共查询到19条相似文献,搜索用时 140 毫秒
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单负材料所具有的电磁禁带特性可应用于阵列天线中降低天线单元间的互耦.文中研究设计了一种电单负材料结构单元ENG-APSL, 采用等效电路和波导传输法分析了ENG-APSL的电磁特性, 并提取等效参数.然后, 将基于ENG-APSL单元构成的隔离器用于抑制微带阵列单元间的互耦.研究表明, 天线阵列单元间距为0.37λ0(λ0为天线工作频率波长)条件下, 加载隔离器后天线阵列单元的E面耦合度降低了21 dB, 并且在工作频率(5.1 GHz)附近隔离度大于25 dB的带宽达到5.1%.同时, 该隔离器具有结构简单、尺寸小的突出优势. 相似文献
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为获得一种开关效应强、响应快且结构简单的光开关,对一种基于二色性染料及聚合物取向的液晶光开关进行研究。通过在垂直配向的液晶中加入二色性染料及聚合物,并在施加偏压的情况下照射紫外光使其发生聚合物取向效应,制得了一种具有电控偏光特性的液晶盒,进而将这种液晶盒按照偏光角度为0°/90°的方式组合为液晶光开关。对所制得液晶光开关的插入损耗、消光比和响应特性进行测试,结果表明,所制得的液晶光开关的插入损耗小于0.6dB、消光比超过13dB,具有较明显的开关效应,聚合物取向的方法则可以消除这种液晶光开关的迟滞现象,使其开关时间降低到20ms以内;通过聚合物取向过程所施加偏压的控制,二选一地,可以进一步减少其插入损耗或开关时间。 相似文献
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Walk—off型单级偏无关光隔离器 总被引:1,自引:0,他引:1
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。 相似文献
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非互易波导光栅的滤波特性与应用 总被引:1,自引:0,他引:1
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. 相似文献
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磁光隔离器是光通信系统中的关键器件.为确保光通信系统宇航应用可靠性,对磁光隔离器的宇航应用评估进行了研究.在介绍磁光隔离器的工作原理、内部关键元件法拉第旋转片、装配工艺和典型光学参数的基础上,重点从磁光隔离器宇航应用评估基础验证设计方面展开磁光隔离器宇航应用评估研究.由此,进行了验证指标体系的设计、失效模式的分析、验证... 相似文献
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A compact optical isolator has been designed, with monomode optical fibre pigtails, for use at a wavelength of 1.3 ?m. The device has an isolation of greater than 26 dB and a fibre-to-fibre insertion loss of 3.5 dB, and the return loss is better than 26 dB. 相似文献
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钒酸钇晶体楔型光隔离器 总被引:5,自引:1,他引:4
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. 相似文献
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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.<> 相似文献
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A novel radiative optical isolator and a circulator are discussed in this paper. It is numerically estimated that with λ=1.3 μm, 45-dB isolation ran be achieved with an isolator of 8 mm in length. For a 21.5-mm-long 4-port circulator, the achievable isolation is about 45 dB, with approximately 1-dB insertion loss 相似文献
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An optical isolator for use at 1.32 ?m has been fabricated using standard communication-grade single-mode fibre as an optical rotator fitted with high-birefringence fibre pigtails containing an in-line tapered fibre polariser. A novel adjustment procedure ensures isolation levels are limited only by the polariser extinction ratio. Isolation levels in excess of 21 dB have been recorded with an insertion loss of less than 3 dB. 相似文献
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A uniquely designed, mechanically tunable, bulk optical isolator for the 1.2 to 1.7 ?m wavelength range is described. The isolator can be tuned for isolation better than 32 dB over the operating wavelength range with a forward loss ranging from -3.6 dB at 1.2 ?m to -0.8 dB at 1.6 ?m. 相似文献
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It has been recognized for some time that reflections back into the cavity of an injection laser from a mechanically unstable external mirror cause noise in the output of the laser (reflection noise). In this paper, noise measurements are presented for index-guided lasers as functions of the output power, the degree of optical isolation and external cavity length (5-15 cm), while current modulation (using 2-4 mA at 50-200 MHz) has been used to reduce the noise levels by as much as 20 dB. It is demonstrated that the mechanism of noise reduction by modulation is the frequency modulation of the laser's spectrum and its interaction with the modes of the external cavity. It is shown that using an optical isolator can give a relative intensity noise of -110 dB while using modulation in addition can reduce this to -125 dB; the bandwidth performance of optical storage systems is discussed in terms of these two schemes. 相似文献