealized isolator. Evidence is presented to show that it is necessary to use a comparatively thick ferrite slab located in a very small usable range of distances from the side wall. The appropriate value of internal dc magnetic field is simply related to the magnetization of the ferrite and to the frequency. It has not been necessary to take into account the perturbing effects of the resistance card or matching techniques in order to explain the basic design principles.     

New Edge-Guided Mode Isolator Using Ferromagnetic Resonance Absorption

A new edge-guided (EG) mode isolator is described in which nonreciprocal attenuation is due to the ferromagnetic resonance absorption caused by a strong dc magnetic field applied locally at the short-circuited edge of a ferrite microstrip line. From modal analysis, including the magnetic losses of ferrite substrate and the transversal variation of the internal dc magnetic field, the dominant EG mode has been proved to propagate along not only the conventional ferrite stripline but also a stripline with one edge short circuited to the ground. Dispersion relations and RF electric field distribution have been calculated numerically, and the upper limit of isolator bandwidth has been discussed with several design parameters. Based on the results, a practical EG mode resonance isolator has been successfully developed, which has more than 25 dB isolation loss and less than 1.0 dB insertion loss over a 4.0-8.0-GHZ frequency band throughout the - 10/spl deg/C-+60/spl deg/C temperature range,     

Walk—off型单级偏无关光隔离器

介绍了新型的偏振无关光隔离器,给出了walk-off型单级偏振无关光隔离器的设计及原理分析,并对其性能进行了测试。结果表明：最大隔离度达到了45.17dB,隔离度大于35dB的带宽达到了38nm,插入损耗为1.2dB。     

Theory and Applications of Coupled Optical Waveguides Involving Anisotropic or Gyrotropic Materials

Coupled optical waveguides consisting of two isotropic dielectric slab waveguides coupled through anisotropic or gyrotropic materials inserted between them, are treated theoretically in detail. The properties of reciprocal and nonreciprocal TE-TM mode conversion and a nonreciprocal phase shift for TM modes are shown. As an example of application of this type of coupled waveguide, a nonreciprocal optical integrated circuit (IC) mode converter is proposed. It is shown that a circulator and an isolator which require neither mode separators nor mode filters can be constructed by utilizing the proposed nonreciprocal mode converter. The numerical design examples are also given.     

A New Edge-Mode Isolator in the Very High Frequency Range

An edge-mode isolator, using a magnetostatic surface mode operates in the very high frequency (VHF) range below the gyromagnetic resonance.     

Spectral-domain immittance approach for the propagation constantsof unilateral finlines with magnetized ferrite substrate

The admittances of TM and TE modes in a ferrite substrate are given, and the propagation constants for the forward and backward directions of the dominant mode in unilateral finlines with magnetized ferrite substrates are obtained. The solution is obtained by applying the transverse equivalent transmission line in the spectral domain and Galerkin's method. Numerical results are presented which can be used in designing a finline displacement isolator     

A distributed millimeter-wave isolator using nonreciprocal coupling structure

A new distributed millimeter-wave isolator is proposed. This device employs a nonreciprocal coupling mechanism between a dielectric slab and a conductor-backed ferrite slab. Transverse resonance and mode matching techniques are used for analysis. A numerically optimized structure at 200 GHz will be discussed and experimental results at 35 GHz will be presented.